Bioequivalence of Dextromethorphan Hydrobromide Extended Release Suspension

The bioequivalence and pharmacokinetics of domestic dextromethorphan hydrobromide extended release suspension was investigated in 18 healthy man volunteers, according to randomized crossover design. The plasma concentration of dextrophan, the active metabolite of dextromethorphan, was determined by RP HPLC with fluorescence detection. The pharmacokinetic parameters for the single oral dose of 60 mg dextromethorphan hydrobromide extended release suspension were c max 436.8 ± 116.7 and 409.5 ± 113.7 ng/ml ; T max 3.3 ± 1.0 and 3.4 ± 0.8 h ; T 1/2 7.5 ± 2.7 and 7.5 ± 3.1 h ±; AUC 0→ t n 3435± 664.2 and 3269± 626.0 ng·ml -1 ·h , for testing and imported reference formulations, respectively. For the multiple dosing, the degree of fluctuation ( DF ) was (121.9 ± 37.1) % and (133.2±40.6)%, respectively. The results of two one side test showed that the two formulations may be considered as bio equivalent. The relative bioavailability for the test formulation was (105.9±13.8)%.