Bioavailability and Pharmacokinetic Parameters of Teraligen® Retard and Teraligen® Valenta Tablets After a Single Administration to Healthy Volunteers

The bioavailability and pharmacokinetic parameters of film-coated Teraligen Retard (TR 20, 40, and 60 mg at doses of 20, 40, and 60 mg, respectively) and immediate-release film-coated Teraligen Valenta tablets (TV 5 mg at a dose of 20 mg) were compared using double blind randomized placebo-controlled investigations involving a single administration to healthy volunteers. The relative bioavailability (ratio of geometric mean 90% CI values) of TR 20, 40, and 60 mg tablets amounted to 80.95% (62.65 – 104.74%), 214.33% (165.64 – 277.34%), and 394.77% (305.08 – 510.83%) for 20, 40, and 60 mg tablets, respectively. An analysis of the dose–concentration relationship gave a linearity coefficient of 0.1902 ng/(mL·mg) for C_max index and 4.6087 (h·ng)/(mL·mg) for AUC_0-t. The results showed that the pharmacokinetic parameters could be considered linearly dose-dependent in the studied range (20 – 60 mg). The delay of drug release from film-coated TR 20, 40 and 60 mg tablets was evaluated by comparing the mean retention time (MRT) of the drug in vivo. The MRT values of TR 20, 40, and 60 mg tablets were 144.18, 157.40, and 156.30%, respectively, and exceeded the MRT of the drug from immediate-release TV tablets. The results led to the conclusion that TR 20, 40, and 60 mg tablets exhibited a prolonged drug-release profile (as compared to that of TV 5 mg tablets) and were characterized by predictable dose-dependent bioavailability.