Pharmacokinetics and relative bioavailability of sustained-release nitrendipine capsules in healthy dogs

Objective To study the pharmacokinetics and relative bioavailability of the sustained-release nitrendipine capsules in healthy dogs.Methods Following oral administration of a single dose of the sustained-release nitrendipine capsules (test formulation) and conventional tablets (reference formulation) to each of the 6 healthy dogs in a randomized crossover design,the plasma levels of the active drugs at different time points were determined by HPLC and the plasma concentration-time curves of these formulations were obtained.The pharmacokinetic parameters as well as the relative bioavailability were analyzed.Results The t max values of the test formulation and reference formulation are(6.17±1.60) and (1.46±0.51)h,the c max values are (343.8±122.6) and (456.5±107.4)nmol/L, and the AUC 0～t are ( 1 930.12± 1 005.106) and ( 1 790.8±942.8)nmol·h/L,respectively.The relative bioavailability of the test formulation was found to be (110.59±23.60)% compared with the reference formulation.The results of the variance analysis show that there is no significant difference between the test and reference formulation in periods and formulations (P0.05),but in subjects.The 90% confidence interval of AUC 0～t of the test formulation is 88.54%～131.93% compared with the reference formulation.Conclusions Compared with the conventional tablets,the sustained-release nitrendipine capsules have longer action time in dogs and similar relative bioavailability.