Selegiline for Treating Parkinson’s Disease

Biogenic amine turnover employs the enzymes catechol-O-methyltransferase and monoamine oxidase in neuronal and glial cells. Inhibition of these enzymes elevates biogenic amine levels in the synaptic cleft. Selegiline is a selective, irreversible monoamine oxidase-B inhibitor. Its gastrointestinal absorption is fast, the maximum concentration is reached within 1 h. Main metabolites of selegiline are desmethylselegiline, methamphetamine and L-amphetamine. Symptomatic benefits of selegiline on motor symptoms in patients with Parkinson’s disease are weak. Intervals and severity of off-periods reduce after addition of selegiline, in particular during chronic levodopa intake. Selegiline increases life expectancy in levodopa-treated patients. Selegiline is administered once or twice daily, in 5 mg tablets up to 10 mg, mostly 7.5 mg. Selegiline long-term trials demonstrate, in summary, that combination of selegiline and levodopa may provide a greater clinical benefit and less progression than levodopa alone, even when levodopa without selegiline is taken at substantially higher doses.