Captopril in treatment-resistant essential and renal hypertension.

Captopril, an angiotensin converting enzyme inhibitor, was used to treat 25 patients with treatment-resistant hypertension of long duration. Seven patients had essential hypertension, 10 renovascular hypertension and 8 renoparenchymatous hypertension. All patients had GFR greater than 25 ml/min/1.73 m3 BSA. The acute blood-pressure-lowering response to the drug was shown to be dependent on the prevailing activity in the renin-angiotensin system. Its long-term effect was not correlated to the activation of the renin-angiotensin system as the mean blood-pressure decrease was not significantly different for high renin and normal renin patients (21 +/- 3% vs. 19 +/- 2%). All patients needed addition of diuretics and betablockers for optimum control. Nine patients have been well controlled for one year and several of them are now approaching two years' treatment. A few adverse effects were observed, including taste disturbances and increased proteinuria. The latter side effect occurred in two patients with decreased renal function and pre-existing proteinuria. Upon reduction of the dose the proteinuria returned to pre-treatment levels within a few months. We conclude that altogether 78% of these patients with treatment-resistant hypertension obtained greatly improved long-term blood-pressure control on treatment including captopril.