Felodipine in hypertensive patients. A dose finding study in patients refractory to beta-blocker monotherapy.

In a double-blind study, 128 patients with essential hypertension, refractory to beta-blocker monotherapy, were randomised to 1 of 4 treatment groups. Felodipine 2.5 mg twice daily, 5mg twice daily, 10mg twice daily or matched placebo twice daily were administered in addition to the beta-blocker for 4 weeks. Mean supine blood pressure before randomisation to treatment was 167/104 +/- 20/7mm Hg. After 4 weeks of treatment, supine blood pressures 2 hours after dose were 161/98 +/- 20/10mm Hg (P), 152/92 +/- 23/8mm Hg (felodipine 2.5mg), 142/87 +/- 18/7mm Hg (felodipine 5mg) and 142/86 +/- 17/7mm Hg (felodipine 10mg). The falls in systolic and diastolic blood pressures were significantly greater for all 3 felodipine groups than for placebo. Blood pressure reductions were less marked 14 hours after dosage: 161/100 +/- 20/9mm Hg (P), 160/97 +/- 24/9mm Hg (felodipine 2.5mg), 153/97 +/- 21/11mm Hg (felodipine 5mg), and 157/94 +/- 19/9mm Hg (felodipine 10mg); but the two higher doses of felodipine produced a significantly greater sustained fall in blood pressure than placebo. There was a correlation between the dose of felodipine and its antihypertensive effect. Standing blood pressures were reduced to the same extent as supine measurements. Heart rate was not significantly affected. Bodyweight did not increase during the study. Side effects of felodipine therapy were minor, and mostly attributable to the vasodilatory properties of the drug. Only 4 patients withdrew because of side effects. It is concluded that felodipine is an effective and well tolerated antihypertensive drug, and that 5mg twice daily is a suitable starting dose in hypertensive patients refractory to beta-blocker monotherapy. It may be necessary to increase this dose to 10mg twice daily in selected patients.