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Milosavljević F, Manojlović M, Matković L, Molden E, Ingelman-Sundberg M, Leucht S, Jukić MM. Pharmacogenetic Variants and Plasma Concentrations of Antiseizure Drugs: A Systematic Review and Meta-Analysis. JAMA Netw Open 2024; 7:e2425593. [PMID: 39115847 PMCID: PMC11310823 DOI: 10.1001/jamanetworkopen.2024.25593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Accepted: 06/04/2024] [Indexed: 08/11/2024] Open
Abstract
Importance Precise estimation of a patient's drug metabolism capacity is important for antiseizure dose personalization. Objective To quantify the differences in plasma concentrations for antiseizure drugs associated with variants of genes encoding drug metabolizing enzymes. Data Sources PubMed, Clinicaltrialsregister.eu, ClinicalTrials.gov, International Clinical Trials Registry Platform, and CENTRAL databases were screened for studies from January 1, 1990, to September 30, 2023, without language restrictions. Study Selection Two reviewers performed independent study screening and assessed the following inclusion criteria: appropriate genotyping was performed, genotype-based categorization into subgroups was possible, and each subgroup contained at least 3 participants. Data Extraction and Synthesis The Meta-analysis of Observational Studies in Epidemiology (MOOSE) guidelines were followed for data extraction and subsequent quality, validity, and risk-of-bias assessments. The results from the included studies were pooled with random-effect meta-analysis. Main Outcomes and Measures Plasma concentrations of antiseizure drugs were quantified with the dose-normalized area under the concentration-time curve, the dose-normalized steady state concentration, or the concentrations after a single dose at standardized dose and sampling time. The ratio of the means was calculated by dividing the mean drug plasma concentrations of carriers and noncarriers of the pharmacogenetic variant. Results Data from 98 studies involving 12 543 adult participants treated with phenytoin, valproate, lamotrigine, or carbamazepine were analyzed. Studies were mainly conducted within East Asian (69 studies) or White or European (15 studies) cohorts. Significant increases of plasma concentrations compared with the reference subgroup were observed for phenytoin, by 46% (95% CI, 33%-61%) in CYP2C9 intermediate metabolizers, 20% (95% CI, 17%-30%) in CYP2C19 intermediate metabolizers, and 39% (95% CI, 24%-56%) in CYP2C19 poor metabolizers; for valproate, by 12% (95% CI, 4%-20%) in CYP2C9 intermediate metabolizers, 12% (95% CI, 2%-24%) in CYP2C19 intermediate metabolizers, and 20% (95% CI, 2%-41%) in CYP2C19 poor metabolizers; and for carbamazepine, by 12% (95% CI, 3%-22%) in CYP3A5 poor metabolizers. Conclusions and Relevance This systematic review and meta-analysis found that CYP2C9 and CYP2C19 genotypes encoding low enzymatic capacity were associated with a clinically relevant increase in phenytoin plasma concentrations, several pharmacogenetic variants were associated with statistically significant but only marginally clinically relevant changes in valproate and carbamazepine plasma concentrations, and numerous pharmacogenetic variants were not associated with statistically significant differences in plasma concentrations of antiseizure drugs.
