Urinary excretion kinetics of methylamphetamine in man

The urinary excretion of methylamphetamine and its metabolite, amphetamine, was studied after oral administration of (+)- and (–)-methylamphetamine hydrochloride to three male subjects. Fluctuations in the excretion rate of both amines occurred and were associated with changes in urinary pH. The fluctuations were abolished when the urine was maintained either acid or alkaline, by administration of ammonium chloride and sodium bicarbonate respectively. The total amount of both amines excreted was lower under alkaline than acid urine conditions. N-Demethylation of methylamphetamine was small, but greater for the (+)- than the (–)-isomer.