Combination therapy with naltrexone and bupropion for obesity

Efficacy of Oral Medication in Weight Loss Management: A Systematic Review and Network Meta-Analysis

PURPOSE

This systematic review was conducted to determine which type of oral medication for obesity provides the best weight loss effect.

METHODS

This study adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guideline. For this systematic review, we used 3 databases for journal searches: PubMed, ScienceDirect, and Scopus. This study only included randomized controlled trials or open-label clinical trials. There was no year limit used in the journal search for this systematic review.

FINDINGS

Eighteen randomized controlled trials, with a total population of 12,259 patients, were included. Of 18 studies, 15 were used for network meta-analysis. Based on the results of the network meta-analysis, weight loss was found in phentermine/topiramate (mean difference [MD], -3.28; 95% CI, -4.47 to -2.09), semaglutide (MD, -2.92; 95% CI, -4.38 to -1.46), phentermine (MD, -2.31; 95% CI, -3.82 to -0.81), naltrexone/bupropion (MD, -1.68; 95% CI, -2.87 to -0.49), topiramate (MD, -1.67; 95% CI, -2.86 to -0.48), and orlistat (MD, -1.44; 95% CI, -2.32 to -0.55). There were no significant differences among the groups. However, compared with placebo, all oral obesity therapies provide better benefits in weight loss (MD, -2.12; 95% CI, -2.64 to -1.59; P ≤ 0.00001).

IMPLICATIONS

Oral antiobesity drugs provide better weight loss than placebo. However, some side effects can be incurred by utilizing the drug for weight loss, especially related to the gastrointestinal system. Nonetheless, in clinical settings, consideration should be given to particular patients to reduce risk of side effects.

Differential effects of liraglutide naltrexone/bupropion, and caloric restriction on metabolic parameters and beta-cell regeneration in type 2 diabetic rat model: role of beta arrestin 1

Traditional antidiabetic treatments often carry the risk of beta-cell exhaustion, highlighting the need for therapies that promote beta-cell regeneration. This study investigates the comparative effects of Liraglutide, naltrexone/bupropion (NTX + BUP), and caloric restriction on metabolic control and beta-cell regeneration in a rat model of obese type 2 diabetes. Fifty male albino rats were randomized into five groups: normal control, diabetic control, diabetic + caloric restriction (50%), diabetic + NTX + BUP (4 mg/45 mg /kg/day orally), and diabetic + liraglutide (0.3 mg/kg/day, S.C). Body weight, BMI, serum glucose, insulin, lipid profile, atherogenic indices, beta-arrestin-1 levels, pancreatic histopathology, and immunohistochemical staining for insulin and Ki67 were assessed. All interventions significantly improved body weight, BMI, glycemic control, lipid profiles (except HDL), and atherogenic indices compared to the diabetic control group. NTX + BUP and caloric restriction resulted in greater weight loss compared to liraglutide. Of note, liraglutide significantly decreased β-arrestin-1 levels compared to both NTX + BUP and caloric restriction. Furthermore, liraglutide and caloric restriction significantly increased anti-insulin antibodies and Ki67 indicating beta-cell regeneration, while NTX + BUP showed insignificant effects. Thus we can conclude that, while NTX + BUP demonstrates efficacy in improving metabolic parameters in obese type 2 diabetic rats, it shows limitations in promoting beta-cell regeneration compared to liraglutide and caloric restriction.

Update on Pediatric Anti-obesity Medications-Current Landscape and Approach to Prescribing

PURPOSE OF REVIEW

To review the current medical therapies available for treatment of obesity in children and adolescents less than 18 years old in the United States and outline the approach to their use.

RECENT FINDINGS

Obesity is a chronic disease with increasing prevalence in children and adolescents in the United States. Over the past few years, more FDA-approved medical treatments for obesity, such as GLP-1 receptor agonists, have emerged for patients less than 18 years old. Furthermore, there are medications with weight loss effects that can be used off-label for obesity in pediatric patients. However, access to many of these medications is limited due to age restrictions, insurance coverage, and cost. Medical options are improving to provide treatment for obesity in pediatric populations. FDA and off-label medications should be considered when appropriate to treat children and adolescents with obesity. However, further studies are needed to evaluate the efficacy and long-term safety of FDA-approved and off-label medications for obesity treatment in pediatric patients.

Advancements in the management of obesity: a review of current evidence and emerging therapies

INTRODUCTION

Obesity is the modern world's current epidemic, with substantial health and economic impact. This study aimed to provide a narrative overview of the past, currently available, and future treatment options that offer therapeutic and preventive advantages for obesity management.

AREAS COVERED

Historically, rimonabant, and lorcaserin, were approved and used for managing non-syndromic obesity. Currently, orlistat, naltrexone/bupropion, glucagon-like peptide-1 receptor agonist (GLP-1 RA), and a few promising therapeutic agents are under investigation, including retatrutide, cagrilintide and orforglipron, which show promising weight reduction effects. We have developed a search string of the Medical Subject Headings (MeSH), including the terms GLP-1 RAs, obesity, and weight loss. This string was then used to perform a systematic literature search in the database including PubMed, EMBASE, MEDLINE, and Scopus up to January 31st, 2024.

