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Chen Y, Ke M, Fang W, Jiang Y, Lin R, Wu W, Huang P, Lin C. Physiologically based pharmacokinetic modeling to predict maternal pharmacokinetics and fetal carbamazepine exposure during pregnancy. Eur J Pharm Sci 2024; 194:106707. [PMID: 38244810 DOI: 10.1016/j.ejps.2024.106707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Revised: 01/11/2024] [Accepted: 01/17/2024] [Indexed: 01/22/2024]
Abstract
Carbamazepine is an antiepileptic drug commonly used in pregnant women, during which the physiological changes may affect its efficacy. The aim of this study was to establish a physiologically based pharmacokinetic (PBPK) model of carbamazepine and its active metabolite carbamazepine-10,11-epoxide, and simulate maternal and fetal pharmacokinetic changes of carbamazepine and carbamazepine-10,11-epoxide in different trimesters and propose dose adjustment. We established pregnancy PBPK models for carbamazepine and carbamazepine-10,11-epoxide in PK-Sim® and Mobi® and validated the models with observed data from clinical reports. The placental transfer parameters obtained using different methods were also imported into the model and compared with the observed data to establish and validate fetal pharmacokinetic curves. The simulated results showed that mean steady-state trough plasma concentration of carbamazepine decreased by 27, 43.1, and 52 % during the first, second, and third trimesters, respectively. Therefore, to achieve an optimum therapeutic concentration, administering at least 1.4, 1.8, and 2.1 times the baseline dose of carbamazepine in the first, second, and third trimesters, respectively can be used as a dose reference. In conclusion, this study established and validated a pregnancy PBPK model of carbamazepine and carbamazepine-10,11-epoxide to assess exposure in pregnant women and fetuses, which provided a reference for the dosage adjustment of carbamazepine during pregnancy.
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Affiliation(s)
- Yuying Chen
- Department of Pharmacy, The First Affiliated Hospital of Fujian Medical University, 20 Cha Zhong M. Rd, Fuzhou 350005, People's Republic of China; Department of Pharmacy, National Regional Medical Center, Binhai Campus of the First Affiliated Hospital, Fujian Medical University, Fuzhou, People's Republic of China
| | - Meng Ke
- Department of Pharmacy, The First Affiliated Hospital of Fujian Medical University, 20 Cha Zhong M. Rd, Fuzhou 350005, People's Republic of China; Department of Pharmacy, National Regional Medical Center, Binhai Campus of the First Affiliated Hospital, Fujian Medical University, Fuzhou, People's Republic of China
| | - Weipeng Fang
- Department of Pharmacy, The First Affiliated Hospital of Fujian Medical University, 20 Cha Zhong M. Rd, Fuzhou 350005, People's Republic of China; Department of Pharmacy, National Regional Medical Center, Binhai Campus of the First Affiliated Hospital, Fujian Medical University, Fuzhou, People's Republic of China
| | - Yaojie Jiang
- Department of Pharmacy, The First Affiliated Hospital of Fujian Medical University, 20 Cha Zhong M. Rd, Fuzhou 350005, People's Republic of China; Department of Pharmacy, National Regional Medical Center, Binhai Campus of the First Affiliated Hospital, Fujian Medical University, Fuzhou, People's Republic of China
| | - Rongfang Lin
- Department of Pharmacy, The First Affiliated Hospital of Fujian Medical University, 20 Cha Zhong M. Rd, Fuzhou 350005, People's Republic of China; Department of Pharmacy, National Regional Medical Center, Binhai Campus of the First Affiliated Hospital, Fujian Medical University, Fuzhou, People's Republic of China
| | - Wanhong Wu
- Department of Pharmacy, The First Affiliated Hospital of Fujian Medical University, 20 Cha Zhong M. Rd, Fuzhou 350005, People's Republic of China; Department of Pharmacy, National Regional Medical Center, Binhai Campus of the First Affiliated Hospital, Fujian Medical University, Fuzhou, People's Republic of China
| | - Pinfang Huang
- Department of Pharmacy, The First Affiliated Hospital of Fujian Medical University, 20 Cha Zhong M. Rd, Fuzhou 350005, People's Republic of China; Department of Pharmacy, National Regional Medical Center, Binhai Campus of the First Affiliated Hospital, Fujian Medical University, Fuzhou, People's Republic of China
| | - Cuihong Lin
- Department of Pharmacy, The First Affiliated Hospital of Fujian Medical University, 20 Cha Zhong M. Rd, Fuzhou 350005, People's Republic of China; Department of Pharmacy, National Regional Medical Center, Binhai Campus of the First Affiliated Hospital, Fujian Medical University, Fuzhou, People's Republic of China.
