Hemodynamic and renal function in essential hypertension during treatment with enalapril.

Enalapril (at a mean dose of 25 mg), a potent, long-acting angiotensin converting enzyme inhibitor, was prescribed in combination with hydrochlorothiazide (at a mean dose of 64 mg) for 96 weeks in 11 patients with essential hypertension who had pretreatment (placebo) glomerular filtration rates of less than 80 ml/minute/1.73 m2. Blood pressure was well controlled. After 56 weeks of therapy, glomerular filtration rate (assessed by inulin clearance) increased 55 percent and effective renal plasma flow (assessed by para-amino-hippurate clearance) increased by 32 percent; these increases were sustained through the 96 weeks of therapy. Furthermore, gains in renal function were sustained without adversely affecting 24-hour urinary protein excretion, sodium excretion, or body fluid composition. These results suggest that enalapril, in combination with hydrochlorothiazide, has the pharmacologic capability to favorably modify a primary pathophysiologic characteristic of essential hypertension by decreasing renal vascular and mesangial tone.