Low blood pressure is frequent in the akinetic form of Parkinson's disease. A low renin activity in plasma as well as a low rate of aldosterone secretion is demonstrated in these patients. Renin activity in the plasma is further decreased by treatment with L-dihy-droxyphenylalanine, thus partially accouinting for the hypotensive episodes seen with this form of therapy.

The authors report their experience over a 14 month period in the treatment of 20 parkinsonian patients with the combination of levodopa and an inhibitor of peripheral dopa decarboxylase, Ro 4‐4602. The results obtained are comparable to those previously reported from the same center with levodopa alone and, in fact, appear to offer distinct advantages. The average daily dose of levodopa required for satisfactory results (after 3 months of treatment) was reduced from 4.S Gm. of levodopa alone to SOD mg. on the combination. The maximum daily dose of Ro 4‐4602 recommended to obtain this effect is 200 mg.