Multicenter evaluation of the safety and efficacy of isradipine in hypertension. The Italian-Belgian Isradipine Study Group.

One hundred seventy-eight patients, aged 30 to 85, with mild-to-moderate hypertension entered a multicenter double-blind, randomized, between-patient comparison of isradipine (0.5, 1.25, or 2.5 mg twice daily) and placebo. Patients were assessed after three weeks of placebo treatment (for baseline) and after two and five weeks of active therapy. Despite a marked placebo effect, isradipine at 1.25 mg and 2.5 mg twice daily reduced blood pressure to a significantly lower level. The lowest blood pressures were recorded at four hours post-dose, and the residual antihypertensive effect at 12 hours was between 70 and 79 percent of the four-hour measurements. Isradipine did not produce more laboratory, electrocardiographic, or clinical abnormalities, or adverse events than did placebo. It is concluded that isradipine in doses of 1.25 mg and 2.5 mg twice daily is effective and well tolerated in the treatment of mild-to-moderate hypertension.