Thirteen patients were entered into a protocol to assess the safety and efficacy of
enalapril (
MK 421), 5 to 20 mg b.i.d., and
hydrochlorothiazide, 50 to 100 mg daily, for the treatment of
renovascular hypertension. Specifically monitored were the effects of
therapy on blood pressure and pulse, renal function, and the
renin-
angiotensin-
aldosterone axis.
Enalapril and
hydrochlorothiazide therapy produced excellent control of blood pressure with no adverse side effects. After approximately 8 weeks of
therapy, renal vascular resistance was decreased and no adverse effects on glomerular filtration rate or renal blood flow were noted, except in one patient with a functional unilateral stenotic kidney. Patients receiving
enalapril and
hydrochlorothiazide showed stimulation of plasma
renin activity and suppression of plasma
angiotensin II, although the initial degree of suppression was not sustained in all patients during prolonged
therapy. Although plasma
aldosterone concentration was initially suppressed, the degree of suppression was not sustained. Nine patients have been followed for an additional 6 months; none have experienced further progression of renal disease, as assessed by repeated measurements of glomerular filtration and effective renal plasma flow. These results suggest that combined
enalapril and
hydrochlorothiazide therapy is safe and effective in the medical management of
renovascular hypertension and that blood pressure control may be achieved in the absence of sustained interruption of the renin-angiotensin-aldosterone system.