The antihypertensive efficacy and tolerability of the new calcium antagonist isradipine was assessed in 86 hypertensive patients who had pretreatment diastolic blood pressures (DBP) ± 105 mm Hg and who were randomly allocated to a double-blind comparison of three different dosage regimens: 1.25 mg, 2.5 mg, and 5 mg b.i.d., and placebo. A 2-week run-in period was followed by a 4-week course of treatment. Isradipine reduced systolic and diastolic blood pressures dose-dependently: the normalization rate (DBP ± 90 mm Hg) was 5% with placebo and 29, 55, and 64%, with isradipine 1.25, 2.5, and 5 mg b.i.d., respectively. The proportion of patients experiencing at least a 10 mm Hg reduction in sitting DBP was 29, 67, 86, and 91%, respectively. All three dosages proved to he significantly effective compared to placebo. Neither heart rate nor blood pressure regulation in orthostasis were influenced. The main side effects were headache, dizziness, and flushing: isradipine 1.25 and 2.5 mg b.i.d. were well tolerated (not significantly different from placebo). In conclusion, isradipine 2.5 mg h.i.d. appears to he the potential dose of first choice, exhibiting a favorable benefit-risk profile.
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