Imidapril hydrochloride in essential hypertension: a double-blind comparative study using enalapril maleate as a control

OBJECTIVE: To assess the value of using imidapril hydrochloride (ACE/TA-6366), a long-acting angiotensin converting enzyme (ACE) inhibitor developed in Japan, to treat patients with essential hypertension. PATIENTS AND METHODS: A double-blind, comparative, phase III study was carried out using enalapril maleate as a control, with a 4-week observation period and a 12-week treatment period. Both drugs were started at a dose of 5 mg once a day, increasing to 10 mg in patients whose antihypertensive response was insufficient after 4 weeks. The study included 231 outpatients aged 30-74 years; of these, 108 in the imidapril group and 115 in the enalapril group were assessed. There were no differences in background factors between groups. RESULTS: An adequate antihypertensive effect was observed in 71.3% (77/108) in the imidapril group in in 66.1% (76/115) in the enalapril group, with no significant difference between groups. The pulse rate was unchanged in both groups. The drug had no adverse effects in 86.1% (93/108) of the imidapril group and 79.1% (91/115) of the enalapril group, with no significant difference between groups. Adverse drug effects were observed din 5.6% (6/108) of the imidapril group and 12.2% (14/115) of the enalapril group. Cough was the most frequent side effect, reported in 0.9% (1/108) of the imidapril group and 7.0% (8/115) of the enalapril group. Other side effects were reported in 4.6% (5/108) of the imidapril group and 5.2% (6/115) of the enalapril group. Abnormal laboratory values were observed in 3.7% (4/108) of the imidapril group and 0.9% (1/115) of the enalapril group. CONCLUSIONS: Imidapril showed excellent clinical efficacy and safety compared to enalapril. The low incidence of cough is of particular interest.