Metabolism of (‐) deprenyl to amphetamine and methamphetamine may be responsible for deprenyl's therapeutic benefit

Abstract

The urinary excretion of some important phenylethylamines, catecholamines, their metabolites, amphetamine, and methamphetamine were measured in parkinsonian patients on Sinemet (L-dopa plus carbidopa, a peripheral dopadecarboxylase inhibitor) and depressed patients after chronic (-) deprenyl treatment. Deprenyl was efficiently metabolized to amphetamine and methamphetamine. It increased the excretion of phenylethylamine and of m- and p-tyramine, and reduced the output of norepinephrine metabolites, but failed to alter the excretion of dopamine-deaminated metabolites. These changes were attributed more to amphetamine and methamphetamine than to inhibition of monoamine oxidase type B. Sinemet treatment alone increased the excretion of dopamine, 3-methoxytyramine, and their respective deaminated metabolites, 3, 4-dihydroxyphenylacetic acid and homovanillic acid. It is concluded that conversion of deprenyl to amphetamine and methamphetamine may contribute to some of the therapeutic benefits of deprenyl.