Incorporation of selegiline metabolites into hair after oral selegiline intake.

We have previously shown that melanin in human hair has a great impact on the incorporation of codeine into hair. The present study on 10 subjects was performed to investigate whether or not these findings could also be extrapolated to other therapeutic drugs. We chose selegiline because it metabolizes to two commonly abused central stimulants, methamphetamine and amphetamine. The results would therefore also be of interest when studying the intake of such drugs and their incorporation into human hair. Selegiline and metabolites were determined by gas chromatography-mass spectrometry, total melanin by spectrophotometry, and pyrrole-tricarboxylic acid by high-performance liquid chromatography with ultraviolet detection. Our results show strong positive exponential relationships (y = e(x)) between melanin and the metabolites, which for methamphetamine improved by normalizing for plasma area under the curve. We conclude that the major metabolites of selegiline can be detected in hair up to four weeks after a single oral dose and that the incorporation closely relates to the melanin contents.