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January 1, 1973

Gastric Acidity and Levodopa in Parkinsonism

Author Affiliations

Washington, DC

JAMA. 1973;223(1):81. doi:10.1001/jama.1973.03220010067031

To the Editor.—  About 20% of patients with Parkinson's disease have a poor therapeutic response to levodopa taken by mouth. It has been suggested that the pH of gastric juice modifies absorption. Rivera-Calimlin and co-workers showed that parkinsonian patients with alkaline gastric juice achieve a peak serum level of levodopa more rapidly,1 and they reported such a patient whose failure to improve when given levodopa was corrected by alkalinization of the stomach contents.2 Conversely, Cotzias has shown that the action of levodopa in mice is enhanced when it is delivered intragastrically with molar concentrations of hydrochloric acid.3We used the azuresin (Diagnex Blue) diagnostic test to test the secretion of gastric hydrochloric acid in 93 consecutive, unselected, parkinsonian patients. Levodopa was given in therapeutic doses and postural stability, bradykinesia, finger dexterity, tremor, and rigidity were each scored at intervals on a 0- to 4-point scale.4 Their