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Cimetidine pharmacokinetics and dosage requirements in children
Insights
Children eliminate cimetidine faster than adults due to increased renal clearance. This study suggests a cimetidine dosage of 30 mg/kg daily for pediatric patients.
Area of Science:
- Pharmacology
- Pediatric Medicine
- Clinical Pharmacy
Background:
- Cimetidine is a widely used medication.
- Understanding drug pharmacokinetics in children is crucial for safe and effective dosing.
- Previous studies have indicated potential differences in cimetidine metabolism between pediatric and adult populations.
Purpose of the Study:
- To investigate the pharmacokinetics of cimetidine in children.
- To compare cimetidine clearance, volume of distribution, and half-life in children versus adults.
- To determine an appropriate cimetidine dosage regimen for pediatric patients.
Main Methods:
- Oral and intravenous administration of cimetidine (10 mg/kg) to pediatric subjects.
- Pharmacokinetic parameter analysis including total body clearance, volume of distribution, and elimination half-life.
- Comparison of pediatric data with existing adult pharmacokinetic data.
Main Results:
- Children exhibited significantly higher total body clearance (11.6 ml/min/kg) and a larger apparent volume of distribution (1.24 L/kg) compared to adults.
- The elimination half-life of cimetidine was shorter in children (83 min) than in adults (122 min).
- Renal clearance constituted 70% of total body clearance in children, more than double that of adults, with a negative correlation between age and renal clearance.
Conclusions:
- Children demonstrate significantly increased cimetidine elimination compared to adults, primarily driven by enhanced renal tubular secretion.
- A recommended cimetidine dosage regimen for children is approximately 30 mg/kg per day, divided into three to four doses.
- Further research into the specific mechanisms of enhanced renal transport in pediatric populations is warranted.
Abstract:
The pharmacokinetics of cimetidine (10 mg/kg) were investigated in 11 children following an oral dose and in 9 children following an intravenous dose. The children ranged in age from 4-13 years and were undergoing radiology for upper gastrointestinal tract pain. Compared with a group of adults, the children had a higher total body clearance (11.6 +/- 3.4 versus 7.0 +/- 2.5 ml/min per kg; P less than 0.005), a larger apparent volume of distribution (1.24 +/- 0.40 versus 0.80 +/- 0.24 l/kg; P less than 0.005) and a shorter elimination half-life (83 +/- 26 versus 122 +/- 16 min; P less than 0.001) of cimetidine. Renal clearance in children comprised 70% of total body clearance, more than double that of adults (9.0 +/- 1.9 versus 4.2 +/- 2.1 ml/min per kg; P less than 0.001). The area under the cimetidine plasma concentration: time curve after the oral dose was on average 42% in children compared with adults. The mechanism for the increased elimination of cimetidine in children is suggested to be an increase in the renal tubular secretory transport of cimetidine in the kidney. A statistically significant negative correlation was observed between age and cimetidine renal clearance. A cimetidine dosage regimen of approximately 30 mg/kg per day in three to four divided doses would be an appropriate dose in children.