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Affiliation(s)
- Filip Milosavljević
- Department of Physiology, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia
- Department of Psychiatry and Psychotherapy, School of Medicine, Technische Universität München, München, Germany
| | - Marina Manojlović
- Department of Physiology, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia
| | - Lena Matković
- Department of Physiology, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia
- Institute for Mental Health, Belgrade, Serbia
| | - Espen Molden
- Section for Pharmacology and Pharmaceutical Biosciences, Department of Pharmacy, University of Oslo, Oslo, Norway
- Center for Psychopharmacology, Diakonhjemmet Hospital, Oslo, Norway
| | - Magnus Ingelman-Sundberg
- Pharmacogenetics Section, Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Stefan Leucht
- Department of Psychiatry and Psychotherapy, School of Medicine, Technische Universität München, München, Germany
| | - Marin M. Jukić
- Department of Physiology, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia
- Pharmacogenetics Section, Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
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Kato H, Hagihara M, Asai N, Mikamo H, Iwamoto T. Evaluation of effectiveness, hyperkalaemia, and hepatotoxicity of trimethoprim-sulphamethoxazole prophylaxis for Pneumocystis jirovecii pneumonia in paediatric patients: A single-centre retrospective study. Int J Antimicrob Agents 2024; 63:107151. [PMID: 38508538 DOI: 10.1016/j.ijantimicag.2024.107151] [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: 12/04/2023] [Revised: 03/04/2024] [Accepted: 03/15/2024] [Indexed: 03/22/2024]
Abstract
BACKGROUND American guidelines recommend trimethoprim-sulphamethoxazole (TMP-SMX) for preventing Pneumocystis jirovecii pneumonia (PJP) in paediatric patients at doses of 5-10 mg/kg/d of the TMP component, administered either daily, three times weekly, or twice weekly. However, limited studies describe the effectiveness and safety of these prophylactic regimens. Our study aimed to assess the clinical effectiveness and incidence of adverse events associated with each TMP-SMX regimen in paediatric patients, and to identify risk factors for adverse events. METHODS We collected data regarding the onset of PJP, hyperkalaemia, and hepatotoxicity in patients aged 0-18 years who underwent prophylaxis with TMP-SMX from July 2018 to June 2023. RESULTS A total of 215 paediatric patients met the inclusion criteria. No patients developed PJP. Hyperkalaemia occurred in 14.7%, patients receiving TMP-SMX daily, 15.4% receiving it three times weekly, and 15.5% receiving it twice weekly. Hepatotoxicity was most frequent in patients receiving TMP-SMX twice weekly (19%), followed by those receiving it three times weekly (7.7%), and daily (5.9%). Younger patients were significantly more prone to developing hyperkalaemia or hepatotoxicity. Patients aged <1 year had the highest incidences of hyperkalaemia (56.5%), and those aged 1-2 years had the highest incidence of hepatotoxicity (25%). CONCLUSIONS No patient developed PJP under various dosage prophylactic regimens of TMP-SMX. However, our findings suggest the need to monitor potassium levels and hepatic function in patients undergoing any of the three TMP-SMX regimens. In particular, patients aged <1 year old and 1-2 years old face a higher risk of hyperkalaemia and hepatotoxicity, respectively.
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Affiliation(s)
- Hideo Kato
- Department of Pharmacy, Mie University Hospital, Tsu, Mie, Japan; Division of Clinical Medical Science, Department of Clinical Pharmaceutics, Mie University Graduate School of Medicine, Tsu, Mie, Japan; Department of Clinical Infectious Diseases, Aichi Medical University, Nagakute, Aichi, Japan.
| | - Mao Hagihara
- Department of Molecular Epidemiology and Biomedical Sciences, Aichi Medical University Hospital, Nagakute, Aichi, Japan
| | - Nobuhiro Asai
- Department of Clinical Infectious Diseases, Aichi Medical University, Nagakute, Aichi, Japan
| | - Hiroshige Mikamo
- Department of Clinical Infectious Diseases, Aichi Medical University, Nagakute, Aichi, Japan
| | - Takuya Iwamoto
- Department of Pharmacy, Mie University Hospital, Tsu, Mie, Japan; Division of Clinical Medical Science, Department of Clinical Pharmaceutics, Mie University Graduate School of Medicine, Tsu, Mie, Japan
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Okamoto G, Furuya E, Terada K, Yasukawa K, Takanashi JI, Kobayashi E. Fosphenytoin dosing regimen including optimal timing for the measurement of serum phenytoin concentration in pediatric patients. Brain Dev 2022; 44:725-731. [PMID: 35879140 DOI: 10.1016/j.braindev.2022.06.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 06/02/2022] [Accepted: 06/30/2022] [Indexed: 11/19/2022]
Abstract
INTRODUCTION We aimed to evaluate the pediatric fosphenytoin dosing regimen, including optimal timing for the measurement of total serum phenytoin concentration (CPHT). METHODS We retrospectively investigated pediatric patients with status epilepticus or seizure clusters treated with fosphenytoin between April 2013 and March 2018. Two CPHT measurements were analyzed, one 2-4 h after the loading dose and another before the second dose. Individual pharmacokinetic parameters were estimated using the Bayesian method and were used to simulate CPHT. RESULTS The present study involved 12 pediatric patients; the loading dose of fosphenytoin was 22.1 (17.2-27.2) mg/kg. The CPHT was 13.4 (8.6-18.9) μg/mL 2-4 h after the loading dose. The CPHT estimated from individual pharmacokinetic parameters 12 and 24 h after the loading dose was 9.5 (6.7-14.2) and 5.8 (3.7-10.0) μg/mL, respectively. If fosphenytoin was administered at a loading dose of 22.5 mg/kg and a maintenance dose of 5 or 7.5 mg/kg (administered every 12 h, starting 12 h after the loading dose), then the CPHT on day 8 was estimated to be 5.74 (2.6-15.4) μg/mL at 5 mg/kg and 13.9 (5.7-31.0) μg/mL at 7.5 mg/kg. CONCLUSIONS In pediatric patients, a maintenance dose of fosphenytoin should be started 12 h after the loading dose, and a maintenance dose of 5-7.5 mg/kg/dose every 12 h may be better than every 24 h. We recommend measuring CPHT at 2 and 12 h after the loading dose to simplify and safely adjust the dosage in clinical practice.