EXPERT OPINION

Managing obesity often requires medical interventions, particularly in cases of severe obesity or obesity-related comorbidities. Thus, it is important to approach obesity management holistically, considering individual needs and circumstances. In our opinion, consulting with healthcare professionals is crucial to developing a personalized plan that addresses both weight loss and overall health improvement.

Changes in lipid profile and glucose metabolism following administration of bupropion alone or in combination with naltrexone: A systematic review and meta-regression analysis

BACKGROUND

Considering the conflicting effects of bupropion on parameters related to metabolic syndrome including glucose metabolism and lipid profile, in this meta-analysis study, we investigated the effects of this drug alone or in combination with naltrexone on glucose metabolism and lipid profile.

METHODS

Scopus, PubMed/Medline, Web of Science and Embase databases were searched using standard keywords to identify all controlled trials investigating effects of bupropion alone and combined with naltrexone on the glucose and lipid profile. Pooled weighted mean difference and 95% confidence intervals were achieved by random-effects model.

RESULTS

Twelve studies with 5152 participants' were included in this article. The pooled findings showed that bupropion alone or in combination with naltrexone would significantly reduce glucose (weighted mean difference (WMD): -2.25 mg/dL, 95% confidence interval (CI): -4.10, -0.40), insulin (WMD: -4.06 μU/mL, 95% CI: -6.09, -2.03), homeostatic model assessment for insulin resistance (HOMA-IR) (WMD: -0.58, 95% CI: -0.98, -0.19), triglyceride (TG) (WMD: -11.78 mg/dL, 95% CI: -14.48 to -9.08) and increase high-density lipoprotein (HDL) (WMD: 2.68 mg/dL, 95% CI: 2.13 to 3.24). A Greater reduction in glucose levels was observed with duration >26 weeks. Dose of bupropion intake ≤360 mg and intervention for more than 26 weeks decreased insulin level significantly. With regard to lipid profile, reduction of triglycerides is more significant with dose of bupropion greater than 360 mg and a shorter intervention length equal to 26 weeks.

CONCLUSIONS

The addition of combination therapies such as bupropion and naltrexone to lifestyle modification can significantly improve glucose metabolism and some lipid parameters.

The effects of bupropion alone and combined with naltrexone on blood pressure and CRP concentration: A systematic review and meta-regression analysis of randomized controlled trials

BACKGROUND

Considering the conflicting effects of bupropion on parameters related to cardiovascular system including blood pressure and inflammation, in this meta-analysis study, we investigated the effects of this drug alone or in combination with naltrexone on systolic (SBP) and diastolic blood pressure (DBP) and C-reactive protein (CRP).

METHODS

Scopus, PubMed/Medline, Web of Science and Embase databases were searched using standard keywords to identify all controlled trials investigating effects of bupropion alone and combined with naltrexone on the BP and CRP. Pooled weighted mean difference and 95% confidence intervals (CIs) were achieved by random-effects model analysis for the best estimation of outcomes.

RESULTS

The pooled findings showed that that bupropion alone or in combination with naltrexone would significantly increase SBP (weighted mean difference (WMD): 1.34 mmHg, 95% CI: 0.38-2.29) and DBP (WMD: 0.93 mmHg, 95% CI 0.88-0.99) as well as decrease CRP (WMD: -0.89 mg/L, 95% CI -1.09 to -0.70). The findings of the subgroup also show the greater effect of bupropion on blood pressure (SBP and DBP) increase in a dose greater than 360 mg and a duration of intervention less equal to 26 weeks. In addition, the subgroup analysis showed that changes in SBP after receiving bupropion together with naltrexone were more compared to bupropion alone.

CONCLUSIONS

The addition of combination therapies such as bupropion and naltrexone can significantly improve CRP levels. However, its effect on blood pressure requires proper management of this drug.

Naltrexone plus bupropion combination medication maintenance treatment for binge-eating disorder following successful acute treatments: randomized double-blind placebo-controlled trial

BACKGROUND

Certain treatments have demonstrated acute efficacy for binge-eating disorder (BED) but there is a dearth of controlled research examining pharmacotherapies as maintenance treatments for responders to initial interventions. This gap in the literature is particularly critical for pharmacotherapy for BED which is associated with relapse following discontinuation. The current study tested the efficacy of naltrexone/bupropion maintenance treatment amongst responders to acute treatments for BED.

METHODS

Prospective randomized double-blind placebo-controlled single-site trial, conducted August 2017-December 2021, tested naltrexone/bupropion as maintenance treatment for responders to acute treatments with naltrexone/bupropion and/or behavioral weight-loss therapy for BED with comorbid obesity. Sixty-six patients (84.8% women, mean age 46.9, mean BMI 34.9 kg/m2) who responded to acute treatments were re-randomized to placebo (N = 34) or naltrexone/bupropion (N = 32) for 16 weeks; 86.3% completed posttreatment assessments. Mixed models and generalized estimating equations comparing maintenance treatments (naltrexone/bupropion v. placebo) included main and interactive effects of acute treatments.

