Selegiline has an oral bioavailability of about 10%, which increases when ingested together with a fatty meal, as the molecule is fat soluble. Selegiline and its metabolites bind extensively to plasma proteins (at a rate of 94%). They cross the blood–brain barrier and enter the brain, where they most concentrated at the thalamus, basal ganglia, midbrain, and cingulate gyrus.
Selegiline is mostly metabolized in the intestines and liver; it and its metabolites are excreted in the urine.
Buccal administration of selegiline results in 5-fold higher bioavailability, more reproducible blood concentration, and produces fewer amphetamine metabolites than the oral tablet form.