Renal effects of felodipine in hypertensive patients with reduced renal function

The new calcium antagonist felodipine with a pronounced arteriolar dilating capacity was used to treat 11 patients with severe hypertension resistant to treatment (4 with essential hypertension, 5 with renoparechymatous hypertension, 2 with renovascular hypertension). Mean glomerular filtration rate for 10 patients was 34 +/- 27 ml/min/1.73 m2 body surface area (51Cr-EDTA clearance) before felodipine. One patient was on haemodialysis treatment. Mean arterial blood pressure in the outpatient clinic was 206 +/- 39/119 +/- 18 mm Hg in spite of treatment with 3 or more antihypertensive drugs. All but 2 patients had been given an angiotensin converting-enzyme inhibitor without success. All vasodilating agents were discontinued and the following morning 5 to 10 mg felodipine was given orally. This resulted in a reduction of average supine blood pressure from 190/110 mm Hg to 150/90 mm Hg during the first hour. The antihypertensive effect was unchanged during 6 hours and the drug was subsequently administered twice or three times a day. Mean systolic and diastolic blood pressure after 1 month was 155 +/- 19/91 +/- 12 mm Hg. Eight patients showed a favourable long term response with a mean systolic and diastolic blood pressure of 154 +/- 17/89 +/- 6mm Hg after 6 months. One patient died from his underlying disease after 2 months and 1 patient discontinued treatment because of ankle oedema after 6 weeks. In the long term treated patients with glomerular filtration rates greater than 15 ml/min/1.73m2 all but 1 showed an improved renal function by 26 +/- 19% (n = 5) after initiation of felodipine therapy. In 2 cases with very low glomerular filtration rate (6 to 7 ml/min/1.73m2) the deterioration of renal function continued after felodipine, but at a slower rate. It is concluded that felodipine decreased blood pressure dramatically in patients with severe hypertension where a majority of the cases had been resistant to a previous therapy. The drug appeared safe also in advanced renal insufficiency.