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Lewis KH, Gudzune KA, Ard JD. Phentermine in the Modern Era of Obesity Pharmacotherapy: Does It Still Have a Role in Treatment? Curr Obes Rep 2024; 13:132-140. [PMID: 38172485 DOI: 10.1007/s13679-023-00546-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 12/02/2023] [Indexed: 01/05/2024]
Abstract
PURPOSE OF REVIEW This review provides an overview of the history, mechanism of action, and expected treatment effects of the anti-obesity medication (AOM), phentermine. It also includes a summary of recent research and practical guidance for prescribing clinicians. RECENT FINDINGS Recent research on phentermine is sparse and consists primarily of observational studies with methodologic limitations. These studies suggest that phentermine use is associated with clinically significant weight loss in adults and that the medication is generally well tolerated. Large-scale observational studies evaluating phentermine's safety have not identified an increased risk of cardiovascular events or elevations in blood pressure. There is no data to support the notion that phentermine is addictive. Although it remains the most commonly prescribed AOM in the USA, phentermine has little rigorous research to support its efficacy and safety in long-term treatment, which creates a dilemma with guideline-recommended chronic use of AOMs. While we await forthcoming conclusive data on this front, clinicians may consider using phentermine long-term in selected patients, if such prescribing is consistent with local regulatory statutes.
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Affiliation(s)
- Kristina H Lewis
- Department of Epidemiology & Prevention, Division of Public Health Sciences, Wake Forest University School of Medicine, Medical Center Blvd., Winston-Salem, NC, 27101, USA.
| | - Kimberly A Gudzune
- Department of Medicine, Division of General Internal Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Health Policy & Management, Johns Hopkins University School of Public Health, Baltimore, MD, USA
| | - Jamy D Ard
- Department of Epidemiology & Prevention, Division of Public Health Sciences, Wake Forest University School of Medicine, Medical Center Blvd., Winston-Salem, NC, 27101, USA
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Limón-Bernal E, Roa-Coria JE, Zúñiga-Romero Á, Huerta-Cruz JC, Ruíz-Velasco IRC, Flores-Murrieta FJ, Lara-Padilla E, Reyes-García JG, Rocha-González HI. Anorectic interaction and safety of 5-hydroxytryptophan/carbidopa plus phentermine or diethylpropion in rat. Behav Pharmacol 2021; 32:368-381. [PMID: 33660661 DOI: 10.1097/fbp.0000000000000625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Drug combinations are being studied as potential therapies to increase the efficacy or improve the safety profile of weight loss medications. This study was designed to determine the anorectic interaction and safety profile of 5-hydroxytryptophan (5-HTP)/carbidopa + diethylpropion and 5-HTP/carbidopa + phentermine combinations in rats. The anorectic effect of individual drugs or in combination was evaluated by the sweetened milk test. Isobologram and interaction index were employed to determine the anorectic interaction between 5-HTP/carbidopa and diethylpropion or phentermine. Plasma serotonin (5-HT) was measured by ELISA. Safety of repeated doses of both combinations in rats was evaluated using the tail sphygmomanometer, cardiac ultrasound, hematic biometry and blood chemistry. A single oral 5-HTP, diethylpropion or phentermine dose increased the anorectic effect, in a dose-dependent fashion, in 12 h-fasted rats. A dose of carbidopa at 30 mg/kg reduced the 5-HTP-induced plasmatic serotonin concentration and augmented the 5-HTP-induced anorectic effect. Isobologram and interaction index indicated a potentiation interaction between 5-HTP/30 mg/kg carbidopa + diethylpropion and 5-HTP/30 mg/kg carbidopa + phentermine. Chronic administration of experimental ED40 of 5-HTP/30 mg/kg carbidopa + phentermine, but not 5-HTP/30 mg/kg carbidopa + diethylpropion, increased the mitral valve leaflets area. Moreover, there were no other significant changes in cardiovascular, hematic or blood parameters. Both combinations induced around 20% body weight loss after 3 months of oral administration. Results suggest that 5-HTP/30 mg/kg carbidopa potentiates the anorectic effect of diethylpropion and phentermine with an acceptable safety profile, but further clinical studies are necessary to establish their therapeutic potential in the obesity treatment.
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Affiliation(s)
- Ernesto Limón-Bernal
- Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional
| | - José E Roa-Coria
- Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional
| | - Ángel Zúñiga-Romero
- Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional
| | - Juan C Huerta-Cruz
- Unidad de Investigación en Farmacología, Instituto Nacional de Enfermedades Respiratorias, Ismael Cosio Villegas
| | - Irma R C Ruíz-Velasco
- Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, Ciudad Universitaria, Coyoacán, Ciudad de México, Mexico
| | - Francisco J Flores-Murrieta
- Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional
- Unidad de Investigación en Farmacología, Instituto Nacional de Enfermedades Respiratorias, Ismael Cosio Villegas
| | - Eleazar Lara-Padilla
- Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional
| | - Juan G Reyes-García
- Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional
| | - Héctor I Rocha-González
- Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional
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Istfan NW, Anderson WA, Hess DT, Yu L, Carmine B, Apovian CM. The Mitigating Effect of Phentermine and Topiramate on Weight Regain After Roux-en-Y Gastric Bypass Surgery. Obesity (Silver Spring) 2020; 28:1023-1030. [PMID: 32441476 PMCID: PMC7250052 DOI: 10.1002/oby.22786] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 01/23/2020] [Accepted: 02/10/2020] [Indexed: 12/18/2022]
Abstract
OBJECTIVE Weight regain (WR) after Roux-en-Y gastric bypass surgery (RYGB) starts to occur 2 years after surgery, ultimately affecting at least 25% of patients. A limited number of studies have evaluated the impact of antiobesity medications (AOMs) on this phenomenon. METHODS This study reviewed the electronic medical records of 1,196 patients who underwent RYGB between 2004 and 2015. WR was evaluated by comparing each patient's weight during subsequent postoperative office visits to nadir weight (lowest weight after RYGB, n = 760), taking into consideration the interval during which WR occurred. Patients who were prescribed AOMs and came to follow-up visits were classified as adherent users, whereas those who missed their follow-up visits were considered nonadherent. This study used a linear mixed model, Cox regression, and generalized equation estimator to determine the impact of AOMs on WR trajectory, hazard ratio for time to event, and odds ratio for repeated event occurrence, respectively. RESULTS Despite the lack of a unified protocol for using AOMs, the three statistical models converged to show that phentermine and topiramate, used individually or in combination, can significantly reduce WR after RYGB. CONCLUSIONS Phentermine and topiramate are effective in mitigating WR after RYGB. Further studies are needed to help ascertain optimal use of AOMs after bariatric surgery.
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Affiliation(s)
- Nawfal W. Istfan
- Section of Endocrinology, Diabetes, Nutrition, and Weight Management, Department of Medicine, Boston University School of Medicine and Boston Medical Center, Boston, Massachusetts, USA
| | - Wendy A. Anderson
- Section of Minimally Invasive Surgery, Department of Surgery, Boston University School of Medicine and Boston Medical Center, Boston, Massachusetts, USA
| | - Donald T. Hess
- Section of Minimally Invasive Surgery, Department of Surgery, Boston University School of Medicine and Boston Medical Center, Boston, Massachusetts, USA
| | - Liqun Yu
- Section of Endocrinology, Diabetes, Nutrition, and Weight Management, Department of Medicine, Boston University School of Medicine and Boston Medical Center, Boston, Massachusetts, USA
| | - Brian Carmine
- Section of Minimally Invasive Surgery, Department of Surgery, Boston University School of Medicine and Boston Medical Center, Boston, Massachusetts, USA
| | - Caroline M. Apovian
- Section of Endocrinology, Diabetes, Nutrition, and Weight Management, Department of Medicine, Boston University School of Medicine and Boston Medical Center, Boston, Massachusetts, USA
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Safer DL, Adler S, Dalai SS, Bentley JP, Toyama H, Pajarito S, Najarian T. A randomized, placebo-controlled crossover trial of phentermine-topiramate ER in patients with binge-eating disorder and bulimia nervosa. Int J Eat Disord 2020; 53:266-277. [PMID: 31721257 DOI: 10.1002/eat.23192] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2019] [Revised: 09/28/2019] [Accepted: 10/14/2019] [Indexed: 02/05/2023]
Abstract
OBJECTIVE Open trials suggest phentermine/topiramate ER (PHEN/TPM-ER), food and drug administration (FDA) approved for obesity, has utility for binge eating. With no randomized controlled trials (RCTs) yet performed, this trial aimed to evaluate PHEN/TPM-ERs efficacy and safety in a crossover RCT for patients with binge-eating disorder (BED) or bulimia nervosa (BN). METHOD Participants were randomized to 12-weeks PHEN/TPM-ER (3.75 mg/23 mg-15 mg/92 mg) or placebo followed by 2-weeks drug washout, then 12-week crossover. Demographics, vitals, eating disorder behaviors, mood, and side effects were measured. Primary outcome was objective binge-eating (OBE) days/4-weeks; secondary outcomes included binge abstinence. Mixed-effect models estimated treatment effects, with fixed effects adjusting for treatment, study period, and diagnosis. RESULTS The 22 adults (BED = 18, BN = 4) were female (96%), Caucasian (55%), aged 42.9 (SD = 10.1) years with body mass index = 31.1 (SD = 6.2) kg/m2 . Baseline OBE days/4-weeks decreased from 16.2 (SD = 7.8) to 4.2 (SD = 8.4) after PHEN/TPM-ER versus 13.2 (SD = 9.1) after placebo (p < .0001), with abstinence rates = 63.6% on PHEN/TPM-ER versus 9.1% on placebo (p < .0001). Weight changes = -5.8 kg on PHEN/ TPM-ER versus +0.4 kg on placebo. Drop-out = 2 (9%) on PHEN/TPM-ER and 2 (9%) on placebo, with few side effects. Vital sign changes with PHEN/TPM-ER were minimal and similar to placebo. Responses were not significantly different for BED versus BN. DISCUSSION This first RCT to evaluate the efficacy and safety of PHEN/TPM-ER for BED/BN found this drug combination significantly more effective at reducing binge eating than placebo and well tolerated. However, with only four participants with BN, findings regarding the safety of PHEN/TPM-ER in patients with BN must be taken with caution. TRIAL REGISTRATION Clinicaltrials.gov identifier NCT02553824 registered on 9/17/2015. https://clinicaltrials.gov/ct2/show/NCT02553824.