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2
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Kus M, Ibragimow I, Piotrowska-Kempisty H. Caco-2 Cell Line Standardization with Pharmaceutical Requirements and In Vitro Model Suitability for Permeability Assays. Pharmaceutics 2023; 15:2523. [PMID: 38004503 PMCID: PMC10674574 DOI: 10.3390/pharmaceutics15112523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Revised: 10/19/2023] [Accepted: 10/19/2023] [Indexed: 11/26/2023] Open
Abstract
The Caco-2 cell line derived from human colon carcinoma is commonly used to assess the permeability of compounds in in vitro conditions. Due to the significant increase in permeability studies using the Caco-2 cell line in recent years, the need to standardize this biological model seems necessary. The pharmaceutical requirements define only the acceptance criteria for the validation of the Caco-2 cell line and do not specify the protocol for its implementation. Therefore, the aim of this study is to review the conditions for permeability studies across the Caco-2 monolayer reported in the available literature concerning validation guidelines. We summarized the main aspects affecting the validation process of the Caco-2 cell line, including the culture conditions, cytotoxicity, cell differentiation process, and monolayer transport conditions, and the main conclusions may be useful in developing individual methods for preparing the cell line for validation purposes and further permeability research.
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Affiliation(s)
- Marta Kus
- Department of Toxicology, Poznan University of Medical Sciences, 30 Dojazd St., 60-631 Poznan, Poland;
- Research and Development Department of Ethifarm, Ethifarm Manufacturing Plant, 9 Stefana Zeromskiego St., 60-544 Poznan, Poland;
| | - Izabela Ibragimow
- Research and Development Department of Ethifarm, Ethifarm Manufacturing Plant, 9 Stefana Zeromskiego St., 60-544 Poznan, Poland;
| | - Hanna Piotrowska-Kempisty
- Department of Toxicology, Poznan University of Medical Sciences, 30 Dojazd St., 60-631 Poznan, Poland;
- Department of Basic and Preclinical Science, Institute of Veterinary Medicine, Nicolaus Copernicus University in Toruń, 7 Gagarina St., 87-100 Torun, Poland
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3
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García MA, Cristofoletti R, Abrahamsson B, Groot DW, Parr A, Polli JE, Mehta M, Shah VP, Tomakazu T, Dressman JB, Langguth P. Biowaiver Monograph for Immediate-Release Solid Oral Dosage Forms: Carbamazepine. J Pharm Sci 2021; 110:1935-1947. [PMID: 33610571 DOI: 10.1016/j.xphs.2021.02.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 01/28/2021] [Accepted: 02/03/2021] [Indexed: 10/22/2022]
Abstract
Literature relevant to assessing whether BCS-based biowaivers can be applied to immediate release (IR) solid oral dosage forms containing carbamazepine as the single active pharmaceutical ingredient are reviewed. Carbamazepine, which is used for the prophylactic therapy of epilepsy, is a non-ionizable drug that cannot be considered "highly soluble" across the range of pH values usually encountered in the upper gastrointestinal tract. Furthermore, evidence in the open literature suggests that carbamazepine is a BCS Class 2 drug. Nevertheless, the oral absolute bioavailability of carbamazepine lies between 70 and 78% and both in vivo and in vitro data support the classification of carbamazepine as a highly permeable drug. Since the therapeutic and toxic plasma level ranges overlap, carbamazepine is considered to have a narrow therapeutic index. For these reasons, a BCS based biowaiver for IR tablets of carbamazepine cannot be recommended. Interestingly, in nine out of ten studies, USP dissolution conditions (900 mL water with 1% SLS, paddle, 75 rpm) appropriately discriminated among bioinequivalent products and this may be a way forward to predicting whether a given formulation will be bioequivalent to the comparator product.
