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Determination of Clobazam and Its Major Metabolite N-desmethylclobazam in Human Plasma with High-Performance Liquid Chromatography. ANALYTICA 2021. [DOI: 10.3390/analytica2030007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Clobazam (CLB) is a benzodiazepine that is used in many types of epilepsy. Although therapeutic drug monitoring (TDM) of CLB is not routine, there is evidence that TDM may be of value in conditions where pharmacokinetic alterations are suspected. Therefore, determination of both CLB and its active metabolite concentrations is essential for TDM. Herein, we present a simple and practical method for determination of CLB and N-desmethylclobazam (NDMCLB) in human plasma by high-performance liquid chromatography (HPLC). The drugs were extracted by hexane:dichloromethane (1:1, v/v) from 0.3 mL plasma. The separation was carried out with a C18 reverse phase column using a mobile phase of water:acetonitrile (57:43, v/v) pumped at 0.8 mL/min. The analytes were detected at 228 nm. The method was linear over the concentration range 20–500 ng/mL for CLB and 200–3000 ng/mL for NDMCLB. The intra-day coefficient of variation (CV) was <10% for CLB and <6% for NDMCLB, while the inter-day CV for CLB was <16%. The metabolite inter-day CV was <6%. The accuracy of intra- and inter-day assessments determined for CLB and NDMCLB was within ±10%. This paper describes a rapid, reliable, and simple method for measuring CLB and its metabolite NDMCLB in human plasma. This UV-HPLC procedure offers acceptable precision and accuracy to quantify CLB and its metabolite in human plasma.
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Tolbert D, Larsen F. A Comprehensive Overview of the Clinical Pharmacokinetics of Clobazam. J Clin Pharmacol 2018; 59:7-19. [PMID: 30285275 PMCID: PMC6585772 DOI: 10.1002/jcph.1313] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Accepted: 08/10/2018] [Indexed: 12/22/2022]
Abstract
Clobazam (CLB) is a 1,5‐benzodiazepine that has been widely used as an anxiolytic and antiseizure drug (ASD) since it was first synthesized over 50 years ago. CLB was approved in the United States in 2011 as adjunctive therapy for seizures in patients ≥2 years old with Lennox‐Gastaut syndrome. CLB pharmacokinetics (PK) have been studied in single‐ and multiple‐dose administrations in healthy subjects. Salient features include high bioavailability, linear PK, and negligible effects from coadministration of other ASDs. CLB is highly and extensively absorbed, with little effect from food; time to maximum plasma concentration is 0.5 to 4 hours following the dose. After CLB doses of 20 to 40 mg/day, the volume of distribution is 99 to 120 L, with oral clearance ranging from 1.9 to 2.3 L/h. CLB is lipophilic and distributes throughout the body after oral administration. It is metabolized in the liver by cytochrome P450 (CYP) isoenzymes CYP3A, CYP2C19, and CYP2B6, and its main active metabolite is N‐desmethylclobazam. The half‐life of CLB after a single oral dose ranges from 36 to 42 hours; the half‐life of N‐desmethylclobazam ranges from 59 to 74 hours. The metabolites of CLB are primarily excreted renally. Population PK modeling using data from healthy subjects and patients with Lennox‐Gastaut syndrome indicates that race, sex, age, weight, and renal function do not influence CLB PK. As CLB has been extensively studied since the 1970s, this review is meant to provide a consolidated and comprehensive resource on CLB PK for both prescribers and scientists alike.