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Affiliation(s)
- Debra L Safer
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, California
| | - Sarah Adler
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, California
| | - Shebani Sethi Dalai
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, California
| | - Jason P Bentley
- Quantitative Sciences Unit, Stanford University School of Medicine, Stanford, California
| | - Hannah Toyama
- Department of Psychology, Palo Alto University, Palo Alto, California
| | - Sarah Pajarito
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, California
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Simonds SE, Pryor JT, Koegler FH, Buch-Rasmussen AS, Kelly LE, Grove KL, Cowley MA. Determining the Effects of Combined Liraglutide and Phentermine on Metabolic Parameters, Blood Pressure, and Heart Rate in Lean and Obese Male Mice. Diabetes 2019; 68:683-695. [PMID: 30674622 DOI: 10.2337/db18-1149] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Accepted: 01/17/2019] [Indexed: 01/08/2023]
Abstract
Liraglutide, a glucagon-like peptide 1 (GLP-1) receptor agonist, and phentermine, a psychostimulant structurally related to amphetamine, are drugs approved for the treatment of obesity and hyperphagia. There is significant interest in combination use of liraglutide and phentermine for weight loss; however, both drugs have been reported to induce systemic hemodynamic changes, and as such the therapeutic window for this drug combination needs to be determined. To understand their impact on metabolic and cardiovascular physiology, we tested the effects of these drugs alone and in combination for 21 days in lean and obese male mice. The combination of liraglutide and phentermine, at 100 μg/kg/day and 10 mg/kg/day, respectively, produced the largest reduction in body weight in both lean and diet-induced obese (DIO) mice, when compared with both vehicle and monotherapy-treated mice. In lean mice, combination treatment at the aforementioned doses significantly increased heart rate and reduced blood pressure, whereas in DIO mice, combination therapy induced a transient increase in heart rate and decreased blood pressure. These studies demonstrate that in obese mice, the combination of liraglutide and phentermine may reduce body weight but only induce modest improvements in cardiovascular functions. Conversely, in lean mice, the additional weight loss from combination therapy does not improve cardiovascular parameters.
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Affiliation(s)
- Stephanie E Simonds
- Metabolic Disease and Obesity Program, Monash Biomedicine Discovery Institute, and Department of Physiology, Monash University, Melbourne, Victoria, Australia
| | - Jack T Pryor
- Metabolic Disease and Obesity Program, Monash Biomedicine Discovery Institute, and Department of Physiology, Monash University, Melbourne, Victoria, Australia
- Woodrudge LTD, London, U.K
| | | | - Alberte S Buch-Rasmussen
- Metabolic Disease and Obesity Program, Monash Biomedicine Discovery Institute, and Department of Physiology, Monash University, Melbourne, Victoria, Australia
| | - Lauren E Kelly
- Metabolic Disease and Obesity Program, Monash Biomedicine Discovery Institute, and Department of Physiology, Monash University, Melbourne, Victoria, Australia
| | | | - Michael A Cowley
- Metabolic Disease and Obesity Program, Monash Biomedicine Discovery Institute, and Department of Physiology, Monash University, Melbourne, Victoria, Australia
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Carter LP, Henningfield JE, Wang YG, Lu Y, Kelsh D, Vince B, Sellers E. A randomized, double-blind, placebo-controlled, crossover study to evaluate the human abuse liability of solriamfetol, a selective dopamine and norepinephrine reuptake inhibitor. J Psychopharmacol 2018; 32:1351-1361. [PMID: 30269642 PMCID: PMC6247449 DOI: 10.1177/0269881118796814] [Citation(s) in RCA: 172] [Impact Index Per Article: 28.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND This study evaluated the human abuse potential of solriamfetol (formerly JZP-110), a selective dopamine and norepinephrine reuptake inhibitor with robust wake-promoting effects. METHODS Adults with a recent history of recreational polydrug use, including stimulants, and who met criteria in a Qualification Phase were randomized to one of six sequences in a Test Phase. Each Test Phase sequence included a single administration of placebo, solriamfetol (300, 600, and 1200 mg), and phentermine (45 and 90 mg), with a two-day washout between periods. The primary endpoint was peak rating ( Emax) of Liking at the Moment across the first 12 h on a liking/disliking visual analog scale; key secondary endpoints were Next Day Overall Drug Liking, how much the participant would like to Take the Drug Again, and positive and negative subjective effects. Safety was also assessed throughout the study. RESULTS Of 43 participants (74.4% male; mean age 29.3 years), 37 completed the study. Peak Emax Liking at the Moment for all solriamfetol doses was significantly greater than placebo and significantly less than phentermine 90 mg ( p < 0.05). Overall Next Day Drug Liking was greater than placebo for solriamfetol 300 mg and phentermine 45 and 90 mg ( p < 0.05). Willingness to Take the Drug Again was significantly greater than placebo and significantly less than both doses of phentermine for all doses of solriamfetol ( p < 0.05). Ratings of negative subjective effects (bad effects, disliking, anxiety, agitation) were higher with solriamfetol 600 and 1200 mg relative to phentermine. The most common treatment-emergent adverse events with solriamfetol were hypervigilance, elevated mood, dry mouth, hyperhidrosis, and insomnia. CONCLUSION Solriamfetol appears to have abuse potential similar to or lower than phentermine.
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Affiliation(s)
- Lawrence P Carter
- Jazz Pharmaceuticals, Palo Alto, CA,
USA
- Department of Pharmacology &
Toxicology, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Jack E Henningfield
- Pinney Associates, Bethesda, MD,
USA
- Department of Psychiatry and Behavioral
Sciences, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | | | - Yuan Lu
- Jazz Pharmaceuticals, Palo Alto, CA,
USA
| | - Debra Kelsh
- Vince & Associates Clinical
Research, Overland Park, KS, USA
| | - Bradley Vince
- Vince & Associates Clinical
Research, Overland Park, KS, USA
| | - Edward Sellers
- Department of Pharmacology and
Toxicology, Medicine, and Psychiatry, University of Toronto, ON, Canada
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Affiliation(s)
| | - Ba D Nguyen
- Department of Radiology, Mayo Clinic, Scottsdale, AZ.
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8
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Rebello C, Nikonova EV, Zhou S, Aronne LJ, Fujioka K, Garvey WT, Smith SR, Coulter AA, Greenway FL. Effect of Lorcaserin Alone and in Combination with Phentermine on Food Cravings After 12-Week Treatment: A Randomized Substudy. Obesity (Silver Spring) 2018; 26:332-339. [PMID: 29363287 PMCID: PMC5788290 DOI: 10.1002/oby.22094] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 11/16/2017] [Accepted: 11/16/2017] [Indexed: 12/19/2022]
Abstract
OBJECTIVE This study evaluated the effect of lorcaserin 10 mg twice daily (LOR BID), or with phentermine 15 mg once daily (LOR BID + PHEN QD) and 15 mg twice daily (LOR BID + PHEN BID), in conjunction with energy restriction on food cravings. METHODS Two hundred and thirty-five patients without diabetes but with obesity or overweight and ≥ 1 comorbidity received LOR BID, LOR BID + PHEN QD, or LOR BID + PHEN BID for 12 weeks in a randomized double-blind study. The Food Craving Inventory (FCI) and the Control of Eating Questionnaire (COEQ) were administered over 12 weeks. RESULTS The FCI total score and the subscale scores reduced from baseline in all groups. The least squares means (95% confidence intervals) for the total scores were -0.65 (-0.75 to -0.55), -0.75 (-0.84 to -0.65), and -0.84 (-0.95 to -0.74) in the LOR BID, LOR BID + PHEN QD, and LOR BID + PHEN BID groups, respectively. Cravings assessed by COEQ reduced from baseline in all groups. In general, the combination treatments were more effective than lorcaserin alone. At week 12, except for fruit juice and dairy products, general and specific cravings reduced in LOR BID + PHEN BID compared with LOR BID (P < 0.05). CONCLUSIONS Lorcaserin in combination with phentermine improves control of food cravings during short-term energy restriction.
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Affiliation(s)
- Candida Rebello
- Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, LA, USA
| | - Elena V. Nikonova
- Eisai Medical and Scientific Affairs, Eisai Inc., Woodcliff Lake, NJ, USA
| | - Sharon Zhou
- Eisai Medical and Scientific Affairs, Eisai Inc., Woodcliff Lake, NJ, USA
| | - Louis J. Aronne
- Department of Medicine, Weill Cornell Medical College, NY, USA
| | - Ken Fujioka
- Department of Diabetes and Endocrinology, Scripps Clinic, La Jolla, CA, USA
| | - W. Timothy Garvey
- Department of Nutrition Sciences, University of Alabama at Birmingham, and the Birmingham VA Medical Center, Birmingham, Alabama, USA
| | - Steven R. Smith
- Center for the Metabolic Origins of Disease, Sanford Burnham Prebys Medical Discovery Institute, Orlando, Florida, USA
- Translational Research Institute for Metabolism and Diabetes, Florida Hospital, Orlando, Florida, USA
| | - Ann A. Coulter
- Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, LA, USA
| | - Frank L. Greenway
- Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, LA, USA
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Smith SR, Garvey WT, Greenway FL, Zhou S, Fain R, Pilson R, Fujioka K, Aronne LJ. Coadministration of lorcaserin and phentermine for weight management: A 12-week, randomized, pilot safety study. Obesity (Silver Spring) 2017; 25:857-865. [PMID: 28440045 PMCID: PMC5518190 DOI: 10.1002/oby.21811] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Revised: 01/07/2017] [Accepted: 01/30/2017] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To assess the short-term tolerability of lorcaserin alone or with two dose regimens of phentermine. METHODS This was a 12-week, randomized, double-blind, pilot safety study of N = 238 nondiabetic patients with obesity or overweight with ≥1 comorbidity randomized to lorcaserin 10 mg twice daily (BID; LOR BID) alone or with phentermine 15 mg once daily (QD; LOR BID+PHEN QD) or 15 mg twice daily (LOR BID+PHEN BID). Patients reporting ≥ 1 of 9 potentially serotonergic adverse events (AEs), mean weight loss (WL), and ≥5% WL are reported. RESULTS N = 238 were randomized, and N = 235 were treated. N = 94 reported potentially serotonergic AEs: 37.2% LOR BID, 42.3% LOR BID+PHEN QD, and 40.5% LOR BID+PHEN BID. AEs leading to discontinuation were reported approximately twice as often in the LOR BID+PHEN BID group versus the LOR BID group. Mean WL was 3.5 kg/3.3%, 7.0 kg/6.7%, and 7.6 kg/7.2% for LOR BID, LOR BID+PHEN QD, and LOR BID+PHEN BID, respectively. At least 5% WL was achieved by 28.2% LOR BID, 59.0% LOR BID+PHEN QD (P = 0.0002 vs. LOR BID), and 70.9% LOR BID+PHEN BID (P < 0.0001 vs. LOR BID) patients. CONCLUSIONS Phentermine added to lorcaserin enhanced short-term weight loss but did not increase incidence of potentially serotonergic AEs; however, phentermine twice daily increased discontinuation compared to both lorcaserin alone and lorcaserin plus phentermine once daily.
