Relative bioavailability of tramadol hydrochloride tablets in healthy volunteers

Aim: To study the pharmacokinetics and bioavailability of tramadol hydrochloride tablets in healthy volunteers. Methods: Single oral doses of the standard formulation and the tested formulation were respectively given to 18 volunteers in randomized cross-over test. The tramadol concentrations in plasma were determined by HPLC. Results: The concentration-time curves of two formulations fitted to one-compartment open model. The C max was (410.0±71.1) μg·L -1 and (427.0±57.1) μg·L -1; T max was (2.20±0.49) h and (2.20±0.55) h; T 1/2ke were (7.13±0.83) h and (7.08±0.74) h; AUCt 0 were (4 376±855) μg·h·L -1 and (4 514±1 068) μg·h·L -1; AUC∞ 0 were (5 184± 1 112) μg·h·L -1 and (5 241±1 330) μg·h·L -1,respectively. The pharmacokinetic parameters showed no significant difference between the two formulations(P0.05).The relative bioavailability was (98.94±16.04)% of tested formulation. Conclusion: It is suggested that the two formulations be bioequivalent.