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Huddart R, Leeder JS, Altman RB, Klein TE. PharmGKB summary: clobazam pathway, pharmacokinetics. Pharmacogenet Genomics 2018; 28:110-115. [PMID: 29517622 PMCID: PMC5914180 DOI: 10.1097/fpc.0000000000000327] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
| | - J Steven Leeder
- Division of Clinical Pharmacology, Toxicology and Therapeutic Innovation, Children's Mercy Hospital, Kansas City, Missouri, USA
| | - Russ B Altman
- Biomedical Engineering
- Genetics, Stanford University, Stanford, California
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Strand MC, Mørland J, Slørdal L, Riedel B, Innerdal C, Aamo T, Mathisrud G, Vindenes V. Conversion factors for assessment of driving impairment after exposure to multiple benzodiazepines/z-hypnotics or opioids. Forensic Sci Int 2017; 281:29-36. [PMID: 29101905 DOI: 10.1016/j.forsciint.2017.10.022] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2017] [Revised: 09/06/2017] [Accepted: 10/11/2017] [Indexed: 11/18/2022]
Abstract
AIMS Norway has introduced legal concentration limits in blood for 28 non-alcohol drugs in driving under the influence cases. As of 2016 this legislation also regulates the assessment of combined effects of multiple benzodiazepines and opioids. We herein describe the employed methodology for the equivalence tables for concentrations of benzodiazepines/z-hypnotics and opioids implemented in the Norwegian Road Traffic Act. METHODS Legislative limits corresponding to impairment at blood alcohol concentrations (BAC) of 0.02%, 0.05% and 0.12% were established for 15 different benzodiazepines and opioids. This was based on a concept of a linear relationship between blood drug concentration and impairment in drug naïve users. Concentration ratios between these drugs were used to establish conversion factors and calculate net impairment using diazepam and morphine equivalents. RESULTS Conversion factors were established for 14 benzodiazepines/z-hypnotics (alprazolam, bromazepam, clobazam, clonazepam, etizolam, flunitrazepam, lorazepam, nitrazepam, nordiazepam, oxazepam, phenazepam, temazepam, zolpidem and zopiclone) and two opioids (methadone and oxycodone). CONCLUSIONS Conversion factors to calculate diazepam and morphine equivalents for benzodiazepines/z-hypnotics and selected opioids, respectively, have been operative in the Norwegian Road Traffic Act as of February 2016. Calculated equivalents can be applied by the courts to meter out sanctions.
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Affiliation(s)
| | - Jørg Mørland
- Norwegian Institute of Public Health, Division of Health Data and Digitalization, Oslo, Norway.
| | - Lars Slørdal
- Department of Laboratory Medicine, Children's and Women's Health, Norwegian University of Science and Technology, Trondheim, Norway; Department of Clinical Pharmacology, St. Olav University Hospital, Trondheim, Norway.
| | - Bettina Riedel
- University of Bergen, Faculty of Medicine and Dentistry, Department of Clinical Science, Bergen, Norway; Haukeland University Hospital, Laboratory of Clinical Biochemistry, Bergen, Norway.
| | | | - Trond Aamo
- Department of Clinical Pharmacology, St. Olav University Hospital, Trondheim, Norway.
| | - Grete Mathisrud
- Norwegian Ministry of Transport and Communications, Department of Public Roads and Traffic Safety, Oslo, Norway.
| | - Vigdis Vindenes
- Oslo University Hospital, Department of Forensic Medicine, Oslo, Norway; Center of Drug and Addiction Research, Faculty of Medicine, University of Oslo, Norway.
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Tolbert D, Bekersky I, Chu HM, Ette EI. An integrative population pharmacokinetics approach to the characterization of the effect of hepatic impairment on clobazam pharmacokinetics. J Clin Pharmacol 2015; 56:213-22. [PMID: 26139309 DOI: 10.1002/jcph.586] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Accepted: 06/24/2015] [Indexed: 11/10/2022]
Abstract
An integrative population pharmacokinetics (PPK)-based approach was used to characterize the effect of hepatic impairment on clobazam PK and its major metabolite in systemic circulation, N-desmethylclobazam (N-CLB). At therapeutic clobazam dosages, N-CLB plasma concentrations are 3-5 times greater than the parent compound. PK data from clinical trials in patients with Lennox-Gastaut syndrome (LGS; OV-1002 and OV-1012), healthy participants (OV-1016), and participants with and without renal impairment (OV-1032), as well as those from a publication describing the effects of hepatic impairment on clobazam PK, were merged to create the PPK model. Individual patient clobazam PK parameters from the publication were used to generate patient plasma-concentration data. Clobazam PK was linear and the formation of N-CLB was elimination-rate limited. Hepatic impairment did not affect the total apparent clearance of clobazam but may affect the PK of N-CLB. Because the formation of N-CLB is elimination-rate limited and the total apparent clearance of clobazam is unaffected by hepatic impairment, the PPK model suggests that patients with LGS and hepatic impairment may not require clobazam dosage modification.