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Affiliation(s)
- Mauricio A García
- Pharmaceutical Technology and Biopharmaceutics, Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg University, Mainz, Germany
| | - Rodrigo Cristofoletti
- Center for Pharmacometrics and Systems Pharmacology, Department of Pharmaceutics, College of Pharmacy, University of Florida, Orlando, FL, USA
| | | | - Dirk W Groot
- RIVM (National Institute for Public Health and the Environment), Bilthoven, the Netherlands
| | | | - James E Polli
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, MD, USA
| | - Mehul Mehta
- Division of Clinical Pharmacology, Centre for Drug Evaluation and Research, United States Food and Drug Administration, Silver Spring, MD, USA
| | - Vinod P Shah
- International Pharmaceutical Federation (FIP), The Hague, the Netherlands
| | - Tajiri Tomakazu
- Pharmaceutical Science & Technology Laboratories, Astellas Pharma Inc, Ibaraki, Japan
| | - Jennifer B Dressman
- Fraunhofer Institute of Translational Medicine and Pharmacology, ITMP, Institute of Pharmaceutical Technology, Johann Wolfgang Goethe University, Frankfurt am Main, Germany.
| | - Peter Langguth
- Pharmaceutical Technology and Biopharmaceutics, Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg University, Mainz, Germany.
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4
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Jarc T, Novak M, Hevir N, Rižner TL, Kreft ME, Kristan K. Demonstrating suitability of the Caco-2 cell model for BCS-based biowaiver according to the recent FDA and ICH harmonised guidelines. J Pharm Pharmacol 2019; 71:1231-1242. [DOI: 10.1111/jphp.13111] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2018] [Accepted: 05/05/2019] [Indexed: 01/10/2023]
Abstract
Abstract
Objective
According to the regulatory guidelines, one of the critical steps in using in-vitro permeability methods for permeability classification is to demonstrate the suitability of the method. Here, suitability of the permeability method by using a monolayer of cultured epithelial cells was verified with different criteria.
Methods
Imaging with a transmission electron microscope was used for characterisation of the cells. Monolayer integrity was confirmed by transepithelial electrical resistance measurements and permeability of zero permeability marker compounds. Real-time polymerase chain reaction was employed to evaluate expression levels of 84 known transporters. Samples for bidirectional permeability determination were quantified by ultra-performance liquid chromatography.
Key findings
The Caco-2 cells grow in an intact monolayer and morphologically resemble enterocytes. Genes of 84 known transporters were expressed at different levels; furthermore, expression was time depended. Functional expression of efflux transporter P-glycoprotein was confirmed. We established a correlation between permeability coefficients of 21 tested drug substances ranging from low, moderate and high absorption with human fraction absorbed literature data (R2 = 0.84).
Conclusions
Assay standardisation assures the consistency of experimental data. Only such fully characterised model has the ability to accurately predict drug's intestinal permeability at the early stage of research or for the BCS-based biowaiver application.
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Affiliation(s)
- Tina Jarc
- Institute of Cell Biology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | | | - Neli Hevir
- Biopharma Process & Product Development, Lek Pharmaceuticals d.d., Mengeš, Slovenia
| | - Tea Lanišnik Rižner
- Institute of Biochemistry, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Mateja Erdani Kreft
- Institute of Cell Biology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Katja Kristan
- Institute of Biochemistry, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
- Sandoz Development Center Slovenia, Lek Pharmaceuticals, d.d., Ljubljana, Slovenia
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5
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Lappin G. Approaches to intravenous clinical pharmacokinetics: Recent developments with isotopic microtracers. J Clin Pharmacol 2015; 56:11-23. [DOI: 10.1002/jcph.569] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 06/08/2015] [Indexed: 12/16/2022]
Affiliation(s)
- Graham Lappin
- Visiting Professor of Pharmacology, School of Pharmacy; University of Lincoln; Lincoln UK
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6
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Ahmed GF, Brundage RC, Marino SE, Cloyd JC, Leppik IE, Pennell PB, Ramsay RE, Birnbaum AK. Population pharmacokinetics of unbound and total drug concentrations following intravenously administered carbamazepine in elderly and younger adult patients with epilepsy. J Clin Pharmacol 2013; 53:276-84. [PMID: 23408495 DOI: 10.1002/jcph.8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2012] [Accepted: 06/28/2012] [Indexed: 11/08/2022]
Abstract
