Deposition of [H-3]cocaine, [H-3]nicotine, and [H-3]flunitrazepam in mousehair melanosomes after systemic administration

Microautoradiography was employed to show that association of drugs from th e serum directly with forming hair pigment is a primary pathway of depositi on into the hair, After systemic administration of [H-3]flunitrazepam, [H-3 ]nicotine, and [H-3]cocaine, association of all three drugs with melanin in the forming hair was observed within minutes of dosage. Sebum was determin ed to be an insignificant deposition route for all three drugs, Pigmented m ice had significantly higher concentrations of all three drugs than did non pigmented mice. The results provide a better basis for ultimately using hai r for reliable analysis of drug and environmental toxin exposure.