Relative Bioavailability of Sustained Release Tablets of Tramadol Hydrochloride

The pharmacokinetics and relative bioavailability of two brands of sustained release tramadol hydrochloride tablets administrated orally by 18 healthy male volunteers were investigated, according to a randomized crossover design. The plasma concentration of tramadol hydrochloride was determined by RP HPLC method with fluorescence detection. The pharmacokinetic parameters for the single oral dose of 100 mg sustained release tramadol hydrochloride tablets were C max 205.0±51.3 and 193.5±44.0 ng/ml; T max 5.6±2.1 and 5.8±2.6 h; t 1/2 7.3±2.6 and 7.3±2.8 h, for tested and reference tablets, respectively. The relative bioavailability for the tested tablets was 97.36±10.01%. For the multiple dosing, the concentration peak trough ratio (PTR) were 1.42±0.17 and 1.44±0.22, the degree of fluctuation (DF) were 36.09±12.78 and 34.37±14.22%, respectively. The results of two one sided t test showed that the tablets of two brands were bioequivalent.