Long-term safety and efficacy comparison of immediate-release and sustained-release oral verapamil in systemic hypertension.

The long-term safety and efficacy of twice-daily sustained-release verapamil were assessed compared to thrice-daily immediate-release verapamil in 25 patients with mild to moderate systemic hypertension. Patients were monitored on immediate-release verapamil (480 mg/day) for 6 months and were then placed on twice-daily sustained-release verapamil for an additional 6 months. Immediate-release verapamil, with and without a diuretic, successfully controlled standing and sitting systolic and diastolic blood pressures (p less than 0.001) compared to pretreatment baseline values. The effects of verapamil on blood pressure were sustained for an additional 6 months when the sustained-release formulation was utilized. Both formulations were well tolerated, with no significant effects on heart rate. In conclusion, verapamil, in both the immediate- and sustained-release formulations, is equally effective in lowering blood pressure for up to 1 year.