Effects of administration route on pharmacokinetics of viloxazine in the rabbit

The absorption of viloxazine chlorhydrate was investigated in ten rabbits. Each animal received the drug (15 mg/kg) by three routes: intravenous, gastric and duodenal. Viloxazine plasma concentrations were low when administered by gastric and duodenal routes compared to those after intravenous injection. Concentrations to peak were 1-2 times higher after duodenal than gastric administration. Times to peak were 23.0 +/- 4.7 min after gastric administration and 9.5 +/- 5.4 min after duodenal administration. A better absorption of viloxazine after administration occurred in the duodenum than in the stomach; these results agree with viloxazine pKa = 8.13. The other pharmacokinetic parameters such as half-life, clearance and volume of distribution where the same irregardless of the administration route.