ANTIHYPERTENSIVE EFFECT AND TOLERANCE OF DILTIAZEM AND ENALAPRIL - SINGLE DRUG AND COMBINATION REGIMEN

Objectives: Since conversion enzyme inhibitors and calcium inhibitors may have synergic actions, we evaluated the antihypertensive effect and tolerance of prolonged-release diltiazem (300 mg/d) and enalapril (20 mg/d). Methods: A double blind study included 176 patients with mild to moderate hypertension. Diltiazem was given to 89 (44 males, 45 females, mean age 49.91 +/- 10.50 years, mean resting diastolic arterial pressure 103 +/- 5 mmHg) and 87 (49 males, 38 females, mean age 51.37 +/- 12.13 years, mean resting diastolic arterial pressure 103 +/- 5 mmHg) received enalapril. Single drug therapy was given for 6 weeks and then continued for another 8 weeks in responders. At the end of the first 6-week period non-responders were given a combination regimen (diltiazem 300 mg and enalapril 20 mg). Results: After 6 weeks of single drug therapy, 48 patients in the diltiazem group (61.5%) and 53 in the enalapril group (65.4%) had normal blood pressures which remained normal at the end of the trial 8 weeks later in 36 (76%) and 42 (82%) respectively. After 8 weeks of combined regimen 15 of the 24 non-responders (68%) to single drug diltiazem therapy had normal blood pressures as did 18 of the 23 non-responders (78%) to enalapril alone. Tolerance evaluated clinically, biologically and electrocardiographically was comparable to reports in the literature. Conclusion: Delayed prolonged-release diltiazem 300 mg and enalapril 20 mg thus had equivalent antihypertensive effects and were equally well tolerated. Combination therapy increased effectiveness without inducing any additional side effects.