Seligiline

(Eldepryl, Deprenyl)
Seligiline is an antidepressant originally used to treat Parkinson's disease. It also appears to boost libido and fend off aging. Experiments with the usual mice and rats resulted in a life span increase of over 30% and copulation like there was no tomorrow.
A dose of 5 milligrams taken twice a week will yield few side effects, if any, and anecdotal evidence suggests definite aphrodisiac results.