PLASMA RENIN ACTIVITY, BLOOD PRESSURE AND SODIUM EXCRETION DURING TREATMENT WITH CLONIDINE

Abstract
Clonidine, 225 mug a day, has been given orally for 3 months to 15 patients with essential hypertension. Mean BP was reduced from 159/107 to 143/87 mmHg. The antihypertensive effect of the drug was dissociated from changes in plasma renin activity (PRA) during clonidine treatment. PRA levels decreased initially in 6 patients with the highest PRA values before treatment, but then increased again. In 6 patients with lower pretreatment PRA levels, PRA rose continuously. Opposite patterns of 24-hour urinary sodium excretion were observed in these arbitrary subgroups. The antihypertensive effect of clonidine in essential hypertension appears to be independent of changes in PRA.