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Anderson GD, Hakimian S. Pharmacokinetic of antiepileptic drugs in patients with hepatic or renal impairment. Clin Pharmacokinet 2014; 53:29-49. [PMID: 24122696 DOI: 10.1007/s40262-013-0107-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Many factors influence choice of antiepileptic drugs (AEDs), including efficacy of the drug for the indication (epilepsy, neuropathic pain, affective disorder, migraine), tolerability, and toxicity. The first-generation AEDs and some newer AEDs are predominately eliminated by hepatic metabolism. Other recent AEDs are eliminated by renal excretion of unchanged drug or a combination of hepatic metabolism and renal excretion. The effect of renal and hepatic disease on the dosing will depend on the fraction of the AED eliminated by hepatic and/or renal excretion, the metabolic isozymes involved, as well as the extent of protein binding, if therapeutic drug monitoring is used. For drugs that are eliminated by renal excretion, methods of estimating creatinine clearance can be used to determine dose adjustments. For drugs eliminated by hepatic metabolism, there are no specific markers of liver function that can be used to provide guidance in dosage adjustments. Based on studies with probe drugs, the hepatic metabolic enzymes are differentially affected depending on the cause and severity of hepatic disease, which can aid in predicting dose adjustment when clinical data are not available. Several AEDs are also associated with laboratory markers of mild hepatic dysfunction and, rarely, more severe hepatic injury. In contrast, the risk of renal injury from AEDs is generally low. In general, co-morbid hepatic or renal diseases influence the decision for the selection of an AED. For some patients dosing changes to their existing AEDs may be appropriate. For others, a change to another AED may be a better option.
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Clobazam therapeutic drug monitoring: a comprehensive review of the literature with proposals to improve future studies. Ther Drug Monit 2013; 35:30-47. [PMID: 23318278 DOI: 10.1097/ftd.0b013e31827ada88] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
BACKGROUND Clobazam was recently approved for Lennox-Gastaut syndrome in the United States. There is no published review article focused on clobazam therapeutic drug monitoring (TDM) in English. METHODS More than 200 clobazam articles identified by a PubMed search were carefully reviewed for information on clobazam pharmacokinetics. Clobazam is mainly metabolized by a cytochrome P450 (CYP) isoenzyme, CYP3A4, to its active metabolite, N-desmethylclobazam. Then, N-desmethylclobazam is mainly metabolized by CYP2C19 unless the individual has no CYP2C19 activity [poor metabolizer (PM)]. RESULTS Using a mechanistic approach to reinterpret the published findings of steady-state TDM and single-dosing pharmacokinetic studies, 4 different serum clobazam concentration ratios were studied. The available limited steady-state TDM data suggest that the serum N-desmethylclobazam/clobazam ratio can be useful for clinicians, including identifying CYP2C19 PMs (ratio >25 in the absence of inhibitors). There are 3 possible concentration/dose (C/D) ratios. The clobazam C/D ratio has the potential to measure the contribution of CYP3A4 activity to the clearance of clobazam from the body. The N-desmethylclobazam C/D ratio does not seem to be a good measure of clobazam clearance and should be substituted with the total (clobazam + N-desmethylclobazam) C/D ratio. CONCLUSIONS Future clobazam TDM studies need to use trough concentrations after steady state has been reached (>3 weeks in normal individuals and several months in CYP2C19 PMs). These future studies need to explore the potential of clobazam and total C/D ratios. Better studies on the relative potency of N-desmethylclobazam compared with the parent compound are needed to provide weighted total serum concentrations that correct for the possible lower N-desmethylclobazam pharmacodynamic activity. Standardization and more studies of C/D ratios from clobazam and other drugs can be helpful to move TDM forward.
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Johannessen Landmark C, Johannessen SI, Tomson T. Host factors affecting antiepileptic drug delivery-pharmacokinetic variability. Adv Drug Deliv Rev 2012; 64:896-910. [PMID: 22063021 DOI: 10.1016/j.addr.2011.10.003] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Revised: 10/11/2011] [Accepted: 10/14/2011] [Indexed: 01/16/2023]
Abstract
Antiepileptic drugs (AEDs) are the mainstay in the treatment of epilepsy, one of the most common serious chronic neurological disorders. AEDs display extensive pharmacological variability between and within patients, and a major determinant of differences in response to treatment is pharmacokinetic variability. Host factors affecting AED delivery may be defined as the pharmacokinetic characteristics that determine the AED delivery to the site of action, the epileptic focus. Individual differences may occur in absorption, distribution, metabolism and excretion. These differences can be determined by genetic factors including gender and ethnicity, but the pharmacokinetics of AEDs can also be affected by age, specific physiological states in life, such as pregnancy, or pathological conditions including hepatic and renal insufficiency. Pharmacokinetic interactions with other drugs are another important source of variability in response to AEDs. Pharmacokinetic characteristics of the presently available AEDs are discussed in this review as well as their clinical implications.
