Comparative Evaluation of the Antihypertensive Efficacy of Once-Daily Sustained-Release Isradipine and Lacidipine Using 24-hour Ambulatory Blood-Pressure Monitoring

In this single-blind crossover study the antihypertensive efficacies of two dihydropyridine calcium antagonists, sustained-release isradipine and lacidipine, were compared using clinic and ambulatory blood-pressure measurements. After a 2-week placebo wash-out, 34 patients (19 men, 15 women, mean age 49 years) with mild to moderate hypertension (diastolic blood pressure range 95 – 110 mmHg) were treated with 5 mg sustained-release isradipine for 4 weeks and 4 mg lacidipine for 4 weeks in a random order. Medications were taken once daily at 08.00 h. Clinic and ambulatory blood pressures were recorded at the end of each placebo or treatment period. Two patients stopped isradipine and six lacidipine because of severe adverse effects. Clinic systolic and diastolic blood pressures decreased by an average of 17/14 mmHg with isradipine and 17/13 mmHg with lacidipine, compared with placebo (P < 0.01 in both cases), without a change in heart rate. Mean ambulatory 24-h and daytime systolic and diastolic blood pressure were significantly reduced by sustained-release isradipine and lacidipine (P < 0.05 and P < 0.01, respectively). At night systolic blood pressure fell compared with placebo (P < 0.05 with both drugs) whereas the reduction in diastolic blood pressure was not statistically significant. Mean 24-h heart rate remained unchanged. Blood-pressure variability did not differ significantly between the two drugs or between either drug and the placebo. The antihypertensive effects of sustained-release isradipine and lacidipine were similar, but the tolerability of isradipine appears to be greater since it caused fewer withdrawals.