The objective of the study was to investigate the pharmacokinetics (PK) of unbound and total plasma carbamazepine (CBZ) concentrations following simultaneous administration of intravenous and oral formulations. We tested the hypothesis that age-related alterations in physiology and patient characteristics influence CBZ disposition and protein binding. Patients (n = 113) on maintenance therapy received a 100 mg dose of a novel, intravenous, stable-labeled (SL) CBZ formulation as partial replacement of their morning CBZ dose. A two-compartment model described unbound and total SL-CBZ data. The stable-labeled intravenous dosing methodology enabled the estimation of the CBZ clearance (CL) and volumes of distribution. The CL of CBZ was dependent on race through the model equation unbound CL (L/hour) = 11.2 × (1.30)(Race); where Race = 1 for Caucasian, 0 for African American. Total body weight explained 57% and 70% of the interindividual variability in the central and peripheral volumes of distribution, respectively. Age, sex, smoking, plasma albumin, and alpha 1-acid glycoprotein concentrations had no effect on CL, binding or volumes of distribution. The model was evaluated via bootstrap and predictive check. Results may support race specific dosing for CBZ where an average African-American individual would receive 70% of the standard dose prescribed for the Caucasian person.
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Affiliation(s)
- Ghada F Ahmed
- Department of Experimental and Clinical Pharmacology, University of Minnesota, Minneapolis, MN, USA
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7
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Peternel L, Kristan K, Petruševska M, Rižner TL, Legen I. Suitability of Isolated Rat Jejunum Model for Demonstration of Complete Absorption in Humans for BCS-Based Biowaiver Request. J Pharm Sci 2012; 101:1436-49. [DOI: 10.1002/jps.23027] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2011] [Revised: 11/22/2011] [Accepted: 12/02/2011] [Indexed: 12/18/2022]
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8
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Xu C, Zou M, Liu Y, Ren J, Tian Y, Yan J, Wang Y, Cheng G. Pharmacokinetics of carbamazepine polymorphs and dihydrate in rats, related to dogs and humans. Arch Pharm Res 2011; 34:1973-82. [DOI: 10.1007/s12272-011-1118-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2011] [Revised: 06/18/2011] [Accepted: 06/30/2011] [Indexed: 11/24/2022]
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9
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Jover Botella A, Márquez Peiró J, González Loreiro M, Pitaluga Poveda L, Selva Otaolaurruchi J. Análisis de la estabilidad de dos suspensiones orales de carbamazepina. FARMACIA HOSPITALARIA 2011; 35:28-31. [DOI: 10.1016/j.farma.2010.03.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2010] [Revised: 03/23/2010] [Accepted: 03/26/2010] [Indexed: 11/26/2022] Open
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10
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Hemenway JN, Stella VJ. In Vitro and In Vivo Evaluation of a Novel Water-Soluble N-Glycyl Prodrug (N-GLY-CBZ) of Carbamazepine. J Pharm Sci 2010; 99:4565-75. [DOI: 10.1002/jps.22171] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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11
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Nishimuta H, Sato K, Mizuki Y, Yabuki M, Komuro S. Prediction of the Intestinal First-Pass Metabolism of CYP3A Substrates in Humans Using Cynomolgus Monkeys. Drug Metab Dispos 2010; 38:1967-75. [DOI: 10.1124/dmd.110.034561] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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12
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Pharmacodynamics of carbamazepine-mediated induction of CYP3A4, CYP1A2, and Pgp as assessed by probe substrates midazolam, caffeine, and digoxin. Clin Pharmacol Ther 2007; 84:52-62. [PMID: 17971810 DOI: 10.1038/sj.clpt.6100431] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The aim of this study was to develop a model describing the carbamazepine autoinduction and the carbamazepine-mediated induction of CYP3A4, CYP1A2, and P-glycoprotein. Seven healthy volunteers were dosed with carbamazepine over 16 consecutive days. The CYP3A4, CYP1A2, and P-glycoprotein activities were assessed, using midazolam, caffeine, and digoxin as probe substrates, on 12 occasions, covering the preinduced state and the onset and termination of the induction process. The data were evaluated using a mechanistic pharmacokinetic approach in NONMEM. The induction processes were described using turnover models, with carbamazepine and carbamazepine-10,11-epoxide as the driving force of the induction. The half-lives of CYP3A4 and CYP1A2 were estimated to be 70 and 105 h, respectively. P-glycoprotein was not affected by the carbamazepine treatment. The possibility of modeling the pharmacodynamics of enzyme induction using a turnover model was illustrated, and the time course of the process was estimated with good precision.