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Affiliation(s)
- Go Okamoto
- Department of Pharmacy, Tokyo Women's Medical University, Yachiyo Medical Center, Chiba, Japan.
| | - Emari Furuya
- Department of Pharmacy, Tokyo Women's Medical University, Yachiyo Medical Center, Chiba, Japan
| | - Kanae Terada
- Department of Pharmacy, Tokyo Women's Medical University, Yachiyo Medical Center, Chiba, Japan
| | - Kumi Yasukawa
- Pediatric Intensive Care Unit, Tokyo Women's Medical University, Yachiyo Medical Center, Chiba, Japan
| | - Jun-Ichi Takanashi
- Department of Pediatrics, Tokyo Women's Medical University, Yachiyo Medical Center, Chiba, Japan
| | - Emiko Kobayashi
- Department of Pharmacy, Tokyo Women's Medical University, Yachiyo Medical Center, Chiba, Japan
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Kanjanasilp J, Sawangjit R, Phanthaisong S, Borihanthanawuth W. A meta-analysis of effects of CYP2C9 and CYP2C19 polymorphisms on phenytoin pharmacokinetic parameters. Pharmacogenomics 2021; 22:629-640. [PMID: 34060344 DOI: 10.2217/pgs-2020-0151] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Aim: Phenytoin is metabolized through CYP2C9 and CYP2C19. Polymorphisms of CYP2C9 and CYP2C19 may increase plasma concentration and side effects. Materials & methods: Systematic review and meta-analysis were performed to evaluate the effects of CYP2C9 and CYP2C19 polymorphism on pharmacokinetic parameters. PubMed, Science Direct, Cochrane library, and Thai databases were systematically searched. Results: Eight observational studies, comprising a total of 633 patients were included. Michaelis-Menten constant was significantly higher in the polymorphism of CYP2C9IM/CYP2C19EM and CYP2C9IM/CYP2C19IM groups as compared with the control groups (CYP2C9EM/CYP2C19EM) at 2.16 and 1.55 mg/l (p < 0.00001, p < 0.0001). The maximum rate of action was significantly lower in the control groups as compared with the polymorphism of CYP2C9IM/CYP2C19EM and CYP2C9IM/CYP2C19IM groups at 3.10 and 3.53 mg/kg/day (p = 0.00001, <0.0001). Conclusion: The dosage regimen for patients in the CYP2C9IM group to achieve phenytoin therapeutic levels was 2.1-3.4 mg/kg/day.