RESULTS

Intention-to-treat binge-eating remission rates following maintenance treatments were 50.0% (N = 17/34) for placebo and 68.8% (N = 22/32) for naltrexone/bupropion. Placebo following response to acute treatment with naltrexone/bupropion was associated with significantly decreased probability of binge-eating remission, increased binge-eating frequency, and no weight loss. Naltrexone/bupropion following response to acute treatment with naltrexone/bupropion was associated with good maintenance of binge-eating remission, low binge-eating frequency, and significant additional weight loss.

CONCLUSIONS

Adult patients with BED with co-occurring obesity who have good responses to acute treatment with naltrexone/bupropion should be offered maintenance treatment with naltrexone/bupropion.

Naltrexone/bupropion for binge-eating disorder: A randomized, double-blind, placebo-controlled trial

OBJECTIVE

Binge-eating disorder (BED) is a prevalent psychiatric disorder associated with obesity. Few evidence-based treatments exist for BED, particularly pharmacological options. This study tested the efficacy of naltrexone/bupropion for BED.

METHODS

A randomized, double-blind, placebo-controlled, 12-week trial tested naltrexone/bupropion for BED with and without obesity. Eighty-nine patients (70.8% women, 69.7% White, mean age 45.7 y, mean BMI 35.1 kg/m2 , 77.5% with BMI ≥ 30 kg/m2 ) were randomized to placebo (n = 46) or naltrexone/bupropion (n = 43), with randomization stratified by obesity status and gender; 92.1% completed post-treatment assessments.

RESULTS

Mixed models of binge-eating frequency revealed significant reductions that did not differ significantly between naltrexone/bupropion and placebo. Logistic regression of binge-eating remission rates revealed that naltrexone/bupropion and placebo did not differ significantly. Obesity status did not predict, or moderate, binge-eating outcomes considered either continuously or categorically. Mixed models revealed that naltrexone/bupropion was associated with significantly greater percentage weight loss than placebo. Logistic regression revealed that naltrexone/bupropion had significantly higher rates of attaining ≥5% weight loss than placebo (27.9% vs. 6.5%). Obesity status did not predict or moderate weight-loss outcomes.

CONCLUSIONS

Naltrexone/bupropion did not demonstrate effectiveness for reducing binge eating relative to placebo but showed effectiveness for weight reduction in patients with BED. Obesity status did not predict or moderate medication outcomes.

Cognitive-behavioral therapy for binge-eating disorder for non-responders to initial acute treatments: Randomized controlled trial

OBJECTIVE

Certain treatments have demonstrated acute efficacy for binge-eating disorder (BED) but many patients who receive "evidence-based" interventions do not derive sufficient benefit. Given the dearth of controlled research examining treatments for patients who fail to respond to initial interventions, this study tested the efficacy of cognitive-behavioral therapy (CBT) for patients with BED who do not respond to initial acute treatments.

METHODS

Prospective randomized double-blind placebo-controlled single-site trial, conducted August 2017-December 2021, tested 16-weeks of therapist-led CBT for non-responders to initial treatment (naltrexone/bupropion and/or behavioral therapy) for BED with obesity. Thirty-one patients (mean age 46.3 years, 77.4% women, 80.6% White, mean BMI 38.99 kg/m2 ) who were non-responders to initial acute treatments were randomized to CBT (N = 18) or no-CBT (N = 13), in addition to continuing double-blinded pharmacotherapy. Independent assessments were performed at baseline, throughout treatment, and posttreatment; 83.9% completed posttreatment assessments.

RESULTS

Intention-to-treat remission rates were significantly higher for CBT (61.1%; N = 11/18) than no-CBT (7.7%; N = 1/13). Mixed models of binge-eating frequency (assessed using complementary methods) converged revealing a significant interaction between CBT and time and a significant main effect of CBT. Binge-eating frequency decreased significantly with CBT but did not change significantly with no-CBT. Since only four patients received behavioral treatment during the acute treatments, we performed "sensitivity-type" analyses restricted to the 27 patients who received pharmacotherapy during the acute treatment and found the same pattern of findings for CBT versus no-CBT.

CONCLUSIONS

Adult patients with BED who fail to respond to initial pharmacological treatments should be offered CBT.

PUBLIC SIGNIFICANCE

Even with leading evidence-based treatments for binge-eating disorder, many patients do not derive sufficient benefit. Almost no controlled research has examined treatments for patients who fail to respond to initial interventions. This study found that that cognitive-behavioral therapy was effective for patients with binge-eating disorder who did not respond to initial interventions, with 61% achieving abstinence.

Naltrexone-Bupropion and Behavior Therapy, Alone and Combined, for Binge-Eating Disorder: Randomized Double-Blind Placebo-Controlled Trial

OBJECTIVE

Binge-eating disorder, the most prevalent eating disorder, is a serious public health problem associated with obesity, psychiatric and medical comorbidities, and functional impairments. Binge-eating disorder remains underrecognized and infrequently treated, and few evidence-based treatments exist. The authors tested the effectiveness of naltrexone-bupropion and behavioral weight loss therapy (BWL), alone and combined, for binge-eating disorder comorbid with obesity.

