Related Experiment Video

Updated: Jun 26, 2026

Seizure Activity Induced by Electroshock in Drosophila Larvae
06:10

Seizure Activity Induced by Electroshock in Drosophila Larvae

Published on: June 6, 2025

Determination of phenobarbitone population clearance values for physically and mentally handicapped Chinese children

E Chan1, K Chan, R Teoh

  • 1Department of Pharmacy, National University of Singapore, Singapore.

Journal of Clinical Pharmacy and Therapeutics
|January 24, 2009
PubMed

Insights

Body weight and concurrent medications significantly impact phenobarbitone clearance in Hong Kong children with epilepsy. This finding may aid in adjusting phenobarbitone dosage for optimal therapeutic concentrations.

Area of Science:

  • Pharmacokinetics
  • Clinical Pharmacology
  • Pediatric Epilepsy

Background:

  • Phenobarbitone is a widely used antiepileptic drug.
  • Understanding population pharmacokinetic parameters is crucial for optimizing drug therapy in children.

Purpose of the Study:

  • To determine phenobarbitone clearance in pediatric epileptic patients of Chinese origin in Hong Kong.
  • To identify factors influencing phenobarbitone population clearance values.

Main Methods:

  • Utilized nonlinear mixed-effects modeling on steady-state phenobarbitone concentration data.
  • Assessed the influence of age, gender, body weight, and concurrent antiepileptic drug use (carbamazepine or phenytoin) on phenobarbitone clearance.

Main Results:

  • Body weight and concurrent medication use were significant determinants of phenobarbitone clearance.
  • Population mean clearance was 0.250 L/day/kg for monotherapy and 0.208 L/day/kg for polytherapy.
  • Interindividual and intraindividual variability differed between monotherapy and polytherapy groups.

Conclusions:

  • Phenobarbitone clearance is influenced by body weight and concomitant antiepileptic drug use.
  • The established correlation between phenobarbitone clearance and body weight can inform dosage adjustments.
  • Achieving target steady-state plasma concentrations may be facilitated by considering these factors.
Abstract

Related Concept Videos

Pharmacokinetics in Pediatric Patients: Drug Metabolism01:24

Pharmacokinetics in Pediatric Patients: Drug Metabolism

In pediatric care, understanding the nuances of hepatic drug metabolism is crucial, as it significantly differs from that of adults. This divergence is primarily due to the developmental stage of drug-metabolizing enzymes, which affects how medications are processed in the body. In neonates, for instance, the activity of Phase I enzymes—critical for the initial breakdown of drugs—is markedly reduced, functioning at just 20–40% of the levels seen in adults. This reduction poses a challenge in...
Pharmacokinetics in Pediatric Patients: Overview and Drug Absorption01:23

Pharmacokinetics in Pediatric Patients: Overview and Drug Absorption

Understanding the physiological differences in the pediatric population is crucial for effective pharmacotherapy. Neonates, infants, and children exhibit significant variations in gastric pH, gastric emptying time, intestinal transit time, and biliary function. These variations profoundly affect oral drug absorption, necessitating a nuanced approach to pediatric dosing.Neonates present with a unique physiological profile, having a gastric pH greater than 4 and faster and more irregular gastric...
Pharmacokinetics in Pediatric Patients: Drug Excretion01:26

Pharmacokinetics in Pediatric Patients: Drug Excretion

In pediatric medicine, understanding the renal function and drug elimination nuances is crucial for administering safe and effective treatments. Newborns, in particular, display markedly slower renal functions than adults, profoundly affecting how drugs are cleared from their bodies. This slower drug clearance requires clinicians to extend the dosing intervals for many medications to prevent drug accumulation and toxicity while ensuring therapeutic efficacy.One key area where these adjustments...
Nonlinear Pharmacokinetics: Dependence of Elimination Half-Life and Dose Clearance01:23

Nonlinear Pharmacokinetics: Dependence of Elimination Half-Life and Dose Clearance

The elimination half-life and drug clearance of drugs following nonlinear kinetics can vary with dosage. The Michaelis-Menten parameters and drug concentration influence these factors. As the dose increases, the elimination half-life tends to lengthen, resulting in a reduction in clearance and a disproportionately larger area under the curve. The total clearance can be derived from the Michaelis-Menten equation for drugs following a one-compartment model.
A study on guinea pigs examined the...
Pharmacokinetics in Pediatric Patients: Drug Distribution01:17

Pharmacokinetics in Pediatric Patients: Drug Distribution

Drug distribution in the pediatric population exhibits unique challenges and considerations due to the physiological differences between children, particularly neonates and infants, and adults. A crucial aspect of pediatric pharmacology is understanding how these differences impact the pharmacokinetics of various drugs, necessitating age-specific dosing strategies to ensure efficacy and safety.Neonates and infants have a higher total body water content, ~75%–90% of their body weight, compared...
Determination of Michaelis Constant and Maximum Elimination Rate01:20

Determination of Michaelis Constant and Maximum Elimination Rate

The Michaelis constant (KM) and the theoretical maximum process rate (Vmax) are vital parameters in the Michaelis-Menten equation, central to many biochemical reactions. They provide essential insights into enzyme kinetics and drug metabolism.
These parameters can be estimated by analyzing plasma concentration data post-drug administration. A notable example of this application is phenytoin, a drug with capacity-limited kinetics. It's recommended that phenytoin should be administered at two...