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Affiliation(s)
- Steven R. Smith
- Center for the Metabolic Origins of Disease, Sanford Burnham Prebys Medical Discovery InstituteOrlandoFloridaUSA
- Translational Research Institute for Metabolism and Diabetes, Florida Hospital, OrlandoFloridaUSA
| | - W. Timothy Garvey
- Department of Nutrition SciencesUniversity of Alabama at Birmingham, and the Birmingham VA Medical Center, BirminghamAlabamaUSA
| | - Frank L. Greenway
- Pennington Biomedical Research CenterLouisiana State University SystemBaton RougeLouisianaUSA
| | - Sharon Zhou
- Eisai Medical and Scientific Affairs, Eisai Inc.Woodcliff LakeNew JerseyUSA
| | - Randi Fain
- Formerly Eisai Inc.Woodcliff LakeNew JerseyUSA
| | | | - Ken Fujioka
- Department of Diabetes and EndocrinologyScripps ClinicLa JollaCaliforniaUSA
| | - Louis J. Aronne
- Department of MedicineWeill Cornell Medical CollegeNew YorkNew YorkUSA
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10
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Lee PC, Dixon J. Pharmacotherapy for obesity. Aust Fam Physician 2017; 46:472-477. [PMID: 28697290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
BACKGROUND Obesity is a serious, chronic, relapsing disease of energy regulation, with strong genetic and early-life environmental determinants. Pharmacotherapy can be a useful adjunct to lifestyle intervention in effecting and maintaining clinically meaningful weight loss. OBJECTIVE The aim of this article is to discuss the role of pharmacotherapy in obesity management. The efficacy, side effects and contraindications of available weight-loss medications are reviewed. DISCUSSION Long-term pharmacotherapy options, which can be effective in providing moderate weight loss, are available to treat obesity. Pharma-cotherapy should be considered an adjunct to lifestyle intervention in those with a body mass index (BMI) >30 kg/m30 kg/m2, or in those with a BMI of 27-30 kg/m2 and obesity-related complications. Safety and efficacy should be monitored closely on commencement, and the medication should be discontinued if there are safety or tolerability issues, or if.
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11
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In brief: Phentermine (Lomaira) for weight loss. Med Lett Drugs Ther 2016; 58:158. [PMID: 27906152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
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Azebu LM. The FDA's risk/benefit calculus in the approvals of Qsymia and Belviq: treating an obesity epidemic while avoiding another fen-phen. Food Drug Law J 2014; 69:87-iii. [PMID: 24772687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
As obesity rates continue to rise in the United States, both physicians and patients have demanded more safe and effective drug treatment options. However, following the fen-phen/Redux and sibutramine failures, the FDA has been hesitant to approve any anti-obesity drugs, despite the magnitude of the epidemic. Some have argued that these public embarrassments have led the FDA to overestimate the risks and underestimate the benefits when deciding whether to approve new anti-obesity drugs. On June 27, 2012, the FDA approved Belviq for chronic weight management, making it the first anti-obesity drug approved by the FDA in thirteen years. Less than one month later, the FDA approved Qsymia for the treatment of obesity. Both drugs had been denied FDA approval less than two years earlier. In this paper, I will first review the obesity crisis and discuss the high-profile market withdrawals of fenfluramine, dexfenfluramine, and sibutramine. Second, I will explain the FDA's drug approval process with a focus on the FDA's risk/benefit calculus. Third, I will compare the FDA's risk/benefit analysis for Qsymia and Belviq in 2010 with the agency's risk/benefit analysis in 2012 to determine what caused the agency to grant approval in 2012 while denying it in 2010. Finally, I will analyze what these drug approvals may mean for the future of other anti-obesity drugs.
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Abstract
BACKGROUND AND OBJECTIVE Very few drugs are approved for obesity treatment by regulatory agencies. Very recently phentermine/topiramate controlled-release [PHEN/TPM CR; (Qsymia®)] obtained Food and Drug Administration (FDA) approval as an addition to a reduced-calorie diet and exercise for chronic weight management. Our aim was to review the available clinical evidence on weight loss, metabolic effects and adverse events associated with use of this product. METHODS Randomized controlled trials with phentermine/topiramate controlled-release were selected through a Medline search using the terms: phentermine and topiramate, phentermine and controlled release topiramate, new anti-obesity drugs and phentermine/topiramate, recent combinations of anti-obesity drugs and Qnexa®. RESULTS PHEN/TPM CR was associated with a weight loss of 8.1-10.9 % (mid and high dose, respectively), while patients in placebo groups lost 1.4-1.8 % of their initial weight. PHEN/TPM CR also resulted in a significant decrease of waist circumference. Weight loss with PHEN/TPM CR was associated with a decrease in blood pressure but with a slight increase in the heart rate. Furthermore, in all trials it exerted favorable effects on lipid profile, especially on triglycerides and high-density lipopoprotein (HDL) cholesterol. PHEN/TPM CR treatment also improved insulin sensitivity and glycemia. Moreover, it decreased significantly progression to type 2 diabetes. In all of the studies the severe adverse events were similar between the control groups and the groups of PHEN/TPM CR. The most frequent side-effects observed in the active treatment group were paresthesia, dysgeusia, dry mouth, constipation and insomnia. WHAT IS NEW AND CONCLUSION PHEN/TPM CR combined with lifestyle modification may be an effective and well-tolerated treatment for obesity and weight-related metabolic complications. Its long-term efficacy and safety have yet to be defined.
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Affiliation(s)
- Dimitrios N Kiortsis
- Laboratory of Physiology, Medical School, University of Ioannina, Ioannina, Greece
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Abstract
Obesity, defined as a body mass index (BMI, kg/m(2) ) >30, is a significant public health problem. It's estimated that 50 percent of the U.S. population will be classified as obese by the year 2030. Due to associated health complications and rising health care costs related to obesity, new treatment options are being explored. For people who need additional treatment beyond lifestyle modification, new pharmacologic options have been developed that may assist in reducing BMI. Health care providers and patients should consider each person's individual health history and consider both the potential risks and benefits of these therapies.
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Affiliation(s)
- Heidi Collins Fantasia
- Department of Nursing, School of Health and Environment, University of Massachusetts, Lowell, MA, USA.
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15
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Wynn RL. Diet drugs Belviq and Qsymia receive FDA approval: what dentists need to know. Gen Dent 2013; 61:11-13. [PMID: 23302354] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Affiliation(s)
- Richard L Wynn
- Department of Oral Craniofacial Biological Sciences, Dental School, University of Maryland, Baltimore, USA
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16
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Allison DB, Gadde KM, Garvey WT, Peterson CA, Schwiers ML, Najarian T, Tam PY, Troupin B, Day WW. Controlled-release phentermine/topiramate in severely obese adults: a randomized controlled trial (EQUIP). Obesity (Silver Spring) 2012; 20:330-42. [PMID: 22051941 PMCID: PMC3270297 DOI: 10.1038/oby.2011.330] [Citation(s) in RCA: 385] [Impact Index Per Article: 32.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Accepted: 09/24/2011] [Indexed: 12/25/2022]
Abstract
A 56-week randomized controlled trial was conducted to evaluate safety and efficacy of a controlled-release combination of phentermine and topiramate (PHEN/TPM CR) for weight loss (WL) and metabolic improvements. Men and women with class II and III obesity (BMI ≥ 35 kg/m(2)) were randomized to placebo, PHEN/TPM CR 3.75/23 mg, or PHEN/TPM CR 15/92 mg, added to a reduced-energy diet. Primary end points were percent WL and proportions of patients achieving 5% WL. Secondary end points included waist circumference (WC), systolic and diastolic blood pressure (BP), fasting glucose, and lipid measures. In the primary analysis (randomized patients with at least one postbaseline weight measurement who took at least one dose of assigned drug or placebo), patients in the placebo, 3.75/23, and 15/92 groups lost 1.6%, 5.1%, and 10.9% of baseline body weight (BW), respectively, at 56 weeks (P < 0.0001). In categorical analysis, 17.3% of placebo patients, 44.9% of 3.75/23 patients, and 66.7% of 15/92 patients, lost at least 5% of baseline BW at 56 weeks (P < 0.0001). The 15/92 group had significantly greater changes relative to placebo for WC, systolic and diastolic BP, fasting glucose, triglycerides, total cholesterol, low-density lipoprotein (LDL), and high-density lipoprotein (HDL). The most common adverse events were paresthesia, dry mouth, constipation, dysgeusia, and insomnia. Dropout rate from the study was 47.1% for placebo patients, 39.0% for 3.75/23 patients, and 33.6% of 15/92 patients. PHEN/TPM CR demonstrated dose-dependent effects on weight and metabolic variables in the direction expected to be beneficial with no evidence of serious adverse events induced by treatment.
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Affiliation(s)
- David B Allison
- Department of Biostatistics, School of Public Health and Nutrition Obesity Research Center, University of Alabama at Birmingham, Birmingham, Alabama, USA.
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17
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Garvey WT, Ryan DH, Look M, Gadde KM, Allison DB, Peterson CA, Schwiers M, Day WW, Bowden CH. Two-year sustained weight loss and metabolic benefits with controlled-release phentermine/topiramate in obese and overweight adults (SEQUEL): a randomized, placebo-controlled, phase 3 extension study. Am J Clin Nutr 2012; 95:297-308. [PMID: 22158731 PMCID: PMC3260065 DOI: 10.3945/ajcn.111.024927] [Citation(s) in RCA: 404] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Accepted: 11/15/2011] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Obesity is a serious chronic disease. Controlled-release phentermine/topiramate (PHEN/TPM CR), as an adjunct to lifestyle modification, has previously shown significant weight loss compared with placebo in a 56-wk study in overweight and obese subjects with ≥2 weight-related comorbidities. OBJECTIVE This study evaluated the long-term efficacy and safety of PHEN/TPM CR in overweight and obese subjects with cardiometabolic disease. DESIGN This was a placebo-controlled, double-blind, 52-wk extension study; volunteers at selected sites continued with original randomly assigned treatment [placebo, 7.5 mg phentermine/46 mg controlled-release topiramate (7.5/46), or 15 mg phentermine/92 mg controlled-release topiramate (15/92)] to complete a total of 108 wk. All subjects participated in a lifestyle-modification program. RESULTS Of 866 eligible subjects, 676 (78%) elected to continue in the extension. Overall, 84.0% of subjects completed the study, with similar completion rates between treatment groups. At week 108, PHEN/TPM CR was associated with significant, sustained weight loss (intent-to-treat with last observation carried forward; P < 0.0001 compared with placebo); least-squares mean percentage changes from baseline in body weight were -1.8%, -9.3%, and -10.5% for placebo, 7.5/46, and 15/92, respectively. Significantly more PHEN/TPM CR-treated subjects at each dose achieved ≥5%, ≥10%, ≥15%, and ≥20% weight loss compared with placebo (P < 0.001). PHEN/TPM CR improved cardiovascular and metabolic variables and decreased rates of incident diabetes in comparison with placebo. PHEN/TPM CR was well tolerated over 108 wk, with reduced rates of adverse events occurring between weeks 56 and 108 compared with rates between weeks 0 and 56. CONCLUSION PHEN/TPM CR in conjunction with lifestyle modification may provide a well-tolerated and effective option for the sustained treatment of obesity complicated by cardiometabolic disease. This trial was registered at clinicaltrials.gov as NCT00796367.
