A COMPARISON OF THE EFFICACY AND TOLERABILITY OF ONCE-DAILY CONTROLLED-RELEASE DILTIAZEM WITH TWICE-DAILY NIFEDIPINE-RETARD IN PATIENTS WITH ESSENTIAL-HYPERTENSION

Two hundred and forty-six patients with mild-to-moderate essential hypertension were random ly assigned to receive in double-blind, double-dummy fashion either once-daily controlled release (CR) diltiazem (ADIZEM-XL capsules, Napp Laboratories, Cambridge) or twice-daily nifedipine retard (R). After a 4-6 week placebo run-in, 193 eligible patients were titrated on either CR-diltiazem from 120-300mg/day or nifedipine-R from 20-80mg/day to achieve target diastolic blood pressure (DBP). The patients then entered a two-week assessment during which they remained on their treatment. Sixty-live responding patients on CR-diltiazem were recruited into a four-month follow-up study to evaluate long-term safety. In the comparative study, CR-diltiazem and nifedipine-R produced a similar and significant reduction in DBP from baseline. There was a higher incidence of flushing of the legs in the nifedipine-R group but no other differences in side effects. Significantly more patients in the nifedipine-R group withdrew due to side effects than in the CR-diltiazem group. Once on a stable dose of CR-diltiazem, 69% of patients continuing in the follow-up study maintained target DBP at the end of four months. A similar incidence of side effects to those reported in the comparative study was seen. The HDL cholesterol levels were significantly increased following long-term treatment. It was concluded that once-daily CR-diltiazem is as effective in controlling essential hypertension as twice-daily nifedipine-R and results in fewer withdrawals due to side effects. Additionally, it is safe and effective for long-term treatment.