Negligible pharmacokinetic interaction between oral DA-8159, a new erectogenic, and amlodipine in rats

Abstract

A pharmacokinetic interaction between oral DA-8159 and amlodipine was evaluated in male Sprague-Dawley rats. In rats pretreated with troleandomycin (a main inhibitor of CYP3A1/2 in rats), the AUC(0-6 h) of amlodipine was significantly greater than the controls (34.5+/-6.01 compared with 28.0+/-4.70 microg min/ml), indicating that amlodipine is metabolized via CYP3A1/2 in rats. It was reported that the metabolism of DA-8159 and the formation of DA-8164 (a metabolite of DA-8159) were mainly mediated via CYP3A1/2 in rats, and amlodipine significantly inhibited the CYP3A2 in rats. Therefore, a pharmacokinetic interaction between the two drugs could be expected. However, after oral administration of DA-8159 at a dose of 30 mg/kg with or without oral amlodipine at a dose of 5 mg/kg to rats, the pharmacokinetic parameters of DA-8159 and DA-8164 were not significantly different between the two groups of rats. Similar results were also obtained from amlodipine between with and without DA-8159. The above data indicated that the pharmacokinetic interaction between oral DA-8159 and amlodipine was almost negligible in rats.