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Affiliation(s)
- W Timothy Garvey
- Department of Nutrition Sciences, UAB Diabetes Research and Training Center, University of Alabama at Birmingham, 35294-3360, USA.
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Hendricks EJ, Greenway FL, Westman EC, Gupta AK. Blood pressure and heart rate effects, weight loss and maintenance during long-term phentermine pharmacotherapy for obesity. Obesity (Silver Spring) 2011; 19:2351-60. [PMID: 21527891 DOI: 10.1038/oby.2011.94] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
There is a perception that phentermine pharmacotherapy for obesity increases blood pressure and heart rate (HR), exposing treated patients to increased cardiovascular risk. We collected data from phentermine-treated (PT) and phentermine-untreated (P0) patients at a private weight management practice, to examine blood pressure, HR, and weight changes. Records of 300 sequential returning patients were selected who had been treated with a low-carbohydrate ketogenic diet if their records included complete weight, blood pressure, and HR data from seven office examinations during the first 12 weeks of therapy. The mean time in therapy, time range, and mode was 92 (97.0), 12-624, and 52 weeks. 14% were normotensive, 52% were prehypertensive, and 34% were hypertensive at their first visit or had a previous diagnosis of hypertension. PT subjects systolic blood pressure/diastolic blood pressure (SBP/DBP) declined from baseline at all data points (SBP/DBP -6.9/-5.0 mm Hg at 26, and -7.3/-5.4 at 52 weeks). P0 subjects' declines of SBP/DBP at both 26 and 52 weeks were -8.9/-6.3 but the difference from the treated cohort was not significant. HR changes in treated/untreated subjects at weeks 26 (-0.9/-3.5) and 52 (+1.2/-3.6) were not significant. Weight loss was significantly greater in the PT cohort for week 1 through 104 (P = 0.0144). These data suggest phentermine treatment for obesity does not result in increased SBP, DBP, or HR, and that weight loss assisted with phentermine treatment is associated with favorable shifts in categorical blood pressure and retardation of progression to hypertension in obese patients.
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Affiliation(s)
- Ed J Hendricks
- The Center for Weight Management, Roseville, California, USA.
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Aronne LJ, Halseth AE, Burns CM, Miller S, Shen LZ. Enhanced weight loss following coadministration of pramlintide with sibutramine or phentermine in a multicenter trial. Obesity (Silver Spring) 2010; 18:1739-46. [PMID: 20094043 DOI: 10.1038/oby.2009.478] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Preclinical evidence suggests that pharmacotherapy for obesity using combinations of agents targeted at distinct regulatory pathways may produce robust additive or synergistic effects on weight loss. This randomized placebo-controlled trial examined the safety and efficacy of the amylin analogue pramlintide alone or in combination with either phentermine or sibutramine. All patients also received lifestyle intervention. Following a 1-week placebo lead-in, 244 obese or overweight, nondiabetic subjects (88% female; 41 +/- 11 years; BMI 37.7 +/- 5.4 kg/m(2); weight 103 +/- 19 kg; mean +/- s.d.) received placebo subcutaneously (sc) t.i.d., pramlintide sc (120 microg t.i.d.), pramlintide sc (120 microg t.i.d.) + oral sibutramine (10 mg q.a.m.), or pramlintide sc (120 microg t.i.d.) + oral phentermine (37.5 mg q.a.m.) for 24 weeks. Treatment was single-blind for subjects receiving subcutaneous medication only and open-label for subjects in the combination arms. Weight loss achieved at week 24 with either combination treatment was greater than with pramlintide alone or placebo (P < 0.001; 11.1 +/- 1.1% with pramlintide + sibutramine, 11.3 +/- 0.9% with pramlintide + phentermine, -3.7 +/- 0.7% with pramlintide; -2.2 +/- 0.7% with placebo; mean +/- s.e.). Elevations from baseline in heart rate and diastolic blood pressure were demonstrated with both pramlintide + sibutramine (3.1 +/- 1.2 beats/min, P < 0.05; 2.7 +/- 0.9 mm Hg, P < 0.01) and pramlintide + phentermine (4.5 +/- 1.3 beats/min, P < 0.01; 3.5 +/- 1.2 mm Hg, P < 0.001) using 24-h ambulatory monitoring. However, the majority of subjects receiving these treatments remained within normal blood pressure ranges. These results support the potential of pramlintide-containing combination treatments for obesity.
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20
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Abstract
Elevations in plasma serotonin (5-HT) have been implicated in the pathogenesis of cardiac and pulmonary disease. Normally, plasma 5-HT concentrations are kept low by transporter-mediated uptake of 5-HT into platelets and by metabolism to 5-hydroxyindoleacetic acid (5-HIAA). Many abused drugs (e.g., substituted amphetamines) and prescribed medications (e.g., fluoxetine) target 5-HT transporters and could thereby influence circulating 5-HT. We evaluated the effects of amphetamines analogs [(+/-)-fenfluramine, (+/-)-3,4-methylenedioxymethamphetamine, (+)-methamphetamine, (+)-amphetamine, phentermine] on extracellular levels (i.e., plasma levels) of 5-HT and 5-HIAA in blood from catheterized rats. Effects of the 5-HT uptake blocker fluoxetine were examined for comparison. Drugs were tested in vivo and in vitro; plasma indoles were measured using a novel microdialysis method in whole blood. We found that baseline dialysate levels of 5-HT are approximately 0.22 nM, and amphetamine analogs evoke large dose-dependent increases in plasma 5-HT ranging from 4 to 20 nM. The ability of drugs to elevate plasma 5-HT is positively correlated with their potency as 5-HT transporter substrates. Fluoxetine produced small, but significant, increases in plasma 5-HT. Although the drug-evoked 5-HT concentrations are below the micromolar levels required for contraction of pulmonary arteries, they approach concentrations reported to stimulate mitogenesis in pulmonary artery smooth muscle cells. Additional studies are needed to determine the effects of chronic administration of amphetamines on circulating 5-HT.
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Affiliation(s)
- Dorota Zolkowska
- Clinical Psychopharmacology Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, 5500 Nathan Shock Drive, Baltimore, MD 21224, USA
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Rohrbach KW, Han S, Gan J, O'Tanyi EJ, Zhang H, Chi CL, Taub R, Largent BL, Cheng D. Disconnection between the early onset anorectic effects by C75 and hypothalamic fatty acid synthase inhibition in rodents. Eur J Pharmacol 2005; 511:31-41. [PMID: 15777777 DOI: 10.1016/j.ejphar.2005.01.034] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2004] [Accepted: 01/18/2005] [Indexed: 10/25/2022]
Abstract
In order to explore the relationship between the anorectic effect of 3-carboxy-4-octyl-2-methylenebutyrolactone (C75) and its pharmacokinetic properties, studies of in vivo and in vitro pharmacological characterization of C75 were performed in Fischer rats. In a quantitative measurement of food intake, we determined that appetite suppression by C75 takes place within 4 h. The C(max) for C75 of 2.6+/-1.5 microM was reached within 1-4 h after intraperitoneal administration at 30 mg/kg, a drug level that causes complete blockade of food intake. However, this concentration is substantially lower than the effective concentration used to inhibit rat fatty acid synthase enzyme activity in vitro (IC50: approximately 200 microM) and hypothalamic enzyme activity was found not to be inhibited by intraperitoneal administration of C75 at 30 mg/kg. Instead, a dramatic induction of c-Fos expression was found in area postrema. Collectively, these data indicate that the anorectic effect of C75 is independent of its inhibition of fatty acid synthase in the hypothalamus.
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Affiliation(s)
- Kenneth W Rohrbach
- Pharmaceutical Research Institute, Department of Metabolic Disease, Bristol-Myers Squibb Company, Princeton, NJ 08543, USA
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22
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Abstract
The effects of two anorectic drugs, dexfenfluramine and phentermine, on food intake under different food-access conditions were examined. Experiment 1 compared the effects of these drugs on food intake under a progressive-ratio (PR) schedule and free-access conditions. Dexfenfluramine decreased food intake under both conditions, but the doses required to decrease intake under free-access conditions were higher than those required to reduce intake under the PR condition. Intermediate doses of phentermine sometimes increased breaking points, and higher doses decreased them. Phentermine decreased food intake at the same doses under both access conditions. Thus the potency of dexfenfluramine, but not phentermine, to decrease food-maintained behavior depended upon the food-access condition. Experiment 2 used a novel mixed progressive-ratio schedule of food delivery to study the duration of drug effects. Sessions consisted of five components separated by 3-hr timeouts. The ratio requirement reset at the beginning of each component and a new breaking point was obtained. Both dexfenfluramine and phentermine dose-dependently decreased breaking points early in the session. In some rats, compensatory increases in breaking point were observed. That is, breaking points later in the session increased over control levels, resulting in no change in the total number of food pellets earned for the session compared to control. The present findings suggest that the effects of some anorectic drugs depend upon the access conditions for food; increasing the effort to obtain food may enhance their ability to decrease food-maintained behavior.
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Affiliation(s)
- Mark G LeSage
- Louisiana State University Health Sciences Center in Shreveport, USA.