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Affiliation(s)
- Juntip Kanjanasilp
- Clinical Trials & Evidence-Based Synthesis Research Unit, Faculty of Pharmacy, Mahasarakham University, Maha Sarakham, 44150, Thailand
| | - Ratree Sawangjit
- Clinical Trials & Evidence-Based Synthesis Research Unit, Faculty of Pharmacy, Mahasarakham University, Maha Sarakham, 44150, Thailand
| | - Sirikhwan Phanthaisong
- Clinical Trials & Evidence-Based Synthesis Research Unit, Faculty of Pharmacy, Mahasarakham University, Maha Sarakham, 44150, Thailand
| | - Wongvaruth Borihanthanawuth
- Clinical Trials & Evidence-Based Synthesis Research Unit, Faculty of Pharmacy, Mahasarakham University, Maha Sarakham, 44150, Thailand
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Matsumoto S, Uehara S, Kamimura H, Ikeda H, Maeda S, Hattori M, Nishiwaki M, Kato K, Yamazaki H. Human total clearance values and volumes of distribution of typical human cytochrome P450 2C9/19 substrates predicted by single-species allometric scaling using pharmacokinetic data sets from common marmosets genotyped for P450 2C19. Xenobiotica 2021; 51:479-493. [PMID: 33455494 DOI: 10.1080/00498254.2020.1871113] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Common marmosets (Callithrix jacchus) are small non-human primates that genetically lack cytochrome P450 2C9 (CYP2C9). Polymorphic marmoset CYP2C19 compensates by mediating oxidations of typical human CYP2C9/19 substrates.Twenty-four probe substrates were intravenously administered in combinations to marmosets assigned to extensive or poor metaboliser (PM) groups by CYP2C19 genotyping. Eliminations from plasma of cilomilast, phenytoin, repaglinide, tolbutamide, and S-warfarin in the CYP2C19 PM group were significantly slow; these drugs are known substrates of human CYP2C8/9/19.Human total clearance values and volumes of distribution of the 24 test compounds were extrapolated using single-species allometric scaling with experimental data from marmosets and found to be mostly comparable with the reported values.Human total clearance values and volumes of distribution of 15 of the 24 test compounds similarly extrapolated using reported data sets from cynomolgus or rhesus monkeys were comparable to the present predicted results, especially to those based on data from PM marmosets.These results suggest that single-species allometric scaling using marmosets, being small, has advantages over multiple-species-based allometry and could be applicable for pharmacokinetic predictions at the discovery stage of drug development.
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Affiliation(s)
- Shogo Matsumoto
- Pharmaceutical Research Labs., Meiji Seika Pharma Co., Ltd., Yokohama, Japan
| | - Shotaro Uehara
- Central Institute for Experimental Animals, Kawasaki, Japan.,Pharmaceutical University, Machida, Tokyo, Japan
| | - Hidetaka Kamimura
- Central Institute for Experimental Animals, Kawasaki, Japan.,Business Promotion Dept., CLEA Japan, Inc., Tokyo, Japan
| | - Hiroshi Ikeda
- Tokyo Animal & Diet Dept., CLEA Japan, Inc., Tokyo, Japan
| | - Satoshi Maeda
- Yaotsu Breeding Center, CLEA Japan, Inc., Gifu, Japan
| | | | - Megumi Nishiwaki
- Fuji Technical Service Center, CLEA Japan, Inc.., Shizuoka, Japan
| | - Kazuhiko Kato
- Pharmaceutical Research Labs., Meiji Seika Pharma Co., Ltd., Yokohama, Japan
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Hikino K, Ozeki T, Koido M, Terao C, Kamatani Y, Mizukawa Y, Shiohara T, Tohyama M, Azukizawa H, Aihara M, Nihara H, Morita E, Murakami Y, Kubo M, Mushiroda T. HLA-B*51:01 and CYP2C9*3 Are Risk Factors for Phenytoin-Induced Eruption in the Japanese Population: Analysis of Data From the Biobank Japan Project. Clin Pharmacol Ther 2019; 107:1170-1178. [PMID: 31646624 DOI: 10.1002/cpt.1706] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 10/13/2019] [Indexed: 12/19/2022]
Abstract
CYP2C9*3 and HLA-B alleles are reportedly associated with phenytoin-induced eruption in some East Asian populations; however, this finding is not readily applicable to the Japanese population. Thus, we aimed to investigate the risk alleles using samples and data from BioBank Japan. A total of 747 patients (24 cases and 723 tolerant controls) were selected for analysis. Case-control association studies were conducted, using CYP2C9*3, CYP2C9*27, CYP2C19*2, CYP2C19*3, and HLA-B allele genotype data. CYP2C9*3 carrier status was significantly associated with phenytoin-induced eruption (P = 0.0022, odds ratio 7.05, 95% confidence interval, 2.44-20.4). HLA-B*51:01 showed the most prominent association (P = 0.010, odds ratio 3.19, 95% confidence interval, 1.37-7.48). Including both of these features improved predictive performance, measured as area under the receiver operating characteristic curve, by 10%. CYP2C9*3 and HLA-B*51:01 allele carrier statuses are significantly associated with phenytoin-induced eruption; thus, checking this carrier status before prescription would decrease the incidence of phenytoin-induced eruption in clinical practice.
