Single dose pharmacokinetics of pleconaril in neonates. Pediatric Pharmacology Research Unit Network.

BACKGROUND: Pleconaril is an orally active, broad spectrum antipicornaviral agent with activity against nonpolio enteroviruses. Pleconaril phamacokinetics was evaluated in 16 neonates (16.4 +/- 8.7 days postnatal age) with suspected enteroviral infection.

METHODS: Pleconaril (5 or 7.5 mg/kg) was administered orally to study subjects and plasma pleconaril concentrations quantified from serial blood samples obtained during 24 h after a single oral dose by gas chromatography with electrochemical detection. Pharmacokinetic parameter estimates were determined by noncompartmental methods and compared between doses and with similar data obtained from a previous study of pleconaril disposition in children (n = 18, 2 to 12 years).

RESULTS: Pleconaril was well-tolerated in all neonates without discernible adverse events. Comparison between the 5.0- and 7.5-mg/kg doses revealed no significant differences in peak plasma concentration (Cmax 686.7 vs. 617.1 ng/ml), elimination half-life (t 1/2; 4.6 vs. 6.6 h), area under the plasma concentration vs. time curve (AUC; 5162.6 vs. 5523.9 ng/ml/h), apparent steady state volume of distribution (V(dss)/F; 9.3 vs. 17.1 liters/ kg) and apparent oral clearance (Cl/F; 1.3 vs. 1.7 liters/h/kg). In addition, no correlation was observed between postconceptional age and AUC, V(dss)/F, t 1/2 or Cl/F for pleconaril. Comparison of pleconaril pharmacokinetics between neonates and children suggested a significant difference in V(dss)/F (9.3 vs. 4.7 liters/kg), dose-normalized Cmax, (686.7 vs. 1272.5 ng(ml) and AUC (5125.6 vs. 8131.2 ng/ml/h). In contrast, the mean elimination t 1/2 between neonates and children was not appreciably different.

CONCLUSIONS: The apparent age-dependent differences in the pharmacokinetics of pleconaril may in part be related to increased bioavailability of the drug in older children and adults than in neonates. Our data appear to support the use of a 5.0-mg/kg dose given every 8 to 12 h in future studies of pleconaril in neonatal patients with enteroviral infection.