RELATIVE BIOAVAILABILITY OF DL-OXYFEDRINE-ASTERISK-HCL AFTER SINGLE-DOSE ORAL-ADMINISTRATION OF TABLETS AS COMPARED TO EQUIMOLAR SOLUTIONS

The pharmacokinetics and comparative bioavailability of oxyfedrine aft er single-dose oral administration of oxyfedrine HCl tablets in compa rison to an equimolar aqueous solution of oxyfedrine HCl were investi gated in 12 healthy male subjects. Six of them received 96 mg DL-oxyfe drine HCl as tablets and solution and the remaining 6 subjects receiv ed 16 mg DL-oxyfedrine HCl as tablets and solution in a randomized cr oss-over design. For evaluation of the relative bioavailability of the tablet formulation, the main metabolite norephedrine (expressed as hy drochloride) was analyzed in plasma for all 12 subject. Furthermore, f or determination of the parent drug, samples of whole blood were analy zed for DL-oxyfedrine HCl. Relevant concentrations of the parent drug were found only in the high dosage group. There was no evidence of do se-linearity referring to AUC and C-max of norephedrine between 16-mg and 96-mg doses of DL-oxyfedrine HCl. The relative bioavailability of the tablet formulation after administration of 16 mg DL-oxyfedrine H Cl, based on the metabolite norephedrine HCl was for AUC:85.37% withi n a 90% confidence interval of 69.29-105.17% and for C-max:78.79% with in a 90% confidence interval of 59.19-104.90%. The figures for the 96 mg dose strength were:AUC:107.85%(90.06-129.15%) and for C-max:74.74%( 62.48-89.42%).