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Bentué-Ferrer D, Tribut O, Verdier MC, Debruyne D. [Therapeutic drug monitoring of clobazam]. Therapie 2010; 65:225-31. [PMID: 20699075 DOI: 10.2515/therapie/2010028] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2010] [Accepted: 03/11/2010] [Indexed: 11/20/2022]
Abstract
Clobazam is a 1,5 benzodiazepine available in France since 1975, used in add-on with the other anticonvulsant drugs in the treatment of refractory epilepsies of child and adult and for the treatment of anxiety of adult. It is mainly metabolized in desmethylclobazam, or norclobazam, active metabolite, present in a concentration approximately eight times superior to that of the parent drug, but with an activity of the order of 20 to 40% of that of clobazam. Elimination half-life of clobazam is of 18 h while that of norclobazam is from 40 to 50 h. There is a large interindividual variability in the plasma concentrations. Furthermore, clobazam being prescribed in add-on with the other anticonvulsant drugs in resistant epilepsies, concentration-effect relationship is difficult to bring to light, since, in many studies, the patients who did not answer received the highest doses. Adverse reactions are moderated, appearing more often for the highest concentrations; also the phenomenon of tolerance seems more frequent in high concentrations. However, because of the kinetic interactions, a dosage of clobazam and norclobazam can be useful in certain cases. There is no validated therapeutic range, but the usual concentrations are in the range of 100-300 microg/L for the parent drug and about ten times more for the metabolite. The level of proof of the interest of the Therapeutic Drug Monitoring for this molecule is estimated in: rather useless.
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Schlatter C, Egger SS, Tchambaz L, Krähenbühl S. Pharmacokinetic Changes of Psychotropic Drugs in Patients with Liver Disease. Drug Saf 2009; 32:561-78. [DOI: 10.2165/00002018-200932070-00003] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Patsalos PN, Berry DJ, Bourgeois BFD, Cloyd JC, Glauser TA, Johannessen SI, Leppik IE, Tomson T, Perucca E. Antiepileptic drugs--best practice guidelines for therapeutic drug monitoring: a position paper by the subcommission on therapeutic drug monitoring, ILAE Commission on Therapeutic Strategies. Epilepsia 2008; 49:1239-76. [PMID: 18397299 DOI: 10.1111/j.1528-1167.2008.01561.x] [Citation(s) in RCA: 697] [Impact Index Per Article: 43.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Although no randomized studies have demonstrated a positive impact of therapeutic drug monitoring (TDM) on clinical outcome in epilepsy, evidence from nonrandomized studies and everyday clinical experience does indicate that measuring serum concentrations of old and new generation antiepileptic drugs (AEDs) can have a valuable role in guiding patient management provided that concentrations are measured with a clear indication and are interpreted critically, taking into account the whole clinical context. Situations in which AED measurements are most likely to be of benefit include (1) when a person has attained the desired clinical outcome, to establish an individual therapeutic concentration which can be used at subsequent times to assess potential causes for a change in drug response; (2) as an aid in the diagnosis of clinical toxicity; (3) to assess compliance, particularly in patients with uncontrolled seizures or breakthrough seizures; (4) to guide dosage adjustment in situations associated with increased pharmacokinetic variability (e.g., children, the elderly, patients with associated diseases, drug formulation changes); (5) when a potentially important pharmacokinetic change is anticipated (e.g., in pregnancy, or when an interacting drug is added or removed); (6) to guide dose adjustments for AEDs with dose-dependent pharmacokinetics, particularly phenytoin.
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Affiliation(s)
- Philip N Patsalos
- Institute of Neurology/The National Hospital for Neurology and Neurosurgery, London and The Chalfont Centre for Epilepsy, Chalfont St Peter, United Kingdom.
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