Acute and chronic effects of spirapril, alone or in combination with isradipine on kidney function and blood pressure in patients with reduced kidneyfunction and hypertension

In the present study we investigated the effect of a single dose, and 3 mon ths of treatment with spirapril on kidney function, renin-angiotensin syste m, renal handling of sodium and blood pressure, in patients with reduced ki dney function (serum creatinine 1.5-3 mg%) and hypertension. A single dose of 6 mg spirapril given at the beginning of the study did not affect glomer ular filtration rate (GFR), renal plasma flow (RPF), angiotensin converting enzyme (ACE) activity, plasma renin activity (PRA) or renal handling of so dium. When the single dose of spirapril was given after 3 months of treatme nt with this agent, renal hemodynamics and PRA did not change. ACE activity , which was depressed by the previous spirapril treatment, decreased furthe r (from 9.5 +/- 3.1 to 1.4 +/- 1.0 nmol/ml/min), (p < 0.05). Administration of 6 mg spirapril o.d. for 3 months did not have any effect on GFR or RPF. Serum ACE activity decreased from 92.1 +/- 8.0 to 5.1 +/- 2.6 nmol/ml/min (p < 0.05) and PRA increased from 1.4 +/- 1.2 to 4.1 +/- 3.6 ng/ml/min (p < 0.05). Plasma aldosterone did not change. Similar results were obtained wh en spirapril was combined with 5 mg isradipine in the initial and final sin gle dose, or in the 3 months' treatment (5 mg o.d.). Blood pressure was nor malized in 38% of the patients who received spirapril and in 71% of the pat ients who received spirapril and isradipine. Thus, (a) treatment with spira pril in patients with mild to moderate chronic renal insufficiency was not associated with deleterious effects on kidney function; (b) spirapril in a dose of 6 mg alone or in combination with 5 mg isradipine is effective in r educing blood pressure in hypertensive patients with reduced kidney functio n.