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Affiliation(s)
- Keiko Hikino
- Laboratory for Pharmacogenomics, RIKEN Center for Integrative Medical Sciences, Yokohama City, Kanagawa, Japan
| | - Takeshi Ozeki
- Laboratory for Pharmacogenomics, RIKEN Center for Integrative Medical Sciences, Yokohama City, Kanagawa, Japan
| | - Masaru Koido
- Laboratory for Statistical and Translational Genetics, RIKEN Center for Integrative Medical Sciences, Yokohama City, Kanagawa, Japan
| | - Chikashi Terao
- Laboratory for Statistical and Translational Genetics, RIKEN Center for Integrative Medical Sciences, Yokohama City, Kanagawa, Japan
| | - Yoichiro Kamatani
- Laboratory for Statistical and Translational Genetics, RIKEN Center for Integrative Medical Sciences, Yokohama City, Kanagawa, Japan.,Laboratory of Complex Trait Genomics, Graduate School of Frontier Sciences, The University of Tokyo, Tokyo, Japan
| | - Yoshiko Mizukawa
- Department of Dermatology, Kyorin University School of Medicine, Tokyo, Japan
| | - Tetsuo Shiohara
- Department of Dermatology, Kyorin University School of Medicine, Tokyo, Japan
| | - Mikiko Tohyama
- Department of Dermatology, Ehime University Graduate School of Medicine, Ehime, Japan
| | - Hiroaki Azukizawa
- Department of Dermatology, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Michiko Aihara
- Department of Environmental Immuno-Dermatology, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Hiroyuki Nihara
- Department of Dermatology, Faculty of Medicine, Shimane University, Shimane, Japan
| | - Eishin Morita
- Department of Dermatology, Faculty of Medicine, Shimane University, Shimane, Japan
| | - Yoshinori Murakami
- Division of Molecular Pathology, Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Michiaki Kubo
- RIKEN Center for Integrative Medical Sciences, Yokohama City, Kanagawa, Japan
| | - Taisei Mushiroda
- Laboratory for Pharmacogenomics, RIKEN Center for Integrative Medical Sciences, Yokohama City, Kanagawa, Japan
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Li Z, Wang C, Ji S, Jin H, Song G. The Evolution of Population Pharmacokinetic Model of Oral Phenytoin for Early Seizure Prophylaxis Post-Craniotomy. Curr Drug Metab 2019; 20:756-764. [PMID: 31518217 DOI: 10.2174/1389200220666190913115837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2019] [Revised: 08/20/2019] [Accepted: 09/02/2019] [Indexed: 11/22/2022]
Abstract
BACKGROUND This study aimed to re-establish a Population Pharmacokinetic (PPK) model of oral phenytoin to further optimize the individualized medication regimen based on our previous research. METHODS Patients with intracranial malignant tumor requiring craniotomy were prospectively enrolled according to the inclusion criteria. Genotypes of CYP2C9*1 or *3 and CYP2C19*1, *2 or *3 were determined by real time PCR (TaqMan probe) method. Serum concentrations of phenytoin on the 4th and 7th day after oral administration were determined using fluorescence polarization immunoassay. The PPK parameters were estimated using Nonlinear Mixed Effects Models (NONMEM) and internal validation was performed using bootstraps. The predictive performance of the final model was evaluated by Normalized Predictive Distribution Errors (NPDEs) and diagnostic goodness- of-fit plots. RESULTS A total of 390 serum samples were collected from 170 patients in PPK model building group. The population typical values for Vm, Km and the apparent volume of distribution (V) in the final model were 17.5 mg/h, 6.41 mg/L and 54.8 L, respectively. Internal validation by bootstraps showed that the final model was stable and reliable. NPDEs with a normal distribution and a scatterplot with symmetrical distribution showed that the final model had good predictive capability. Individualized dose regimens of additional 40 patients in the external validation group were designed by the present final PPK model. The percentages of patients with serum concentrations within the therapeutic range were 61.53% (24/39) on the 4th day and 94.87% (37/39) on the 7th day, which were higher than the 39.33% (59/150) and 52.10% (87/167) of above 170 patients (P < 0.0001). CONCLUSION The present PPK final model for oral phenytoin may be used to further optimize phenytoin individualized dose regimen to prevent early seizure in patients after brain injury if patient characteristics meet those of the population studied.
