Related Experiment Videos
Clonazepam disposition in pediatric patients
1Department of Pediatrics, Ohio State University and Children's Hospital, Columbus 43205-2696, USA.
Insights
This study measured clonazepam (CZP) and its metabolite levels in pediatric epilepsy patients. Significant variations in CZP metabolism and 7-aminoclonazepam acetylation rates were observed, suggesting potential genetic influences on drug response.
Area of Science:
- Pharmacology
- Clinical Pharmacy
- Pediatric Neurology
Background:
- Clonazepam (CZP) is an anticonvulsant medication used in epilepsy treatment.
- Understanding CZP pharmacokinetics and metabolism is crucial for optimizing therapeutic outcomes in pediatric patients.
Purpose of the Study:
- To determine the pharmacokinetic profiles of clonazepam (CZP) and its metabolites, 7-aminoclonazepam (7ACZP) and 7-acetamidoclonazepam (7AACZP), in pediatric epilepsy patients.
- To investigate the variability in metabolic rates, specifically CZP nitroreduction and 7ACZP acetylation.
Main Methods:
- Plasma concentrations of CZP and its metabolites were measured in 10 pediatric epilepsy patients (2-18 years) during a single dosing interval.
- Pharmacokinetic parameters, including clearance (CL/F) for CZP nitroreduction and 7ACZP acetylation, were calculated.
- Sensitive analytical methods were used to detect and quantify drug and metabolite concentrations.
Main Results:
- Significant inter-individual variability was observed in CZP nitroreduction rates (CL/F: 7-64 ml/h/kg) and 7ACZP acetylation rates (CL/F: 10-85 ml/h/kg).
- 7-acetamidoclonazepam (7AACZP) was not detected (< 5 ng/ml) using the employed methods.
- No correlation was found between patient age or weight and the observed metabolic rates.
Conclusions:
- Metabolic rates for clonazepam (CZP) and its primary metabolite 7-aminoclonazepam (7ACZP) exhibit substantial variability in pediatric epilepsy patients.
- Genetic control of 7ACZP acetylation is known; further research is needed to explore potential genetic influences on CZP nitroreduction.
- Investigating these metabolic differences may help explain variations in clinical responses to CZP among pediatric patients.
Abstract:
Plasma clonazepam (CZP) and its metabolite [7-aminoclonazepam (7ACZP) and 7-acetamidoclonazepam (7AACZP)] concentrations were measured during a single dosing interval in 10 pediatric epilepsy patients (2-18 years, 11-102 kg) who had been receiving CZP therapeutically from 2 weeks to 4 years. These concentrations were used to determine CZP and metabolite pharmacokinetics. With controlled dosing and postdose sample collection times, large variations were observed in calculated CZP nitroreduction rates [clearance (CL/F) ranged from 7 to 64 ml/h/kg] as well as 7ACZP acetylation rates (CL/F from 10 to 85 ml/h/kg). No 7AACZP (i.e., < 5 ng/ml) was detected by the methods used. Acetylation rates are known to be under genetic control. Further studies are needed to determine whether nitroreduction rates are also under genetic control and whether differences in either of these metabolic rates can explain intraindividual differences in clinical responses observed in CZP-treated patients.