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Ferrer-Lorente R, Cabot C, Fernández-López JA, Remesar X, Alemany M. Effects of oleoyl-estrone with dexfenfluramine, sibutramine or phentermine on overweight rats. Eur J Pharmacol 2005; 513:243-8. [PMID: 15862807 DOI: 10.1016/j.ejphar.2005.02.044] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2004] [Revised: 11/26/2004] [Accepted: 02/25/2005] [Indexed: 10/25/2022]
Abstract
We studied the combination of oleoyl-estrone with either dexfenfluramine, sibutramine or phentermine in overweight male rats treated for 10 days in order to determine whether they shared a mechanism of action. Oleoyl-estrone, dexfenfluramine and sibutramine decreased body weight and energy (essentially lipids); losses were higher when combined with oleoyl-estrone. Glycemia was maintained except under phentermine; oleoyl-estrone induced decreases in triacylglycerols, cholesterol, insulin and HOMA (homeostasis model assessment). Combination of oleoyl-estrone and sibutramine resulted in the loss of up to 29% body energy in 10 days. Energy expenditure was maintained. The effects of oleoyl-estrone and dexfenfluramine or sibutramine on appetite were substantially additive. All oleoyl-estrone-treated rats showed increased insulin sensitivity. In conclusion, combined treatment of overweight rats with oleoyl-estrone and sibutramine or dexfenfluramine results in a dramatic loss of weight and fat, whilst maintaining circulating energy homoeostasis.
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Affiliation(s)
- Raquel Ferrer-Lorente
- Department of Nutrition and Food Science, Faculty of Biology, University of Barcelona, Av. Diagonal, 645, 08028 Barcelona, Spain
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Alexander M, Rothman RB, Baumann MH, Endres CJ, Brasić JR, Wong DF. Noradrenergic and dopaminergic effects of (+)-amphetamine-like stimulants in the baboonPapio anubis. Synapse 2005; 56:94-9. [PMID: 15729739 DOI: 10.1002/syn.20126] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
(+)-Amphetamine, (+/-)-ephedrine, and phentermine are commonly used appetite suppressants that release monoamines from nerve cells by acting as substrates for biogenic amine transporters. One key difference among the three drugs is their selectivity for norepinephrine (NE) release vs. dopamine (DA) release. The NE/DA selectivity ratios for these drugs as determined in vitro [(EC50 NE(-1))/(EC50 DA(-1))] are (+/-)-ephedrine (18.6) > phentermine (6.7) > (+)-amphetamine (3.5). The in vitro data suggest that when administered in vivo, these stimulants might differ in their ability to release DA from nerve terminals in the brain. To test this hypothesis, noradrenergic effects (i.e., plasma NE) and dopaminergic effects (i.e., central DA release) were assessed when each drug was administered intravenously (1.5 mg/kg) to anesthetized baboons. Central DA release was determined via positron emission tomography using the method of [11C]raclopride displacement. In the present investigation, high doses of these stimulants increased plasma NE and DA in parallel, but only (+)-amphetamine released central DA from neurons and decreased plasma prolactin. None of the drugs altered plasma amine metabolite levels, indicating no inhibition of monoamine oxidase activity at the administered doses. Plasma drug levels measured in baboons were higher than those measured in human patients taking prescribed doses of the drugs. Viewed collectively, the present data indicate that typical clinical doses of phentermine and (+/-)-ephedrine may not release central DA in humans, a hypothesis that should ultimately be tested in controlled clinical studies.
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Affiliation(s)
- Mohab Alexander
- Division of Nuclear Medicine, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA
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Anisimov VN, Ukraintseva SV, Anikin IV, Popovich IG, Zabezhinski MA, Bertsein LM, Arutjunyan AV, Ingram DK, Lane MA, Roth GS. Effects of Phentermine and Phenformin on Biomarkers of Aging in Rats. Gerontology 2004; 51:19-28. [PMID: 15591752 DOI: 10.1159/000081430] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2003] [Accepted: 02/24/2004] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Caloric restriction (CR) is the only treatment known to substantially prolong both average and maximal life span in experimental animals. Interventions that mimic certain effects of CR could be potential anti-aging treatments in humans. Drugs which reduce appetite (anorexiants) represent one class of candidate treatments. Agents that reduce the glucose utilization by the organism could also represent another class of candidate CR mimetics. OBJECTIVE In our study, we addressed the following questions: (1) Does treatment with an anorexiant reduce caloric intake and body weight of experimental animals comparable to that caused by CR? (2) Does treatment with an antidiabetic agent influence caloric intake and body weight? (3) Does treatment with any of these drugs affect metabolic parameters of an organism in the way similar to that observed with CR? METHODS One hundred and twenty 6-month-old female Wistar-derived LIO rats were randomly subdivided into four groups and exposed to: (1) ad libitum feeding with placebo (controls); (2) the antidiabetic drug phenformin (2 mg/kg); (3) the anorectic drug phentermine (1 mg/kg), and (4) the same amount of food as the group with the least food intake during the previous week (pair-fed controls). Food and water intake, body weight, and rectal temperature were measured weekly during 16 weeks. At the end of the 16th week of the experiment, serum levels of glucose, total beta-lipoprotein and pre-beta-lipoprotein fractions, cholesterol, triglycerides, insulin, total triiodothyronine, and free thyroxine were estimated. The contents of diene conjugates and Schiff's bases, total antioxidant activity, the activities of Cu/Zn superoxide dismutase, glutathione S-transferase, and glutathione peroxidase, and the generation of reactive oxygen species (ROS) were studied in brain and liver homogenates and in the serum. RESULTS The controls exposed to pair feeding had a significantly reduced food consumption (about 20%) as compared with the ad libitum fed controls and thus exhibited a moderate CR. Treatment with phentermine reduced the caloric intake by about 12% as compared with the ad libitum fed controls. Body weight and water intake in this group were only slightly decreased (by about 2 and 5%, respectively) as compared with the controls. The mean rectal temperature in the phentermine group (38 degrees C) was significantly higher than in the ad libitum fed (37.8 degrees C) and pair-fed (37.6 degrees C) controls. Treatment with phentermine also resulted in significantly reduced ROS levels in all tissues studied, while the highest ROS production was found in ad libitum (blood serum) and pair-fed (brain) controls. Treatment with phenformin did not significantly influence food and water consumption, body weight, and temperature when compared with the ad libitum fed controls. Rats treated with this antidiabetic drug showed intermediate values of ROS generation. Differences among the groups in total antioxidant activity were not obvious. CONCLUSIONS Treatment with phentermine reduces caloric intake slightly less than is commonly observed in CR studies. CR due to forcibly reduced feeding and CR due to substance-suppressed appetite appear to act through different metabolic mechanisms and thus may affect aging and longevity in different ways.
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Affiliation(s)
- Vladimir N Anisimov
- N.N. Petrov Research Institute of Oncology, D.O. Ott Research Institute of Obstetrics and Gynecology, St. Petersburg, Russia.
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Johnson GJ, Leis LA, Dunlop PC, Weir EK. The effect of the anorectic agent, d-fenfluramine, and its primary metabolite, d-norfenfluramine, on intact human platelet serotonin uptake and efflux. J Thromb Haemost 2003; 1:2663-8. [PMID: 14675103 DOI: 10.1046/j.1538-7836.2003.00474.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Dexfenfluramine, a drug formerly prescribed for treatment of obesity, caused heart valve damage and pulmonary hypertension in some people. The cause of the toxicity has not been defined, but 5-HT has been implicated. The objective of this study was to evaluate the effect of the anorectic agent, d-fenfluramine, and its major metabolite, d-norfenfluramine, on intact human platelet serotonin (5-HT) transport in vitro. The effects of d-fenfluramine and d-norfenfluramine on platelet uptake and efflux of 3H-5-HT were measured in buffer at pH 6.7, to optimize serotonin transporter (SERT) function, and at pH 7.4. Uptake of 3H-5-HT at pH 6.7 and 7.4 was inhibited by both agents at micro m concentrations (IC50, d-fenfluramine approximately 3 microM; d-norfenfluramine approximately 10 microM). However, no efflux of 3H-5-HT from labeled platelets at either pH 6.7 or 7.4 occurred at similar concentrations of d-fenfluramine or d-norfenfluramine. With inhibition of platelet dense granule 3H-5-HT uptake by reserpine, efflux of 3H-5-HT was observed at pH 6, but not at pH 7.4. Fluoxetine, a SERT inhibitor, was a more potent inhibitor of uptake (IC50 0.05 microM) than d-fenfluramine, but the anorectic agent, phentermine, had no effect. Therefore, d-fenfluramine and d-norfenfluramine inhibit human platelet uptake of 5-HT in vitro at tissue concentrations attainable in vivo, but they do not stimulate 5-HT efflux due to dense granule sequestration. Inhibition of platelet 5-HT uptake may play a role in the cardiopulmonary toxicity of d-fenfluramine, but other factors probably contribute, since similar toxicity has not been observed with fluoxetine.
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Affiliation(s)
- G J Johnson
- Hematology/Oncology Section, Medical Service, Minneapolis Veterans Affairs Medical Center, and Department of Medicine, University of Minnesota, Minneapolis, 55417, USA.
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Wellman PJ, Jones SL, Miller DK. Effects of preexposure to dexfenfluramine, phentermine, dexfenfluramine-phentermine, or fluoxetine on sibutramine-induced hypophagia in the adult rat. Pharmacol Biochem Behav 2003; 75:103-14. [PMID: 12759118 DOI: 10.1016/s0091-3057(03)00045-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The antiobesity drug sibutramine suppresses food intake via inhibition of reuptake of both norepinephrine (NE) and serotonin (5-HT) into brain terminals. The present study examined whether preexposure to other antiobesity drugs (fluoxetine [FLUOX], phentermine [PHEN], and dexfenfluramine [DEX]) that alter noradrenergic and/or serotonergic activity in brain induces tolerance or sensitization to the subsequent hypophagic action of sibutramine. Accordingly, adult male rats were treated (administered orally once per day for 21 days) with DEX (0, 1, or 3 mg/kg) and/or PHEN (0, 5, or 10 mg/kg), alone and in combination, or with the selective 5-HT reuptake inhibitor FLUOX (0, 15, or 30 mg/kg). Daily administration of PHEN persistently reduced food intake and body weight whereas tolerance developed to the hypophagic action of DEX or of FLUOX within the first week of daily administration. Moreover, low doses of DEX (1 mg/kg) and PHEN (5 mg/kg) interacted in a supra-additive manner to inhibit food intake and water intake and decrease body weight over the 21-day exposure period. After a recovery period of 9 days, a series of food intake trials were conducted to assess the hypophagic action of sibutramine (0, 1, 3, and 9 mg/kg po). Preexposure to PHEN (5 or 10 mg/kg), DEX (3 mg/kg), or FLUOX (30 mg/kg) resulted in a significant attenuation of the hypophagia induced by sibutramine over an 8-h, but not a 2-h, testing period. The pattern of cross-tolerance noted in this study is consistent with the observation that sibutramine inhibits eating via an interaction with noradrenergic and serotonergic mechanisms. Whether PHEN and DEX preexposure in humans alters subsequent sibutramine effectiveness is unknown.
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Affiliation(s)
- P J Wellman
- Department of Psychology, Texas A&M University, College Station, TX 77843-4235, USA.
