Enprofylline pharmacokinetics in children with asthma.

The pharmacokinetics of intravenous enprofylline has been studied in 8 children with asthma. The mean plasma half-life of enprofylline (1.0 h) was considerably shorter than that previously reported in adults. The half-life determined from log urine excretion rate data was identical to the plasma half-life, so urine excretion could be used as a non-invasive method to study the elimination rate. As in adults, urinary recovery of unchanged drug averaged 89%, and the volume of distribution, Vz, averaged 0.58 l/kg. Clearance was higher in children than in adults when calculated per kg body weight, but not when calculated per m2 body surface area. The dosage of enprofylline in children would be more accurate if calculated in proportion to surface area rather than to body weight. Data agree with published information on creatinine clearance, which, adjusted for body surface area, stays constant from the age of 3 years until early adult life.