The disposition of indomethacin in preterm babies.

Limited pharmacokinetic data are available concerning the disposition of indomethacin in preterm infants. Since oral absorption of the drug may be poor or incomplete, the current report provides pharmacokinetic data on 37 premature infants who received indomethacin intravenously. Each of these infants had a hemodynamically significant patent ductus arteriosus. Findings included variable serum indomethacin concentrations from four to 12 hours after a single dose of 0.2 mg/kg. Female preterm infants generally had lower serum drug values at 12 hours and beyond when compared to males. An extrauterine age dependence was found of serum indomethacin levels. Total body clearance, serum half lives and volumes of distribution also bore a direct relationship to extrauterine age. Thus, when indomethacin is administered shortly after birth, one may anticipate a longer duration of action after a single dose and a relatively greater risk of accumulation of the drug when more than one dose is required for treating a duct al patency.