The aim of this study was to investigate the bioavailability of tramadol hydrochloride after oral administration of Tramadol--50 mg capsules, made in Synteza Pharmaceutical-Chemical Company in Poznań. As a reference preparation of Tramadol was used Tramal--50 mg capsules, (Grünenthal, Germany). The preparations were investigated in 20 healthy volunteers, according to a randomised two-way, cross-over design in the fasted state. Blood samples for determination of tramadol plasma concentrations were collected at pre-defined time points up to 24 h following drug administration. A washout period of one week separated both treatment periods. Tramadol plasma concentrations were determined by means of a validated HPLC method (fluorescence detector, verapamil as an internal standard). Values of 1,226.4 ng h/ml (Tramadol) and 1,397.01 ng x h/ml (Tramal) for the parameter AUC(0-infinity) demonstrate a nearly identical extent of drug absorption. Maximum concentrations--Cmax (217.81 ng/ml and 246.0 ng/ml) and time to reach maximum plasma concentration--Tmax (2.14 and 2.31 h) achieved for Tramadol and reference preparation did not differ significantly.
Conclusions: the bioavailability of tramadol hydrochloride after administration of Tramadol is the same as after administration of Tramal, whose clinical efficacy was tested before.