Pharmacokinetics of postoperative intravenous indomethacin in children.

The disposition of indomethacin was studied in children aged one to four years. Indomethacin 0.35 mg/kg was administered as an intravenous infusion during 15 min. Venous blood samples were collected until 24 hr after infusion. Serum indomethacin was determined with gas chromatography. Using a non-linear regression analysis, the individual data were fitted by a two-compartment open mammillary model with central elimination. Calculated pharmacokinetic parameters were (mean +/- SD); alpha half-life 25.2 +/- 11.3 min; beta half-life 366 +/- 295 min; steady-state volume of distribution 0.74 +/- 0.75 l/kg; volume during elimination phase 1.53 +/- 1.27 l/kg; total body clearance 3.2 +/- 1.7 ml/min./kg. Accordingly, with respect to the pharmacokinetics of indomethacin, children seem to mature early, not later than at the age of one year.