METHODS

In a randomized double-blind placebo-controlled trial conducted from February 2017 to February 2021, using a 2×2 balanced factorial design, 136 patients with binge-eating disorder (81.6% women; mean age, 46.5 years; mean BMI, 37.1) were randomized to one of four 16-week treatments: placebo (N=34), naltrexone-bupropion (N=32), BWL+placebo (N=35), or BWL+naltrexone-bupropion (N=35). Overall, 81.7% of participants completed independent posttreatment assessments.

RESULTS

Intention-to-treat binge-eating remission rates were 17.7% in the placebo group, 31.3% in the naltrexone-bupropion group, 37.1% in the BWL+placebo group, and 57.1% in the BWL+naltrexone-bupropion group. Logistic regression of binge-eating remission revealed that BWL was significantly superior to no BWL, and that naltrexone-bupropion was significantly superior to placebo, but there was no significant interaction between BWL and medication. Mixed models of complementary measures of binge-eating frequency also indicated that BWL was significantly superior to no BWL. The rates of participants attaining 5% weight loss were 11.8% in the placebo group, 18.8% in the naltrexone-bupropion group, 31.4% in the BWL+placebo group, and 38.2% in the BWL+naltrexone-bupropion group. Logistic regression of 5% weight loss and mixed models of percent weight loss both revealed that BWL was significantly superior to no BWL. Mixed models revealed significantly greater improvements for BWL than no BWL on secondary measures (eating disorder psychopathology, depression, eating behaviors, and cholesterol and HbA1c levels).

CONCLUSIONS

BWL and naltrexone-bupropion were associated with significant improvements in binge-eating disorder, with a consistent pattern of BWL being superior to no BWL.

Weight-centric treatment of depression and chronic pain

BACKGROUND

Depression and chronic pain are two major chronic non-communicable diseases (CNCD). Considering the bidirectional relationship between obesity and CNCD, it is of the utmost importance to understand the effect of medications utilized to treat these diseases on body weight.

METHODS

This is a clinical review on the effect of medications for depression and chronic pain on body weight. We searched PubMed, Scopus, MEDLINE, and Google Scholar databases for studies on the topic from January 1, 1950 to April 1, 2022 in English language. Additionally, we present expert opinions in the fields of obesity, depression and chronic pain, providing a weight-centric approach to treat depression and chronic pain.

RESULTS

Several antidepressant and chronic pain medications are associated with weight gain. Selective serotonin reuptake inhibitors, serotonin and norepinephrine reuptake inhibitors, tricyclic antidepressants, monoamine oxidases, mirtazapine and trazodone are common antidepressants that can increase body weight while bupropion is significantly associated with weight loss. Gabapentin and pregabalin are common chronic pain medications that are linked to weight gain. On the other hand, topiramate is associated with significant weight loss. Obesity, depression and chronic pain experts recommend avoiding medications that can increase body weight if another effective alternative is available.

CONCLUSION

By shifting prescribing practices toward a weight-conscious approach (i.e., switching from weight gain medications to weight loss/neutral), it is possible to mitigate the incidence of drug-induced weight gain.

A narrative review of anti-obesity medications for obese patients with osteoarthritis

INTRODUCTION

: The prevalence of both obesity and osteoarthritis (OA) are increasing worldwide (twindemic), and the association between the two chronic diseases is also well-established.

AREAS COVERED

: In this narrative review, we will briefly describe the double burdens of both diseases, the impact of weight loss or gain on OA incidence and structural progression and discuss the biomechanical and anti-inflammatory mechanisms mediating these effects. FDA-approved anti-obesity drugs are summarized in terms of their clinical efficacy and safety profile, and the completed or ongoing phase 2/3 clinical trials of such drugs in OA patients with obesity are examined.

EXPERT OPINION

: We will discuss the perspectives related to principles of prescription of anti-obesity drugs, the potential role of phenotype-guided approach, time to drug effects in clinical trials, sustainability of weight loss based on the real-world studies, the importance of concomitant therapies such as dieting and exercises, and the role of weight loss on non-weight bearing OA joints. Although obesity is the major risk factor for OA pathogenesis and progression, and there are a variety of anti-obesity medications on the market, research on the use of these disease-modifying drugs in OA (DMOAD) is still sparse..

How and when to treat the most common adverse effects of antipsychotics: Expert review from research to clinical practice

OBJECTIVE

As most treatment guidelines for antipsychotics focus on clinical efficacy, we will instead focus on adverse effects and how to manage them. In this review, we aim to provide an up-to-date clinical resource for providers who prescribe antipsychotics and have included here "what's new" and "what to do" for numerous antipsychotic-induced adverse effects.

METHODS

A review was performed of relevant literature, studies, randomized clinical trials, and systematic reviews. This information was combined with the clinical experience of the authors to formulate a practical guide for treating adverse effects of antipsychotics with an emphasis on metabolic and movement disorder adverse effects and brief mention of some others (sedation and sexual dysfunction).

