Clinical and cardiovascular effects of alpha methyldopa in combination with decarboxylase inhibitors

The peripheral decarboxylase inhibitor carbidopa, given (100 mg/day) for 6 wk in a double-blind trial, lowered supine diastolic pressure of 10 patients with essential hypertension treated with alpha methyldopa by a small (6 mm Hg) but significant (p less than 0.05) amount. Large doses of benserazide (1.5 gm) did not modify the hypotensive effect of 1.0 gm of alpha methyldopa in untreated hypertension but significantly reduced the central nervous side effects of sedation and dry mouth. These studies indicate that extensive peripheral decarboxylation is not necessary for alpha methyldopa to lower blood pressure and would be compatible with the central nervous site of hypotensive action of this drug.