Abstract: AIM: To study the bioavailability of the lipophilic benfotiamine as compared to a water-soluble thiamine hydrochloride after oral administration.METHODS: A randomized, crossover study involving 20 healthy male volunteers was carried. Each subject was given 300 mg benfotiamine or 220 mg thiamine hydrochloride. Blood samples were collected at different times and 24 h urine samples were collected after administration. The concentrations of thiamine and thiamine diphosphat in plasma or erythrocyte were determined by HPLC-Flu.The main pharmacokinetic parameters were calculated using WinNonlin program and the mean excretion rate of hippuric acid in urine was also evaluated.RESULTS: The main pharmacokinetic parameters of thiamine in plasma after taking benfotiamine and thiamine hydrochloride were as follows: t_1/2 were (2.5±0.2) and (2.0±0.8) h, respectively; AUC_0-24 were (1763.1±432.7) and (182.0±93.8) μg·h·L^-1, respectively; AUC_0-∞ were (1837.3±466.5) and (195.8±96.6) μg·h·L^-1, respectively; C_max were (568.3±122.0) and (70.5±46.2) μg/L, respectively; CL/F were (172.3±39.2)and (1831.7±705.0) L/h, respectively; V_d/F were (627.9±131.8) and (5419.1±3586.6)L, respectively. The AUC_0-24 of thiamine diphosphat in erythrocyte after taking benfotiamine and thiamine hydrochloride was (3212.4±740.7) and (881.8±316.2) μg·h·L^-1, respectively. In comparison with thiamine hydrochloride, the relative bioavailability of thiamine and thiamine diphosphat in benfotiamine were (1147.3±490.3)% and (392.1±114.8)%, respectively. The excretion rate of hippuric acid in urine in 4 h after taking benfotiamine was significantly accelerated than that after taking thiamine hydrochloride.CONCLUSION: Benfotiamine is absorbed quickly, and has better bioavailability than thiamine hydrochloride. It can be transformed to thiamine in 4 h after administration.

Key words: Benfotiamine, Thiamine, Thiamine diphosphat, Bioavailability