CONCLUSIONS

Antipsychotics are an integral part of psychiatric care and are often prescribed lifelong. When choosing an antipsychotic, special consideration must be given to adverse effects which have an undeniable impact on quality of life and can often be the deciding factor in patients' medication compliance. While patients may respond well to one specific medication, they may still experience adverse effects that lead them to discontinue it or switch to a more tolerable but less effective option. However, strategies do exist for managing and treating adverse effects, especially metabolic and movement adverse effects, allowing better personalization of antipsychotic choice.

The Neurobiology of Binge-eating Disorder Compared with Obesity: Implications for Differential Therapeutics

PURPOSE

Emerging work indicates divergence in the neurobiologies of binge-eating disorder (BED) and obesity despite their frequent co-occurrence. This review highlights specific distinguishing aspects of BED, including elevated impulsivity and compulsivity possibly involving the mesocorticolimbic dopamine system, and discusses implications for differential therapeutics for BED.

METHODS

This narrative review describes epidemiologic, clinical, genetic, and preclinical differences between BED and obesity. Subsequently, this review discusses human neuroimaging work reporting differences in executive functioning, reward processing, and emotion reactivity in BED compared with obesity. Finally, on the basis of the neurobiology of BED, this review identifies existing and new therapeutic agents that may be most promising given their specific targets based on putative mechanisms of action relevant specifically to BED.

FINDINGS

BED is characterized by elevated impulsivity and compulsivity compared with obesity, which is reflected in divergent neurobiological characteristics and effective pharmacotherapies. Therapeutic agents that influence both reward and executive function systems may be especially effective for BED.

IMPLICATIONS

Greater attention to impulsivity/compulsivity-related, reward-related, and emotion reactivity-related processes may enhance conceptualization and treatment approaches for patients with BED. Consideration of these distinguishing characteristics and processes could have implications for more targeted pharmacologic treatment research and interventions.

Naltrexone + Bupropion Combination for the Treatment of Binge-eating Disorder with Obesity: A Randomized, Controlled Pilot Study

PURPOSE

Binge-eating disorder (BED), the most prevalent eating disorder, is associated strongly with obesity and functional impairments. Few evidence-based treatments for BED exist; a pharmacotherapy effective in reducing both binge eating and weight needs to be identified. This placebo-controlled double-blind pilot RCT evaluated the acute effects of naltrexone + bupropion (NB) on BED with obesity and examined the longer-term effects through 6-month follow-up after the discontinuation of medication.

METHODS

Twenty-two adult patients with BED were randomized to receive 12 weeks of double-blind treatment with fixed-dose NB (naltrexone + bupropion XL 50/300 mg) or placebo. Independent (blinded) researcher-clinicians evaluated patients at major outcome time points (baseline, posttreatment, and 6-month follow-up after the treatment period); patients were also evaluated for the tracking of course/tolerability throughout treatments and at 3-month follow-up. Primary outcomes were changes from baseline in binge-eating frequency and percentage weight. Secondary outcomes were changes in eating-disorder psychopathology and depression.

FINDINGS

A total of 22 patients were enrolled (86.4% women; mean age, 50.4 years), with 77.3% of patients completing treatments; completion rates (NB, 83.3%; placebo, 70.0%) and adverse events did not differ significantly between NB and placebo. Analyses revealed significant reductions from baseline in binge-eating, eating-disorder psychopathology, depression, and weight during treatment, but these changes with NB did not differ significantly from those with placebo. The percentage of patients who attained 3% weight loss was significantly greater with NB than with placebo (45.5% vs 0%); weight-loss and binge-eating reductions were significantly correlated in the group that received NB. At 6-month follow-up, outcomes remained improved relative to baseline, with no significant differences between NB and placebo.

IMPLICATIONS

The findings from this pilot RCT suggest that NB was well-tolerated in these patients with BED and comorbid obesity. Most outcomes were not statistically different between NB and placebo. A larger-scale, adequately powered RCT is needed for determining the efficacy of NB in the treatment of BED. ClinicalTrials.gov identifier: NCT02317744.

Current Options for the Pharmacotherapy of Obesity

650 millions of adults are obese worldwide - in the US alone, forty percent of the adults are obese. Although the obesity pandemic is constantly expanding at very high costs for health care systems, the currently available options of pharmacotherapy for obesity are rather limited. Despite intensive research efforts, the vast majority of the anti-obesity drugs developed up to now have a rather limited efficacy and/or safety profile. In the last fifty years, various drugs reached advanced states of clinical development but were either never marketed or were initially approved but withdrawn later due to safety issues. However, the understanding of the pathophysiology of obesity has been steadily improving and new, promising drugs targeting various selective obesityassociated and energy-homeostasis-related pathways are now available. When lifestyle changes alone fail to combat, then additional pharmacotherapy with an acceptable efficacy and safety profile could provide a useful therapeutic option.

