Antihypertensive effects of captopril and saralasin in essential and renal hypertension.

The antihypertensive effect of captopril and its mechanism of action were studied in patients with essential and renal hypertension. In mild essential hypertension (n = 12), during monotherapy with captopril (50 to 450 mg, 4 to 12 weeks) blood pressure was normalized in seven, improved in two and remained unchanged in three patients, plasma levels of active and acid-activatable inactive renin significantly increased and angiotensin II decreased, whereas no consistent changes in urinary kallikrein excretion occurred. In severe renal (n = 14) and essential (n = 9) hypertension, blood pressure was normalized in eight (seven with renal hypertension), improved in seven and unchanged in eight patients, when captopril (50 to 450 mg, 3 to 15 months) was added to the antihypertensive medication. In one patient with stenosis in a transplanted renal artery reversible renal failure occurred during captopril therapy possibly because of a steep initial decrease in blood pressure, although a toxic effect of the drug cannot be excluded. In another series of 12 renal and 8 essential hypertensive patients, a significant correlation between the acute effect of captopril (within 90 minutes) an saralasin on blood pressure was demonstrated (r=0.71, p less than 0.001). The change in blood pressure after either drug was significantly related to the initial plasma renin concentration. In conclusion, captopril seems to be an effective antihypertensive agent in essential and renal hypertension. Renal function should be monitored during captopril therapy. Our studies suggest that captopril decreases blood pressure by inhibiting the vasopressor action of the renin-angiotensin system.