Bleomycin disposition in children with cancer

Area of Science:

• Pharmacology
• Pediatric Oncology
• Clinical Pharmacokinetics

Background:

• Bleomycin is a chemotherapy agent used in treating various cancers.
• Understanding bleomycin pharmacokinetics in children is crucial for optimizing treatment and minimizing toxicity.
• Previous studies have established bleomycin kinetics in adults, but pediatric data are less comprehensive.

Purpose of the Study:

• To determine bleomycin pharmacokinetic parameters in children following intravenous bolus and prolonged infusion.
• To investigate the influence of age and renal function on bleomycin disposition in pediatric patients.
• To compare bleomycin kinetics in children with adult data.

Main Methods:

• Radioimmunoassay was used to measure plasma and urine bleomycin concentrations in 14 children.
• Pharmacokinetic analysis was performed using two-compartment and one-compartment open models for bolus and infusion doses, respectively.
• Covariate analysis explored the impact of age and renal function on clearance and volume of distribution.

Main Results:

• After intravenous bolus, bleomycin exhibited a two-compartment model with a mean terminal half-life (t1/2 beta) of 3.2 ± 0.7 hr.
• Total plasma clearance (CLT) and renal clearance (CLR) were 51.8 ± 6.1 and 33.5 ± 2.4 ml/min/m2, respectively.
• Younger children (<3 yr) eliminated bleomycin faster than older children, and impaired renal function significantly reduced bleomycin clearance.

Conclusions:

• Bleomycin elimination is faster in younger children compared to older children.
• Reduced bleomycin clearance in pediatric patients with impaired renal function can result in elevated plasma concentrations.
• Bleomycin disposition in older children appears similar to that observed in adults.