Pharmacotherapy for the treatment of obesity

The recognition of the complex counter-regulatory hormonal, metabolic and neurochemical mechanisms that promote weight regain following weight loss and the conceptualisation of obesity as a chronic disease requiring long-term management has led to increasing focus on the role of adjunctive therapies for obesity, particularly pharmacotherapy. Currently available pharmacotherapy achieves a weight loss intermediate between that commonly attained by lifestyle intervention and bariatric surgery, however its accessibility, compared to bariatric surgery increases its appeal. Despite the poor history of obesity pharmacotherapy, novel agents that are in development appear to have several advantages over predecessors. They are generally more selective in their mechanism of action, thereby potentially minimising adverse sequelae and improving the risk-benefit ratio of pharmacotherapy. Another approach has been to use combined pharmacotherapy to better counteract the multiple counter-regulatory neuroendocrine mechanisms which promote weight regain, as well as allowing lower constituent doses of the combined monotherapy agents, which improves the safety and tolerability of these agents that are usually required long-term for chronic weight maintenance. This review will provide an overview of past, present and future pharmacotherapy for obesity. The efficacy and safety profile of currently available pharmacotherapy will be discussed in the setting of stringent regulatory review processes now in place given the fraught history of pharmacological interventions for obesity. Potential novel therapies that seek to better target the multiple complex counter-regulatory mechanisms promoting weight regain while improving the efficacy/safety profile, will also be examined.

Opposing neural effects of naltrexone on food reward and aversion: implications for the treatment of obesity

RATIONALE

Opioid antagonism reduces the consumption of palatable foods in humans but the neural substrates implicated in these effects are less well understood.

OBJECTIVES

The aim of the present study was to examine the effects of the opioid antagonist, naltrexone, on neural response to rewarding and aversive sight and taste stimuli.

METHODS

We used functional magnetic resonance imaging (fMRI) to examine the neural responses to the sight and taste of pleasant (chocolate) and aversive (mouldy strawberry) stimuli in 20 healthy volunteers who received a single oral dose of naltrexone (50 mg) and placebo in a double-blind, repeated-measures cross-over, design.

RESULTS

Relative to placebo, naltrexone decreased reward activation to chocolate in the dorsal anterior cingulate cortex and caudate, and increased aversive-related activation to unpleasant strawberry in the amygdala and anterior insula.

CONCLUSIONS

These findings suggest that modulation of key brain areas involved in reward processing, cognitive control and habit formation such as the dorsal anterior cingulate cortex (dACC) and caudate might underlie reduction in food intake with opioid antagonism. Furthermore we show for the first time that naltrexone can increase activations related to aversive food stimuli. These results support further investigation of opioid treatments in obesity.

Naltrexone sustained-release/bupropion sustained-release for the management of obesity: review of the data to date

Obesity is an emerging disease worldwide. Changes in living habits, especially with increased consumption of high-calorie foods and decreased levels of physical activity, lead to an energy imbalance that brings weight gain. Overweight and obesity are major risk factors for several chronic diseases (including cardiovascular diseases, diabetes, and cancer), reduce quality of life, and are associated with higher mortality. For all these reasons, it is of the utmost importance that the trend be reversed and obese people enabled to lose weight. It is known that eating a healthy diet and exercising regularly can help prevent obesity, but data show that in many cases these steps are not enough. This is the reason why, over the last few decades, several antiobesity drugs have been developed. However, the disappointing results demonstrated for the vast majority of them have not discouraged the pharmaceutical industry from continuing to look for an effective drug or combination of drugs. The systematic review presented here focuses on naltrexone sustained-release/bupropion sustained-release combination (Contrave^®). We conclude from the current published reports that its effectiveness in the treatment of obesity can be estimated as a placebo-subtracted weight loss of around 4.5%. This weight reduction is moderate but similar to other antiobesity drugs. The safety profile of this combination is acceptable, despite additional data regarding cardiovascular disease being needed.

Past and future corollaries of theories on causes of metabolic syndrome and obesity related co-morbidities part 2: a composite unifying theory review of human-specific co-adaptations to brain energy consumption

Metabolic syndrome (MetS) predicts type II diabetes mellitus (TIIDM), cardiovascular disease (CVD) and cancer, and their rates have escalated over the last few decades. Obesity related co-morbidities also overlap the concept of the metabolic syndrome (MetS). However, understanding of the syndrome's underlying causes may have been misapprehended. The current paper follows on from a theory review by McGill, A-T in Archives of Public Health, 72: 30. This accompanying paper utilises research on human evolution and new biochemistry to theorise on why MetS and obesity arise and how they affect the population. The basis of this composite unifying theory is that the proportionately large, energy-demanding human brain may have driven co-adaptive mechanisms to provide, or conserve, energy for the brain. A 'dual system' is proposed. 1) The enlarged, complex cortico-limbic-striatal system increases dietary energy by developing strong neural self-reward/motivation pathways for the acquisition of energy dense food, and (2) the nuclear factor-erythroid 2-related factor 2 (NRF2) cellular protection system amplifies antioxidant, antitoxicant and repair activity by employing plant chemicals. In humans who consume a nutritious diet, the NRF2 system has become highly energy efficient. Other relevant human-specific co-adaptations are explored. In order to 'test' this composite unifying theory it is important to show that the hypothesis and sub-theories pertain throughout the whole of human evolution and history up till the current era. Corollaries of the composite unifying theory of MetS are examined with respect to past under-nutrition and malnutrition since agriculture began 10,000 years ago. The effects of man-made pollutants on degenerative change are examined. Projections are then made from current to future patterns on the state of 'insufficient micronutrient and/or unbalanced high energy malnutrition with central obesity and metabolic dysregulation' or 'malnubesity'. Forecasts on human health are made on positive, proactive strategies using the composite unifying theory, and are extended to the wider human ecology of food production. A comparison is made with the outlook for humans if current assumptions and the status quo on causes and treatments are maintained. Areas of further research are outlined. A table of suggestions for possible public health action is included.

