Pharmacokinetics of verapamil and its metabolite norverapamil from a buccal drug formulation.

Pharmacokinetics of verapamil and its metabolite norverapamil, from buccal drug formulation administered in a dose 20 mg in relation to conventional tablets of verapamil 40 mg, used in medical practice, was determined. Buccal formulation has previously been designed as an alternative form of dosing verapamil. Bioavailability was determined by a crossover method in 12 healthy volunteers. Drug concentration in plasma was determined by means of HPLC with a fluorescence detector. For buccal formulation the average values of C(max) and AUC(0-24 h) for verapamil were much higher than for the reference Staveran tablets and amounted to 51.28 and 320.23 ng/ml h, respectively. However, for norverapamil the corresponding values for buccal formulation were much lower than for a conventional tablet. It has been demonstrated that the proposed buccal verapamil dosing ensures different metabolism of the drug as compared to tablets. Better parameters of bioavailability of verapamil from buccal formulation of twice a smaller dose than that in the tablet, prove that this new drug might be form more effective clinically than the conventional one.