Drug interaction by inhibition or induction of cytochrome P450 enzymes leads to serious adverse effects. The aim of the present study is to evaluate the pharmacokinetic changes of nimodipine when co-administered with pantoprazole in Wistar rats. The pharmacokinetic study was performed to evaluate the possible interaction between nimodipine and pantoprazole in wistar rats. Animals were divided into two groups of 18 animals each. Group A was administered with nimodipine while group B was co-administered with nimodipine and pantoprazole. Blood was withdrawn by retro orbital puncture under ether anesthesia at 0, 0.15, 0.25, 0.5, 0.75, 1, 2, 4, 6, 8, 12, 24, 36 hours and the plasma was separated. Felodipine was used as an internal standard and the concentration of nimodipine was estimated using HPLC. In the present study, treatment of rats with nimodipine and pantoprazole resulted in significant increase in Cmax of nimodipine in group B compared to group A. Tmax was found to be same in both groups. There was a significant decrease in volume of distribution while there was a significant increase in the half life on co-administration of pantoprazole compared to nimodipine alone. There was also a significant decrease in clearance of nimodipine in group B compared to A. The interaction of pantoprazole with nimodipine was found to significantly increase the concentration on nimodipine and significantly increase t1/2. The observed interaction may be due to the ability of pantoprazole to inhibit CYP2C19, the CYP enzyme responsible for metabolism of nimodipine.