Impact of lifetime opioid exposure on arterial stiffness and vascular age: cross-sectional and longitudinal studies in men and women

OBJECTIVE

To characterise and compare the potentiation of arterial stiffness and vascular ageing by opioids in men and women.

DESIGN

Cross-sectional and longitudinal studies of 576 clinical controls and 687 opioid-dependent patients (ODP) on 710 and 1305 occasions, respectively, over a total of 2382 days (6.52 years), 2006-2011. Methodology Radial pulse wave analysis with Atcor SphygmoCor system (Sydney).

SETTING

Primary care.

CONTROLS

General practice patients with non-cardiovascular disorders, and university student controls. ODP: Patients undergoing clinical management of their opioid dependence. CONTROLS had lower chronological ages (CAs) than ODP (30.0±0.5 vs 34.5±0.3, mean±SEM, p<0.0001). 69.6% and 67.7% participants were men, and 16% and 92.3% were smokers (p<0.0001) for controls and ODP, respectively. 86.3%, 10.3% and 3.4% of ODP were treated with buprenorphine (6.98±0.21 mg), methadone (63.04±4.01 mg) or implant naltrexone, respectively. Body mass index (BMI) was depressed in ODP.

INTERVENTIONS

Nil.

PRIMARY OUTCOME MEASURES

Vascular Reference Age (RA) and the ratio of vascular age to chronological age (RA/CA).

SECONDARY OUTCOME MEASURES

Arterial stiffness including Augmentation Index.

RESULTS

After BMI adjustment, RA in ODP was higher as a function of CA and of time (both p<0.05). Modelled mean RA in control and ODP was 35.6 and 36.3 years (+1.97%) in men, and 34.5 and 39.2 years (+13.43%) in women, respectively. Changes in RA and major arterial stiffness indices were worse in women both as a factor (p = 0.0036) and in interaction with CA (p = 0.0040). Quadratic, cubic and quartic functions of opioid exposure duration outperformed linear models with RA/CA over CA and over time. The opioid dose-response relationship persisted longitudinally after multiple adjustments from p=0.0013 in men and p=0.0073 in women.

CONCLUSIONS

Data show that lifetime opioid exposure, an interactive cardiovascular risk factor, particularly in women, is related to linear, quadratic, cubic and quartic functions of treatment duration and is consistent with other literature of accelerated ageing in patients with OD.

Naltrexone/bupropion for obesity: an investigational combination pharmacotherapy for weight loss

The mechanism of action of the combination therapy, naltrexone/bupropion (NB), for obesity has not been fully described to date. Weight loss attempts rarely result in long-term success. This is likely a result of complex interactions among multiple peripheral and CNS systems that defend against weight loss, and may explain the overwhelming lack of effective obesity treatments. NB is an investigational combination therapy for obesity that was developed based on evidence that obesity involves alterations in the hypothalamic melanocortin system as well as brain reward systems that influence food craving and mood. Naltrexone and bupropion both have actions in these brain regions that may cause them to influence food intake, food craving, and other aspects of eating behavior that affect body weight. We review the individual actions of naltrexone and bupropion in brain hypothalamic and reward systems, and describe the current in vitro, in vivo, and clinical evidence for how NB influences food intake and produces weight loss.

Clinical factors associated with weight loss outcomes after Roux-en-Y gastric bypass surgery

OBJECTIVE

Gastric bypass surgery is an effective therapy for extreme obesity. However, substantial variability in weight loss outcomes exists that remains largely unexplained. Our objective was to determine whether any commonly collected preoperative clinical variables were associated with weight loss following Roux-en-Y gastric bypass (RYGB) surgery.

METHODS

The analysis was based on a prospectively recruited observational cohort of 2,365 patients who underwent Roux-en-Y gastric bypass surgery from 2004 to 2009. Weight loss was stratified into three major phases, early (0-6 months), nadir, and long-term (>36 months). Multivariate regression models were constructed using a database of over 350 variables.

RESULTS

A total of 12-14 preoperative variables were independently associated (P < 0.05) with each of the temporal weight loss phases. Preoperative variables associated with poorer nadir and long-term weight loss included higher baseline BMI, higher preoperative weight loss, iron deficiency, use of any diabetes medication, nonuse of bupropion medication, no history of smoking, age >50 years, and the presence of fibrosis on liver biopsy.

CONCLUSIONS

Several variables previously associated with poorer weight loss after RYGB surgery including age, baseline BMI, and type 2 diabetes were replicated. Several others suggest possible clinical interventions for postoperative management of RYGB patients to improve weight loss outcomes.