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Affiliation(s)
- Zhongdong Li
- Electric Power Teaching Hospital, Capital Medical University, Beijing 100073, China.,Air Force Clinical School, AnHui Medical University, Hefei 230032, China
| | - Chuan Wang
- Air Force Clinical Department, Chinese PLA General Hospital, Beijing 100000, China
| | - Shuangmin Ji
- Center for Drug Evaluation, National Medical Products Administration, Beijing 100022, China.,School of Pharmaceutical Sciences, Peking University, Beijing 100191, China
| | - Hao Jin
- Air Force Clinical School, AnHui Medical University, Hefei 230032, China
| | - Guiqin Song
- Electric Power Teaching Hospital, Capital Medical University, Beijing 100073, China
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Use of a personalized phenytoin dosing approach to manage difficult to control seizures in an infant with a SCN2A mutation. Eur J Clin Pharmacol 2019; 75:737-739. [PMID: 30643928 DOI: 10.1007/s00228-019-02629-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 01/03/2019] [Indexed: 10/27/2022]
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Abstract
OBJECTIVE The purpose of this study is to describe the pharmacokinetics of phenytoin in pediatric patients receiving fosphenytoin. DESIGN Retrospective, population pharmacokinetic analysis. SETTING Emergency department or PICU of a large tertiary care children's hospital. PATIENTS Patients less than 19 years old who received fosphenytoin in the PICU or emergency center for treatment of seizures from January 2011 to June 2017 were included. INTERVENTIONS Population pharmacokinetic analysis was performed with NONMEM v7.3 (Icon Plc, Dublin, Ireland). Simulation was performed to determine optimal loading dose and maintenance dosing regimens. MEASUREMENTS AND MAIN RESULTS A total of 536 patients (55.4% male; median age, 3.4 yr [interquartile range, 0.92-8.5 yr]) met study criteria. Fosphenytoin was administered at median 15.1 mg/kg/dose (interquartile range, 6.3-20.7 mg/kg/dose). Mean serum concentrations of 17.5 ± 7.8 mg/L were at a median 4.2 hours (interquartile range, 2.5-7.8 hr) after a dose. A pharmacokinetic model with two compartments, allometrically scaled fat-free mass on all parameters, and serum creatinine and concomitant phenobarbital use on clearance had the best fit. Simulation demonstrated that a 20 mg/kg loading dose followed by 6 mg/kg/dose every 8 hours had the greatest percentage of concentrations in the 10-20 mg/L range, with reduced doses to achieve therapeutic in patients with reduced kidney function. CONCLUSIONS A loading dose of 20 mg/kg followed by 6 mg/kg/dose every 8 hours based on fat-free mass is a reasonable empiric strategy for attainment and maintenance of therapeutic trough concentrations. Concomitant phenobarbital use may increase clearance of phenytoin and fosphenytoin dose reductions should occur in patients with reduced kidney function.
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Dagenais R, Wilby KJ, Elewa H, Ensom MHH. Impact of Genetic Polymorphisms on Phenytoin Pharmacokinetics and Clinical Outcomes in the Middle East and North Africa Region. Drugs R D 2017; 17:341-361. [PMID: 28748348 PMCID: PMC5629135 DOI: 10.1007/s40268-017-0195-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Genetic polymorphisms are known to influence outcomes with phenytoin yet effects in the Middle East and North Africa region are poorly understood. OBJECTIVES The objective of this systematic review was to evaluate the impact of genetic polymorphisms on phenytoin pharmacokinetics and clinical outcomes in populations originating from the Middle East and North Africa region, and to characterize genotypic and allelic frequencies within the region for genetic polymorphisms assessed. METHODS MEDLINE (1946-3 May, 2017), EMBASE (1974-3 May, 2017), Pharmacogenomics Knowledge Base, and Public Health Genomics Knowledge Base online databases were searched. Studies were included if genotyping and analyses of phenytoin pharmacokinetics were performed in patients of the Middle East and North Africa region. Study quality was assessed using a National Institutes of Health assessment tool. A secondary search identified studies reporting genotypic and allelic frequencies of assessed genetic polymorphisms within the Middle East and North Africa region. RESULTS Five studies met the inclusion criteria. CYP2C9, CYP2C19, and multidrug resistance protein 1 C3435T variants were evaluated. While CYP2C9*2 and *3 variants significantly reduced phenytoin metabolism, the impacts of CYP2C19*2 and *3 variants were unclear. The multidrug resistance protein 1 CC genotype was associated with drug-resistant epilepsy, but reported impacts on phenytoin pharmacokinetics were conflicting. Appreciable variability in minor allele frequencies existed both between and within countries of the Middle East and North Africa region. CONCLUSIONS CYP2C9 decrease-of-function alleles altered phenytoin pharmacokinetics in patients originating from the Middle East and North Africa region. The impacts of CYP2C19 and multidrug resistance protein 1 C3435T variants on phenytoin pharmacokinetic and clinical outcomes are unclear and require further investigation. Future research should focus on the clinical outcomes associated with phenytoin therapy. PROSPERO 2017: CRD42017057850.
