PHARMACOKINETICS AND BIOEQUIVALENCE OF THE MAIN METABOLITES OF SELEGILINE - DESMETHYLSELEGILINE, METHAMPHETAMINE AND AMPHETAMINE AFTER ORAL-ADMINISTRATION OF SELEGILINE

A bioavailability study of 2 different selegiline preparations were co nducted in 20 healthy volunteers to test the bioequivalence. Almost no bioavailability study of selegiline has been published. As plasma lev els of selegiline are very low and the elimination half-life is very s hort being about 9 minutes, therefore, a very sensitive and selective method for determining the 3 main metabolites desmethylselegiline (DMS ), methamphetamine (MA) and amphetamine (A) was developed. After appli cation of a single oral dose of 5 mg selegiline the C-max values of DM S reached 5 - 6 ng/ml, of MA 6 - 7 ng/ml and of A about 2 ng/ml. The A UC(infinity) values were with DMS about 11 ng/ml x h +/- 4,5, with MA about 130 ng/ml x h +/- 50 and with A about 50 ng/ml x h +/- 15. The 9 0% confidence interval was with logarithmic transformed AUC(infinity) values 92 - 107% with DMS, 89 - 107% with MA, and 84 - 104% with A. Th e logarithmic transformed C-max values showed a 90% confidence interva l of 92 - 127% with DMS, 91 - 101% with MA, and 90 - 103% with A. All relevant pharmacokinetic parameters showed bioequivalence with all 3 m etabolites (DMS, MA, and A).