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Tao R, Fray A, Aspley S, Brammer R, Heal D, Auerbach S. Effects on serotonin in rat hypothalamus of D-fenfluramine, aminorex, phentermine and fluoxetine. Eur J Pharmacol 2002; 445:69-81. [PMID: 12065196 DOI: 10.1016/s0014-2999(02)01751-x] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Hypothalamic 5-HT (serotonin) regulates food intake, energy expenditure and bodyweight. Using in vivo microdialysis, we determined the effects of various anorectic drugs on hypothalamic extracellular 5-HT levels during the dark phase when rats predominantly feed. Phentermine and aminorex, which were originally considered to be catecholaminergic drugs, markedly increased 5-HT efflux in rat hypothalamus. Their actions were less profound than D-fenfluramine, but considerably greater than that of the selective 5-HT reuptake inhibitor, fluoxetine. This suggests that enhanced hypothalamic 5-HT function could be involved in their anorectic actions. Pharmacological characterization revealed that D-fenfluramine, aminorex and probably also phentermine potentiate synaptic 5-HT function predominantly by release, whereas fluoxetine acts exclusively by reuptake inhibition. The results also revealed that the combined actions of phentermine and D-fenfluramine on hypothalamic extracellular 5-HT levels were additive, but not synergistic. In contrast, there was a significant negative cooperative effect on extraneuronal 5-HT of combining phentermine with fluoxetine.
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Affiliation(s)
- Rui Tao
- Nelson Laboratories, Department of Cell Biology and Neuroscience, Rutgers University, 604 Allison Road, Piscataway, NJ 08854-8082, USA
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Abstract
Recent studies with rat tissue preparations have suggested that the anorectic drug phentermine inhibits serotonin degradation by inhibition of monoamine oxidase (MAO) A with a K(I) value of 85-88 microM, a potency suggested to be similar to that of other reversible MAO inhibitors (Ulus et al., Biochem Pharmacol 2000;59:1611-21). Since there are known differences between rats and humans in substrate and inhibitor specificities of MAOs, the interactions of phentermine with recombinant human purified preparations of MAO A and MAO B were determined. Human MAO A was competitively inhibited by phentermine with a K(I) value of 498+/-60 microM, a value approximately 6-fold weaker than that observed for the rat enzyme. Phentermine was also observed to be a competitive inhibitor of recombinant human liver MAO B with a K(I) value of 375+/-42 microM, a value similar to that observed with the rat enzyme (310-416 microM). In contrast to the behavior with rat tissue preparations, no slow time-dependent behavior was observed for phentermine inhibition of purified soluble human MAO preparations. Difference absorption spectral studies showed similar perturbations of the covalent FAD moieties of both human MAO A and MAO B, which suggests a similar mode of binding in both enzymes. These data suggest that phentermine inhibition of human MAO A (or of MAO B) is too weak to be of pharmacological relevance.
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Affiliation(s)
- Ravi K Nandigama
- Department of Biochemistry, Emory University School of Medicine, Rollins Research Building, 1510 Clifton Road, Atlanta, GA 30322-3050, USA
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Prow MR, Lancashire B, Aspley S, Heal DJ, Kilpatrick IC. Additive effects on rat brain 5HT release of combining phentermine with dexfenfluramine. Int J Obes (Lond) 2001; 25:1450-3. [PMID: 11673764 DOI: 10.1038/sj.ijo.0801717] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2000] [Revised: 02/13/2001] [Accepted: 02/19/2001] [Indexed: 11/08/2022]
Abstract
OBJECTIVE AND DESIGN This study examined the effects of the anti-obesity agents, phentermine and dexfenfluramine given alone or in combination, on in vitro and in vivo 5HT release from rat brain tissue. RESULTS In vitro, phentermine was without effect on basal [3H]5HT efflux from hypothalamic slices whereas dexfenfluramine (10 microM) evoked a 131% increase in [3H]5HT release. In combination, the two drugs did not alter [3H]5HT release beyond that caused by dexfenfluramine alone. At pharmacologically equivalent doses, phentermine (5.7 mg/kg, i.p.) caused a rapid, modest elevation, and dexfenfluramine (3 mg/kg, i.p.) a larger but equally rapid elevation of extracellular 5HT in the microdialysates from the rat anterior hypothalamus. In combination, the increase in extracellular 5HT evoked by these drugs was not significantly greater than the sum of their individual effects. CONCLUSIONS This study provides evidence that phentermine's actions are not restricted to catecholamine systems and indicates that combining phentermine with dexfenfluramine results in an additive increase in neuronal 5HT release.
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Affiliation(s)
- M R Prow
- Knoll Limited, Research and Development, Nottingham, UK
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Kilpatrick IC, Traut M, Heal DJ. Monoamine oxidase inhibition is unlikely to be relevant to the risks associated with phentermine and fenfluramine: a comparison with their abilities to evoke monoamine release. Int J Obes (Lond) 2001; 25:1454-8. [PMID: 11673765 DOI: 10.1038/sj.ijo.0801732] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2000] [Revised: 03/02/2001] [Accepted: 03/27/2001] [Indexed: 12/14/2022]
Abstract
OBJECTIVE AND DESIGN It has been proposed that the anti-obesity agent, phentermine, may act in part via inhibition of monoamine oxidase (MAO). The ability of phentermine to inhibit both MAO(A) and MAO(B) in vitro has been examined along with that of the fenfluramine isomers, a range of selective serotonin reuptake inhibitors and sibutramine and its active metabolites. RESULTS In rat brain, harmaline and lazabemide showed potent and selective inhibition of MAO(A) and MAO(B), their respective target enzymes, with IC(50) values of 2.3 and 18 nM. In contrast, all other drugs examined were only weak inhibitors of MAO(A) and MAO(B) with IC(50) values for each enzyme in the moderate to high micromolar range. For MAO(A), the IC(50) for phentermine was estimated to be 143 microM, that for S(+)-fenfluramine, 265 microM and that for sertraline, 31 microM. For MAO(B), example IC(50)s were as follows: phentermine (285 microM), S(+)-fenfluramine (800 microM) and paroxetine (16 microM). Sibutramine was unable to inhibit either enzyme, even at its limit of solubility. CONCLUSION We therefore suggest that MAO inhibition is unlikely to play a role in the pharmacodynamic properties of any of the tested drugs, including phentermine. Instead, the lack of potency of these drugs as MAO inhibitors is contrasted with their powerful ability either to inhibit the uptake of one or more monoamines (fluoxetine, paroxetine, sertraline, sibutramine's active metabolites) or to evoke the release of one or more monoamines (S(+)-fenfluramine, S(+)-norfenfluramine, phentermine). These differences in mode of action may be linked to the adverse cardiovascular events experienced with some of the releasing agents.
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Abstract
The anorectic drug phentermine produces dose-related toxic effects on brain dopamine (DA) neurons in animals. Until recently, phentermine was widely used in combination with fenfluramine for purposes of appetite suppression and weight loss. With the recent withdrawal of fenfluramine from the market, many people have begun combining phentermine with fluoxetine, a serotonin reuptake inhibitor which also produces mild anorectic effects. Fluoxetine, in addition to inhibiting serotonin reuptake, inhibits hepatic mixed function oxidase, which plays an important role in the metabolic degradation of amphetamines. The purpose of the present study was to assess the effects of fluoxetine on the anorectic and DA neurotoxic effects of phentermine in mice. Phentermine, in combination with fluoxetine, produced greater reductions in food intake and body weight than phentermine alone. The phentermine/fluoxetine combination also produced greater long-term reductions in brain DA levels than phentermine alone, likely reflecting greater DA neurotoxicity of the drug combination. Brain concentrations of phentermine were also found to be higher in animals pretreated with fluoxetine. These findings indicate that fluoxetine potentiates both the anorectic and DA neurotoxic effects of phentermine, probably by increasing phentermine brain levels. The clinical significance of these findings remains to be ascertained.
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Affiliation(s)
- B T Callahan
- Department of Neurology, The Johns Hopkins Medical Institutions, Baltimore, Maryland 21224, USA
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Rowley HL, Butler SA, Prow MR, Dykes SG, Aspley S, Kilpatrick IC, Heal DJ. Comparison of the effects of sibutramine and other weight-modifying drugs on extracellular dopamine in the nucleus accumbens of freely moving rats. Synapse 2000; 38:167-76. [PMID: 11018791 DOI: 10.1002/1098-2396(200011)38:2<167::aid-syn8>3.0.co;2-w] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The acute effects of systemic administration of the anti-obesity agent sibutramine on extracellular dopamine (DA) in the nucleus accumbens of freely moving rats were studied using in vivo microdialysis and compared with the actions of phentermine and d-amphetamine at doses 1x and 3x their respective 2 h ED(50) values to reduce food intake in rats. At the lower dose, sibutramine did not elevate extracellular DA concentrations; however, at the higher dose (6.0 mg kg(-1), i.p.) it caused a modest and prolonged increase in extraneuronal DA. A maximal rise was observed at 60 min post-sibutramine treatment (+231% compared to controls) with DA levels remaining elevated for up to 160 min post treatment. In contrast, phentermine and d-amphetamine significantly enhanced DA efflux at both the lower and higher doses. These elevations of DA levels were significantly greater than that seen with the corresponding dose of sibutramine over 0-80 min post treatment. Maximal rises in DA levels resulting from the higher dose of each drug were +733% (phentermine, 3.9 mg kg(-1), i.p.) and +603% (d-amphetamine, 1.5 mg kg(-1), i.p.) compared to controls 40 min post treatment. The highest doses of phentermine and d-amphetamine increased rat locomotor activity up to 100 min and 160 min post treatment, respectively, whereas the equivalent sibutramine dose had no effect. These findings therefore suggest that dopaminergic reward mechanisms are not involved in the reduction of food intake by sibutramine. Furthermore, they are consistent with the view that sibutramine lacks abuse potential.
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Affiliation(s)
- H L Rowley
- BASF Pharma Research and Development, Nottingham, UK.
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Abstract
Phentermine was shown in the 1970s to inhibit the metabolism of serotonin by monoamine oxidase (MAO), but never was labeled as an MAO inhibitor; hence, it was widely used in combination with fenfluramine, and continues to be used, in violation of their labels, with other serotonin uptake blockers. We examined the effects of phentermine and several other unlabeled MAO inhibitors on MAO activities in rat lung, brain, and liver, and also the interactions of such drugs when administered together. Rat tissues were assayed for MAO-A and -B, using serotonin and beta-phenylethylamine as substrates. Phentermine inhibited serotonin-metabolizing (MAO-A) activity in all three tissues with K(i) values of 85-88 microM. These potencies were similar to those of the antidepressant MAO inhibitors iproniazid and moclobemide. When phentermine was mixed with other unlabeled reversible MAO inhibitors (e.g. pseudoephedrine, ephedrine, norephedrine; estradiol benzoate), the degree of MAO inhibition was additive. The cardiac valvular lesions and primary pulmonary hypertension that have been reported to be associated with fenfluramine-phentermine use may have resulted from the intermittent concurrent blockage of both serotonin uptake and metabolism.
