STUDIES ON THE BIOAVAILABILITY OF NITRENDIPINE TABLET

The problem of nitrendipine tablets manufactured in China is its low bioavailability. To solve this, a new tablet formulation was developed by using milling method to increase its relative bioavailability. The commercially available conventional tablet A (Nanjing factory) and C (a Hebei factory) and the new tablet formulation D were compared with the reference tablet B (Bayer Company, West Germany)in vitro and in vivo. The determination ofnitrendipine in vivo was carried out by GC-MS. The pharmacokinetic parameters of nitrendipine in vivo were estimated by using the nonlinear least square computer program on the basis of the compartment model (zero order dissolution, first order absorption). The bioavailability of A, C and D relative to B was 31.8%, 72.2% and 138.9% respectively. The new tablet formuiation D is superior to the imported tablet B in both the extent and rate of absorption.