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13
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Lindenberg M, Kopp S, Dressman JB. Classification of orally administered drugs on the World Health Organization Model list of Essential Medicines according to the biopharmaceutics classification system. Eur J Pharm Biopharm 2005; 58:265-78. [PMID: 15296954 DOI: 10.1016/j.ejpb.2004.03.001] [Citation(s) in RCA: 493] [Impact Index Per Article: 25.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2004] [Accepted: 02/05/2004] [Indexed: 01/01/2023]
Abstract
Since its inception in 1995, the biopharmaceutical classification system (BCS) has become an increasingly important tool for regulation of drug products world-wide. Until now, application of the BCS has been partially hindered by the lack of a freely available and accurate database summarising solubility and permeability characteristics of drug substances. In this report, orally administered drugs on the Model list of Essential Medicines of the World Health Organization (WHO) are assigned BCS classifications on the basis of data available in the public domain. Of the 130 orally administered drugs on the WHO list, 61 could be classified with certainty. Twenty-one (84%) of these belong to class I (highly soluble, highly permeable), 10 (17%) to class II (poorly soluble, highly permeable), 24 (39%) to class III (highly soluble, poorly permeable) and 6 (10%) to class IV (poorly soluble, poorly permeable). A further 28 drugs could be provisionally assigned, while for 41 drugs insufficient or conflicting data precluded assignment to a specific BCS class. A total of 32 class I drugs (either certain or provisional classification) were identified. These drugs can be further considered for biowaiver status (drug product approval based on dissolution tests rather than bioequivalence studies in humans).
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Affiliation(s)
- Marc Lindenberg
- Department of Pharmaceutical Technology, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany
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14
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Caraco Y, Zylber-Katz E, Berry EM, Levy M. Carbamazepine pharmacokinetics in obese and lean subjects. Ann Pharmacother 1995; 29:843-7. [PMID: 8547729 DOI: 10.1177/106002809502900902] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
OBJECTIVE To compare carbamazepine pharmacokinetic parameters between obese and lean subjects following the administration of a single 200-mg tablet. DESIGN Single-dose intervention, open study. SETTING Teaching university hospital. SUBJECTS Eighteen obese (group A) otherwise healthy subjects, referred to the metabolic outpatient clinic, and 13 healthy lean (group B) volunteers. Inclusion criterion for the obese subjects was a body mass index (BMI = weight/height2) of more than 30 kg/m2. In the obese group, mean +/- SD total body weight (TBW), BMI, and percent of ideal body weight (IBW) were 111.4 +/- 19.9 kg, 38.8 +/- 6.0 kg/m2, and 182.7% +/- 30.7%, respectively. These values were significantly greater than the respective values of 63.2 +/- 8.3 kg, 22.4 +/- 1.6 kg/m2, and 105.8% +/- 5.8% obtained in the lean group (p < 0.001). INTERVENTION Single-dose oral administration of carbamazepine 200-mg tablet (Teril, Taro, Israel). OUTCOMES Carbamazepine elimination half-life (t1/2), apparent volume of distribution (Varea/F), and its oral clearance (Clpo/F) were derived from the drug concentration-time curves. RESULTS Carbamazepine Varea/F and t1/2 were significantly greater in group A than in group B (98.4 +/- 26.9 vs. 60.7 +/- 8.5 L, respectively, p < 0.001; and 59.4 +/- 14.7 vs. 31.0 +/- 5.0 h, respectively, p < 0.001), but its Clpo/F was reduced only slightly in obese as compared with lean subjects (19.8 +/- 5.2 vs. 23.0 +/- 4.6 mL/min, respectively, p = 0.07). Correction for IBW yielded similar results for Varea/F and t1/2, but Clpo/F per kg of IBW was significantly smaller in the obese than in the lean subjects (0.32 +/- 0.07 vs. 0.39 +/- 0.06 mL/min/kg of IBW, respectively, p < 0.02). Linear correlations were observed between Varea/F and TBW for both group A (r = 0.92, p < 0.001) and group B (r = 0.77, p < 0.002). CONCLUSIONS In comparison with lean subjects, carbamazepine Varea/F is significantly greater in obese subjects and its t1/2 is markedly prolonged. The minor nonsignificant effect of obesity on carbamazepine Clpo/F suggests that in obese subjects the carbamazepine daily dose should be based on IBW, not on TBW.