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Affiliation(s)
- I H Ulus
- Department of Pharmacology and Clinical Pharmacology, Uludag University Medical School, Bursa, Turkey
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36
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Baumann MH, Ayestas MA, Dersch CM, Brockington A, Rice KC, Rothman RB. Effects of phentermine and fenfluramine on extracellular dopamine and serotonin in rat nucleus accumbens: therapeutic implications. Synapse 2000; 36:102-13. [PMID: 10767057 DOI: 10.1002/(sici)1098-2396(200005)36:2<102::aid-syn3>3.0.co;2-#] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Combined administration of the amphetamine analogs phentermine and fenfluramine (PHEN/FEN) has been used in the treatment of obesity. While these medications are thought to modulate monoamine transmission, the precise neurochemical effects of the PHEN/FEN mixture have not been extensively studied. To assess the mechanism of PHEN/FEN action, in vivo microdialysis studies were performed in the nucleus accumbens of conscious freely moving rats. A series of amphetamine derivatives including phentermine, chlorphentermine, fenfluramine, and PHEN/FEN (1:1 ratio), were infused locally into the accumbens via reverse-dialysis (1, 10, 100 microM) or injected systemically (1 mg/kg, ip). Dialysate samples were assayed for dopamine (DA) and serotonin (5-HT) by high-performance liquid chromatography with electrochemical detection. When infused locally, phentermine preferentially increased extracellular DA, whereas fenfluramine selectively increased extracellular 5-HT. Local administration of chlorphentermine or the PHEN/FEN mixture caused parallel elevations of both transmitters. Analogous results were obtained when the drugs were injected systemically. Phentermine stimulated robust locomotor activity in mice, whereas chlorphentermine and fenfluramine did not. PHEN/FEN caused modest locomotor stimulation after a low dose, but had no effect at the highest dose. Accumulating evidence suggests that chronic drug and alcohol abuse is associated with deficits in both DA and 5-HT neuronal function. Thus, dual activation of DA and 5-HT neurotransmission with monoamine releasing agents may be an effective treatment strategy for substance use disorders, as well as for obesity. Synapse 36:102-113, 2000. Published 2000 Wiley-Liss, Inc.
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Affiliation(s)
- M H Baumann
- Clinical Psychopharmacology Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland 21224, USA
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Abstract
OBJECTIVE Body fatness is partly under hypothalamic control with effector limbs, which include the endocrine system and the autonomic nervous system (ANS). In previous studies we have shown, in both obese and never-obese subjects, that weight increase leads to increased sympathetic and decreased parasympathetic activity, whereas weight decrease leads to decreased sympathetic and increased parasympathetic activity. We now report on the involvement of such ANS mechanisms in the action of anti-obesity drugs, independent of change in weight. RESEARCH METHODS AND PROCEDURES Normal weight males (ages 22 to 38 years) were fed a solid food diet, carefully measured to maintain body weight, for at least 2 weeks, as inpatients at the Rockefeller University General Clinical Research Center. In a single-blind, placebo/drug/placebo design, eight subjects received dexfenfluramine, seven phentermine (PHE), and seven sibutramine (SIB). ANS measures of parasympathetic and sympathetic activity included: determination of amount of parasympathetic control (PC) and sympathetic control (SC) of heart period (interbeat interval), using sequential pharmacological blockade by intravenous administration of atropine and esmolol. These autonomic controls of heart period are used to estimate the overall level of parasympathetic and sympathetic activities. Norepinephrine, dopamine, and epinephrine levels in 24-hour urine collections were measured and also resting metabolic rate (RMR). RESULTS Sufficient food intake maintained constant body weight in all groups. PHE and SIB produced significant increases in SC but no change in PC or in RMR. In contrast, dexfenfluramine produced marked decreases in SC, PC, and RMR. For all three drugs, the effects on urine catecholamines directly paralleled changes in cardiac measures of SC. DISCUSSION ANS responses to PHE and SIB were anticipated. The large, and unanticipated, response to dexfenfluramine suggests further study to determine whether there could be any relation of these ANS changes to the adverse cardiovascular effects of treatment with dexfenfluramine.
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Affiliation(s)
- J Hirsch
- Laboratory of Human Behavior and Metabolism, The Rockefeller University, New York, New York 10021-6399, USA.
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Rada PV, Hoebel BG. Supraadditive effect of d-fenfluramine plus phentermine on extracellular acetylcholine in the nucleus accumbens: possible mechanism for inhibition of excessive feeding and drug abuse. Pharmacol Biochem Behav 2000; 65:369-73. [PMID: 10683475 DOI: 10.1016/s0091-3057(99)00219-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
The combination of d-fenfluramine plus phentermine (d-FEN/PHEN) provides a tool for exploring neural mechanisms that control food intake and drug abuse. Prior research suggests that dopamine (DA) in the nucleus accumbens can reinforce appetitive behavior and acetylcholine (ACh) inhibits it. When rats were given d-fenfluramine (5 mg/kg, IP) DA increased to 169% (p < 0.01), and ACh decreased slightly. Phentermine (5 mg/kg, IP) increased extracellular DA to 469% of baseline and ACh increased slightly to 124% (both p < 0.01). The d-FEN/PHEN combination, however, increased both DA and ACh with a supraadditive effect on ACh to 172%. One interpretation is that dFEN/PHEN increases DA like a meal or drug of abuse, while also increasing ACh to stop further approach behavior. This leaves the animal "satiated," as defined by reduced intake of food or drugs.
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Affiliation(s)
- P V Rada
- Princeton University, Department of Psychology, Princeton, NJ 08544, USA
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Rowland NE, Marshall M, Roth JD. Comparison of either norepinephrine-uptake inhibitors or phentermine combined with serotonergic agents on food intake in rats. Psychopharmacology (Berl) 2000; 149:77-83. [PMID: 10789886 DOI: 10.1007/s002139900336] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
RATIONALE We have shown previously that the anorectic effects of the catecholamine-releasing agent phentermine (PHEN) and the serotonin (5-HT)-releasing agent dexfenfluramine (DFEN) are greater than additive in rats. In the present study, we examined whether the norepinephrine-uptake inhibitors desmethylimipramine (DMI) and thionisoxetine (TNIX) have additive effects with either DFEN or with the 5-HT-uptake inhibitor fluoxetine (FLX). We also examined whether PHEN interacts with a postsynaptically acting 5-HT agonist. METHODS Undeprived rats were trained to eat a daily sweet-milk dessert and on test days were systemically administered single or combination drugs and the intakes recorded. RESULTS Both DMI and TNIX produced dose-related suppressions of food intake. However, by isobolographic analysis, they did not enhance the anorectic actions of either DFEN or FLX. In contrast, confirming and extending our previous work, PHEN had a greater potentiating effect on the anorectic actions of DFEN and FLX than TNIX. Further, the anorectic action of the 5-HT2c receptor agonist TFMPP was enhanced by PHEN. CONCLUSIONS These and other data are consistent with the idea that 5-HT agents may work "upstream" of critical catecholaminergic synapses in the production of anorexia, and explain the diminished efficacy of norepinephrine-uptake inhibitors relative to PHEN. The implications for clinically useful anorectic agents are discussed briefly.
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Affiliation(s)
- N E Rowland
- Department of Psychology, University of Florida, Gainesville 32611-2250, USA.
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Abstract
The drug combination of phentermine plus fenfluramine has been used clinically in both the treatment of obesity and alcoholism. The aim of the current study was to assess the interaction of the two drugs on consumption of both an alcohol-containing and a nonalcoholic diet. Furthermore, the efficacy of the drug combination on suppression of withdrawal seizures was determined. Animals were either maintained on a 6% alcohol-containing diet, free-fed an isocaloric control, or pair-fed the control diet. It was observed that, with regard to body weight growth curves, alcohol provides about 2.5 kcal/g. Both phentermine and fenfluramine caused a decrease in consumption 1 h after administration; however, during the next 23 h, 4 mg/kg phentermine significantly increased consumption of all diets. At doses of 1 and 2 mg/kg, fenfluramine selectively reduced consumption of the alcohol-containing diet as compared to the isocaloric diets. Lower doses of fenfluramine blocked the increases in consumption induced by phentermine. Furthermore, in animals fed the nonalcoholic diet, the drug combination of 2 mg/kg fenfluramine plus 8 mg/kg phentermine produced a 63-82% reduction in consumption, an effect not seen when either drug was administered alone. This greater than additive effect was also seen in the earlier time periods in animals pair-fed the control diet. Neurochemical analysis from these animals revealed that the alcohol-dependent animals displayed a significant reduction of DOPAC and 5-HIAA levels in the striatum, frontal cortex, and hypothalamus after a 9-h withdrawal period, further implicating the serotonergic and dopaminergic systems in mediation of withdrawal symptoms and alcohol craving. Finally, 8 mg/kg phentermine plus 8 mg/kg fenfluramine completely abolished alcohol withdrawal seizures, compared to a 78% rate in saline treated rats. In conclusion, the coadministration of phentermine plus fenfluramine produced a moderate reduction of alcohol consumption and was completely effective at reducing alcohol withdrawal seizures.
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Affiliation(s)
- A K Halladay
- Department of Psychology, Rutgers University, New Brunswick, NJ 08904, USA
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Stafford D, LeSage MG, Glowa JR. Effects of phentermine on responding maintained by progressive-ratio schedules of cocaine and food delivery in rhesus monkeys. Behav Pharmacol 1999; 10:775-84. [PMID: 10780293 DOI: 10.1097/00008877-199912000-00009] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Previous reports indicate that intravenous pretreatment with phentermine can decrease cocaine-maintained responding without affecting food-reinforced responding under fixed-ratio schedules. The present experiments were designed to explore the generality of this effect using progressive-ratio schedules of reinforcement and different routes of phentermine administration. Unit doses of cocaine and food-pellet magnitudes were identified that maintained similar breaking points, and the effects of acute exposure to phentermine were assessed. In Experiment 1, a 'conventional' (one-trial) progressive-ratio schedule was used, in which response requirements increased after each reinforcer delivery; in Experiment 2, a 'modified' (five-trial) progressive-ratio schedule was used, in which response requirements increased after every five reinforcer deliveries. In one group of monkeys, responding was maintained by food; in another, cocaine infusions maintained responding. Phentermine (0.1-5.6mg/kg, intramuscularly (i.m.)) dose-dependently decreased breakpoints on both progressive-ratio schedules. There were no differences in phentermine's effects on cocaine- and food-maintained behavior. In Experiment 3, intravenous administration of phentermine had largely similar effects. Taken together with results from previous reports, these data suggest that the effects of phentermine pretreatment are influenced by the behavioral procedure used to maintain responding and/or by the efficacy of the food and cocaine reinforcers.