New pharmacological approaches for obesity management

Obesity, which results from an imbalance between calorie intake and expenditure, now affects over 500 million individuals worldwide. Lifestyle and behavioural interventions aimed at reducing calorie intake and/or increasing energy expenditure have limited long-term effectiveness due to complex and persistent hormonal, metabolic and neurochemical adaptations that defend against weight loss and promote weight regain. Surgical treatments for obesity, although highly effective, are unavailable or unsuitable for the majority of individuals with excess adiposity. Accordingly, few effective treatment options are available to most individuals with obesity. In the past, the use of antiobesity drugs, seemingly the logical choice to fill this therapeutic gap, has been limited because of a lack of efficacy, poor long-term adherence rates and serious adverse effects. In 2012, the FDA approved two new medications-lorcaserin and phentermine-topiramate controlled release-and is currently reviewing the resubmission of naltrexone sustained release-bupropion sustained release. This Review presents the available data on the efficacy and safety of these three medications and discusses future perspectives and challenges related to pharmacological weight management.

Therapies for obesity and medication-associated weight gain

Compared to the general population, individuals with psychiatric illness, especially serious and chronic mood and psychotic disorders, are more likely to be overweight or obese, have higher rates of weight-related medical conditions, and have greater non-suicide mortality rates. Lorcaserin (Belviq(®)), phentermine/topiramate combination (Qsymia(®)), and bupropion/naltrexone combination have been demonstrated to be effective for the treatment of obesity, as an adjunct to a reduced-calorie diet and physical activity, although their absolute safety has yet to be established with more widespread use or longer use. Bariatric surgery is an effective approach for morbid obesity, but careful psychiatric assessment before and follow up after surgery is necessary. Behavioral lifestyle interventions to promote weight loss are effective and should be implemented along with or instead of drug therapies or surgery.

The stereoisomer (+)-naloxone potentiates G-protein coupling and feeding associated with stimulation of mu opioid receptors in the parabrachial nucleus

Classically, opioids produce their effects by activating Gi-proteins that inhibit adenylate cyclase activity. Previous studies proposed that mu-opioid receptors can also stimulate adenylate cyclase due to an initial transient coupling to Gs-proteins. Treatment with ultra-low doses of the nonselective opioid antagonist (-)-naloxone or its inactive enantiomer (+)-naloxone blocks this excitatory effect and enhances Gi-coupling. Previously we reported that infusion of the mu-opioid receptor agonist [D-Ala2, N-Me-Phe4, Glycinol5]-Enkephalin (DAMGO) into the mu-opioid receptor expressing lateral parabrachial nucleus increases feeding. Pretreatment with (-)-naloxone blocks this effect. We used this parabrachial circuit as a model to assess cellular actions of ultra-low doses of (-)-naloxone and (+)-naloxone in modifying the effects of DAMGO. Our results showed that an ultra-low concentration of (-)-naloxone (0.001 nM) and several concentrations of (+)-naloxone (0.01-10 nM) enhanced DAMGO-stimulated guanosine-5'-0-(γ-thio)-triphosphate incorporation in parabrachial sections in vitro. Further, we analyzed the relevance of these effects in vivo. In the present study, we show that (+)-naloxone can potentiate DAMGO-induced feeding at doses at which (-)-naloxone was an antagonist. These results implicated (+)-naloxone as a novel tool for studying mu-opioid receptor functions and suggest that (+)-naloxone may have therapeutic value to enhance clinical actions of opiate drugs.

Mechanisms underlying current and future anti-obesity drugs

Regulation of body weight is organized by distributed brain circuits that use a variety of neuropeptides and transmitters, and that are responsive to endocrine and metabolic signals. Targeting of these circuits with novel pharmaceutical drugs would be helpful additions to lifestyle interventions for the treatment of obesity. The recent FDA approval of two anti-obesity drugs holds promise in a field in which previous drugs were removed from clinical use because of unacceptable psychiatric and cardiovascular side effects. Here, the modes of action of anti-obesity drugs are reviewed.

Drug treatment of obesity in cardiovascular disease

Obesity is a significant health problem worldwide and is associated with a number of co-morbidities including type 2 diabetes mellitus, hypertension, dyslipidemia, obstructive sleep apnea, and cardiovascular disease. A number of different pathophysiologic mechanisms including increased inflammation, oxidative stress, and insulin resistance have been associated with initiation and progression of atherosclerotic disease in obese individuals. Lifestyle modifications have provided modest results in weight reduction and the focus of interest has now shifted towards drug development to treat severely obese individuals with a body mass index (BMI) >30 kg/m(2) or those with a BMI >27 kg/m(2) who have additional co-morbidities. Different regimens focusing on dietary absorption or acting centrally to control hunger and food intake have been developed. However, their weight loss effect is, in most cases, modest and this effect is lost once the medication is discontinued. In addition, long-term use of these drugs is limited by significant side effects and lack of long-term safety and efficacy data. Orlistat is the only US FDA-approved medication for long-term use. A number of new medications are currently under investigation in phase III trials with promising preliminary results. This review comments on available anti-obesity pharmacologic regimens, their weight-loss benefit, and their impact on cardiovascular risk factors.