Studies on the Metabolism and Excretion of L-3, 4-Dihydroxyphenylalanine (L-DOPA) in Human Beings by Gas Chromatography

Abstract

One gram of L-DOPA was administered orally to the patients with Parkinson's disease and normal persons. Plasma DOPA and catecholamines, urinary DOPA, catecholamines and aromatic acids were determined by gas chromatography both before and after acid hydrolysis. DOPA and dopamine conjugate were detected in the plasma soon after the administration, while large personal deviations were observed both in their concentration and time courses. During 24 hr, 0.53%, 4.24%, 32.0%, and 25.9% in average of the administered L-DOPA were excreted in urine as DOPA, dopamine, DOPAC and HVA respectively in a free and conjugated form.