Pharmacokinetics of tiaprofenic acid in infants after a single oral dose.

Ten healthy infants (15.2 +/- 10.6 months old, range 6-35) anesthetized for minor surgery were given a single oral dose (3 mg x kg-1) of tiaprofenic acid (TA). Seven venous blood samples and 0-12 h urine were collected. TA concentrations in plasma and urine were measured by HPLC. Within the whole group the mean +/- SD kinetic parameters were: Cmax: 10.55 +/- 3.31 mg x l-1, Tmax: 1.73 +/- 0.87 h, AUC0-1 32.53 +/- 4.42 mg x l-1 x h, AUC0-infinity 35.33 +/- 4.73 mg x l-1 x h, t1/2 1.82 +/- 0.48 h, Cl/F: 0.09 +/- 0.01 l x h-1 x kg-1, VZ/F: 0.23 +/- 0.08 l x kg-1. Renal clearance was 0.030 +/- 0.009 l x h-1 x kg-1. 32% of the TA dose was recovered in urine, 60% of which was conjugated. AUC0-8h increased significantly with age. The TA kinetic parameters were close to those in 3 to 11-year-old children. The present study suggests slight differences in the TA kinetics between infants and adults. However, the lack of an evidenced direct relationship between plasma TA concentration and either efficacy or tolerance suggests that the TA dose regimen in infants may not have to be different from that in adults.