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Affiliation(s)
- D Stafford
- Department of Pharmacology and Therapeutics, Louisiana State University Medical Center, Shreveport 71130-3932, USA
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Abstract
'Fen-phen' refers to the off-label combination of the appetite suppressants fenfluramine and phentermine. The rationale for the fen-phen combination was that the two drugs exerted independent actions on brain satiety mechanisms so that it was possible to use lower doses of each drug and yet retain a common action on suppressing appetite while minimizing adverse drug effects. The focus of the present review is to consider whether fenfluramine and phentermine exert actions that are additive in nature or whether these two drugs exhibit drug-drug synergism. The fen-phen combination results in synergism for the suppression of appetite and body weight, the reduction of brain serotonin levels, pulmonary vasoconstriction and valve disease. Fen-phen synergism may reflect changes in the pharmacokinetics of drug distribution, common actions on membrane ion currents, or interactions between neuronal release and reuptake mechanisms with MAO-mediated transmitter degradation. The synergism between fenfluramine and phentermine highlights the need to more completely understand the pharmacology and neurochemistry of appetite suppressants prior to use in combination pharmacotherapy for the treatment of obesity.
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Affiliation(s)
- P J Wellman
- Behavioral Neuroscience Program, Texas A&M University, College Station 77843-4235, USA.
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43
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Abstract
Fenfluramine + phentermine was a widely used combination for weight loss. Fenfluramine and phentermine are believed to act via serotonin and catecholamines, respectively. To what extent these drugs interact has not been well-established. We compared the anorectic efficacy of a range of doses of the combination (using dexfenfluramine instead of fenfluramine) relative to a range of doses of the individual drugs in 90 min sweetened milk intake tests in deprived and nondeprived rats. Results were plotted on isobolograms to determine whether the anorectic effects of the combination were either additive or synergistic. Collectively, the isobolographic analysis revealed that: (1) under acute conditions, dexfenfluramine and phentermine interact for the most part in a synergistic manner, and (2) with the exception of phentermine alone, deprivation state at time of testing did not alter the efficacy of the anorectics. These findings suggest that combined drug treatment for obesity is a theoretical approach that merits further investigation.
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Affiliation(s)
- J D Roth
- University of Florida, Gainesville 32611-2250, USA
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Abstract
Phentermine produces a spectrum of concentration-dependent biochemical effects. It interacts with NE transporters at 0.1 microM, DA transporters at about 1 microM, 5-HT transporters at 15 microM and MAO-A at about 100 microM. When administered at typical anorectic doses, phentermine primarily interacts with DA and NE transporters and does not produce biochemical or neurochemical effects which would occur if it were inhibiting MAO-A. Some other explanation other than MAO inhibition must be sought to explain how oral phentermine increases platelet 5-HT, since platelet MAO-B does not metabolize platelet 5-HT, and since amphetamine-type drugs are even weaker inhibitors of MAO-B than MAO-A. Clinical studies in humans have shown that amphetamine, which is a more potent inhibitor of MAO-A than phentermine, does not inhibit MAO-A at therapeutic doses. Neither phentermine alone, fluoxetine alone or their combined use have been associated with cardiac valvulopathy, and clinical experience has shown their combined use to be free of significant adverse effects. Viewed collectively, there appears to be no data to support the hypothesis that phentermine inhibits MAO at typical therapeutic doses.
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Reeve HL, Nelson DP, Archer SL, Weir EK. Effects of fluoxetine, phentermine, and venlafaxine on pulmonary arterial pressure and electrophysiology. Am J Physiol 1999; 276:L213-9. [PMID: 9950882 DOI: 10.1152/ajplung.1999.276.2.l213] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The anorexic agents dexfenfluramine and fenfluramine plus phentermine have been associated with outbreaks of pulmonary hypertension. The fenfluramines release serotonin and reduce serotonin reuptake in neurons. They also inhibit potassium current (IK), causing membrane potential depolarization in pulmonary arterial smooth muscle cells. The recent withdrawal of the fenfluramines has led to the use of fluoxetine and phentermine as an alternative anorexic combination. Because fluoxetine and venlafaxine reduce serotonin reuptake, we compared the effects of these agents with those of phentermine and dexfenfluramine on pulmonary arterial pressure, IK, and membrane potential. Fluoxetine, venlafaxine, and phentermine caused minimal increases in pulmonary arterial pressure at concentrations < 100 microM but did cause a dose-dependent inhibition of IK. The order of potency for inhibition of IK at +50 mV was fluoxetine > dexfenfluramine = venlafaxine > phentermine. Despite the inhibitory effect on IK at more positive membrane potentials, fluoxetine, venlafaxine, and phentermine, in contrast to dexfenfluramine, had minimal effects on the cell resting membrane potential (all at a concentration of 100 microM). However, application of 100 microM fluoxetine to cells that had been depolarized to -30 mV by current injection elicited a further depolarization of >18 mV. These results suggest that fluoxetine, venlafaxine, and phentermine do not inhibit IK at the resting membrane potential. Consequently, they may present less risk of inducing pulmonary hypertension than the fenfluramines, at least by mechanisms involving membrane depolarization.
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Affiliation(s)
- H L Reeve
- Department of Physiology, University of Alberta, Edmonton, Canada T6G 2R7
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Wojnicki FH, Rothman RB, Rice KC, Glowa JR. Effects of phentermine on responding maintained under multiple fixed-ratio schedules of food and cocaine presentation in the rhesus monkey. J Pharmacol Exp Ther 1999; 288:550-60. [PMID: 9918558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023] Open
Abstract
Drugs that decrease drug-maintained responding at doses that do not decrease other behaviors in animals may be suitable candidates for development as medications to treat drug abuse in humans. The present study examined whether this effect could be obtained with phentermine, a drug that has been reported to decrease cocaine intake in humans. Rhesus monkeys were trained under multiple fixed-ratio 30-response schedules of food and i.v. cocaine delivery. Phentermine was always given as a slow, i.v. infusion. Acute treatment with phentermine (0.3-10 mg/kg) decreased cocaine-maintained responding at doses that did not decrease, or decreased less, food-maintained responding for each of three unit doses of cocaine (10-100 microg/kg/injection). Subacute treatment with phentermine (3 or 5.6 mg/kg, daily) also decreased cocaine-maintained responding more than food-maintained responding. After subacute treatment was terminated, rates of cocaine-maintained responding generally recovered to levels comparable to those seen during untreated control sessions. Phentermine (0.3-3 mg/kg) did not generally increase responding associated with a very low (1 microg/kg/injection) unit dose of cocaine, suggesting that the decrease in cocaine-maintained responding at higher unit doses was not the result of a leftward shift in the cocaine unit dose-effect function. Phentermine (0.1-3 mg/kg) decreased responding maintained by 1-[2-[bis(4-fluorophenyl) methoxy]ethyl]-4-[3-phenylpropyl] piperazine (GBR 12909) (30 microg/kg/injection) at doses similar to those that decreased food-maintained responding. These results show that phentermine is effective in decreasing cocaine self-administration and suggest that it may be an effective medication for cocaine abuse.
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Affiliation(s)
- F H Wojnicki
- Laboratory of Medicinal Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA
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Munzar P, Baumann MH, Shoaib M, Goldberg SR. Effects of dopamine and serotonin-releasing agents on methamphetamine discrimination and self-administration in rats. Psychopharmacology (Berl) 1999; 141:287-96. [PMID: 10027510 DOI: 10.1007/s002130050836] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
To analyze the involvement of dopamine (DA) and serotonin (5-HT) release in the stimulus properties of methamphetamine, two amphetamine analogs that selectively release either brain DA (phentermine) or 5-HT (fenfluramine) were tested for their ability to substitute for methamphetamine in rats discriminating methamphetamine (1.0 mg/kg) from saline. They were subsequently tested for their ability to alter IV methamphetamine (0.06 mg/kg per injection) self-administration in the same species when given as a pretreatment. The DA releaser phentermine, like methamphetamine itself, decreased methamphetamine self-administration (to 70% of baseline responding), but only at a dose of 3.0 mg/kg that fully generalized to the methamphetamine stimulus in the discrimination study. The 5-HT releaser fenfluramine attenuated methamphetamine self-administration to a much larger extent than phentermine (to 37% of baseline responding) at a dose of 1.8 mg/kg that did not generalize to methamphetamine and did not decrease rate of responding in the discrimination study. Tolerance developed to the inhibitory effect of 1.8 mg/kg fenfluramine on methamphetamine self-administration when it was given repeatedly over four consecutive daily sessions. The fenfluramine-induced decrease in methamphetamine self-administration was also attenuated when it was given together with the small 1.0 mg/kg dose of phentermine. These results suggest that DA release plays a dominant role in the discriminative stimulus effects of methamphetamine. However, stimulation of 5-HT release can strongly modify methamphetamine self-administration.
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Affiliation(s)
- P Munzar
- Preclinical Pharmacology Laboratory, Addiction Research Center, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
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Balcioglu A, Wurtman RJ. Effects of fenfluramine and phentermine (fen-phen) on dopamine and serotonin release in rat striatum: in vivo microdialysis study in conscious animals. Brain Res 1998; 813:67-72. [PMID: 9824670 DOI: 10.1016/s0006-8993(98)01003-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We measured the effects of acute or chronic administration of fenfluramine and phentermine, alone or in combination, on brain dopamine and serotonin release into striatal dialysates of freely moving rats. Samples collected every 30 min were assayed in a single run by high-pressure liquid chromatography. Acute or chronic administration of fenfluramine (1 mg/kg, i.p.) did not significantly change dopamine concentrations in rat striatal dialysates, but increased those of serotonin by 182% (acute) and 124% (chronic). Phentermine (2 mg/kg, i.p.), on the other hand, significantly increased dopamine concentrations by 52% (acute) and 80% (chronic) without affecting those of serotonin. Administration of the drugs in combination (fenfluramine 1 mg/kg and phentermine 2 mg/kg) amplified the effects of each, increasing striatal dopamine concentrations by 209% (acute) and serotonin concentrations by 330% (acute) and 299% (chronic).
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Affiliation(s)
- A Balcioglu
- Massachusetts Institute of Technology, Department of Brain and Cognitive Sciences, E25-604, Cambridge, MA 02139, USA
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