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Affiliation(s)
- Y Caraco
- Clinical Pharmacology Unit, Hadassah University Hospital, Jerusalem, Israel
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15
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Kayali A, Tuğlular I, Ertaş M. Pharmacokinetics of carbamazepine. Part I: A new bioequivalency parameter based on a relative bioavailability trial. Eur J Drug Metab Pharmacokinet 1994; 19:319-25. [PMID: 7737233 DOI: 10.1007/bf03188858] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The relative bioavailability of three carbamazepine generics available in Turkey, were investigated in 5 healthy male volunteers. When issuing a license to any drug, FDA stipulates at most a difference of 20% from the reference drug only in peak concentration and AUC (area under the curve). This condition may cause some problems, as two generics of the same drug can yield the same total amount (AUC) and can be accepted as bioequivalent despite different curves of the two drugs. In this study, to compare drugs from the point of view of bioequivalency, we suggest a new calculation method that takes into account ka (absorption rate constant), ke (elimination rate constant), tmax (time to peak), MRT (mean residence time) and AUC. Should this formula be used in comparison of bioequivalency, all the parameters related to the kinetics of drugs will have been taken into account. The suggested parameter is: [formula: see text] However, amongst three carbamazepine generics-Tegretol, Temporol and Karazepin-the most desirable curve is that of Tegretol, while bioavailability values are respectively F = 0.86, 0.93, 0.85 and AUC = 145, 161, 127. The A parameter values are respectively 49.3, 47.2, 42.9.
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Affiliation(s)
- A Kayali
- Department of Analytical Chemistry, Ege University, Izmir, Turkey
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16
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Dobson RL, Kelm GR, Neal DM. Automated gas chromatography/tandem mass spectrometry assay for tebufelone and a 13C,(18)O-labeled analog in plasma: applicabilityto absolute bioavailability determination. BIOLOGICAL MASS SPECTROMETRY 1994; 23:75-81. [PMID: 8123692 DOI: 10.1002/bms.1200230206] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
An automated capillary gas chromatography/tandem mass spectrometry (GC/MS/MS) assay for the simultaneous quantitation of tebufelone (TE) and 13C, (18)O-labeled TE (TE-CO) in plasma was developed. This method permits the use of stable isotope coadministration (TE and TE-CO dosed concurrently via peroral and intravenous routes, respectively) for the determination of TE absolute bioavailability. The selectivity of MS/MS conducted on a triple-quadrupole instrument allowed minimal sample preparation and rapid analysis. Electron ionization produced molecular ions (M+) for TE, TE-CO, and the 3-methyl-TE internal standard which were selected in Q1 to undergo collisionally activated dissociation in Q2. Quantitation was achieved through monitoring product ions at m/z 248, 251 and 248, respectively, in Q3. A 2-1000 ng per sample (40 pg to 20 ng injected) quantitation range provided access to an effective 1-5000 p.p.b. plasma concentration range (0.2-2 g samples) for both TE and TE-CO. The assay showed no bias and less than 8% relative standard deviation over the entire range. The method was used to determine plasma levels of TE and TE-CO in four dogs receiving 2.5:2.5 mg/kg TE:TE-CO, intravenously. The pharmacokinetics of both isotopomers proved to be identical, indicating no isotope effect and verifying the chemical stability of the (18)O-carbonyl label under these dosing conditions. In addition, the applicability of this analytical approach to the determination of TE peroral bioavailability was initially tested in dogs.
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Affiliation(s)
- R L Dobson
- Procter & Gamble Pharmaceuticals, Miami Valley Laboratories, Cincinnati, OH 45239-8707
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