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Affiliation(s)
- Renée Dagenais
- Faculty of Pharmaceutical Sciences, Pharmaceutical Sciences Building, University of British Columbia, Vancouver, BC, Canada
| | - Kyle John Wilby
- College of Pharmacy, Qatar University, PO Box 2713, Doha, Qatar.
| | - Hazem Elewa
- College of Pharmacy, Qatar University, PO Box 2713, Doha, Qatar
| | - Mary H H Ensom
- Faculty of Pharmaceutical Sciences, Pharmaceutical Sciences Building, University of British Columbia, Vancouver, BC, Canada
- Department of Pharmacy, Children's and Women's Health Centre of British Columbia, Vancouver, BC, Canada
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11
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Chaudhary N, Kabra M, Gulati S, Gupta YK, Pandey RM, Bhatia BD. Frequencies of CYP2C9 polymorphisms in North Indian population and their association with drug levels in children on phenytoin monotherapy. BMC Pediatr 2016; 16:66. [PMID: 27179628 PMCID: PMC4868001 DOI: 10.1186/s12887-016-0603-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Accepted: 05/11/2016] [Indexed: 12/24/2022] Open
Abstract
Background Phenytoin, mainly metabolized by cytochrome P450 enzyme system, has a narrow therapeutic index and may have adverse effects due to inter-individual variation in the dose requirement and genetic polymorphisms. This cross-sectional study was done to study the prevalence of cytochrome P450 CYP2C9 polymorphisms in Indian epileptic children and to see the effect of polymorphisms on serum levels in epileptic children on phenytoin monotherapy. Methods We studied 89 epileptic children of North Indian population, randomly selected, to see the genotypic and allelic frequency of CYP2C9 and its association with drug levels on phenytoin monotherapy. Analysis was done using STATA 9 Software. The results were analyzed as prevalence at 95 % C.I. (Confidence Interval). The difference in mean phenytoin serum levels between wild and mutant alleles was tested using Student`s T test for independent samples. P value less than 0.05 was considered statistically significant. Results CYP2C9*1, *2 & *3 allelic frequencies were 85.4, 4.5 and 10.1 % respectively. CYP2C9*3 allelic group showed significantly higher serum phenytoin levels compared to the wild variants (P = 0.009). There was no statistically significant difference in the dose received (P = 0.12) and side effects of CYP2C9*2 and CYP2C9*3 genotypes (P = 0.442 and 0.597 respectively) when compared with wild variant. Conclusion CYP2C9*3 is more common than *2 in the present study. All the polymorphisms demonstrated in our study were heterozygous with no homozygosity. Serum phenytoin levels are higher in polymorphic groups (*3) which suggest their poor metabolizing nature. Genotyping may help to avoid toxicity and concentration-dependent adverse effects. Electronic supplementary material The online version of this article (doi:10.1186/s12887-016-0603-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Nagendra Chaudhary
- Department of Pediatrics, All India Institute of Medical Sciences, New Delhi, India. .,Department of Pediatrics, Universal College of Medical Sciences, Bhairahawa, Nepal.
| | - Madhulika Kabra
- Genetic Unit, Department of Pediatrics, All India Institute of Medical Sciences, New Delhi, India
| | - Sheffali Gulati
- Division of Pediatric Neurology, Department of Pediatrics, All India Institute of Medical Sciences, New Delhi, India
| | - Yogendra Kumar Gupta
- Department of Pharmacology, All India Institute of Medical Sciences, New Delhi, India
| | - Ravindra Mohan Pandey
- Department of Biostatistics, All India Institute of Medical Sciences, New Delhi, India
| | - Bal Dev Bhatia
- Department of Pediatrics, Universal College of Medical Sciences, Bhairahawa, Nepal
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Franco V, Perucca E. CYP2C9 polymorphisms and phenytoin metabolism: implications for adverse effects. Expert Opin Drug Metab Toxicol 2015; 11:1269-79. [DOI: 10.1517/17425255.2015.1053463] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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