Does the combination of cilazapril and propranolol lower blood pressure at rest and during exercise more pronouncedly than either of the two components given alone?

The efficacy of three antihypertensive treatments given for 3 weeks each, 2.5 mg cilazapril, a new potent long-acting angiotensin-converting enzyme (ACE) inhibitor, 120 mg propranolol, and the combination of both, were compared in 17 patients suffering from essential hypertension. Blood pressure control (i.e. sitting diastolic blood pressure at rest less than or equal to 90 mm Hg) was achieved in about 40% of the patients by the monocomponents, the combination therapy increased the rate to 80%. An additional blood pressure-lowering effect of the combination was also observed during isometric exercise (handgrip) but not during isotonic exercise (bicycle). At rest and during isometric exercise on cilazapril alone cardiac output rose, total peripheral resistance fell, on propranolol the inverse reactions occurred. On the combination cardiac output and total peripheral resistance decreased. During isotonic exercise propranolol slightly decreased (VO2max fell, lactate concentration went up), cilazapril slightly increased aerobic capacity (VO2max went up and lactate concentration fell) and exercise tolerance. These effects were partially attenuated by the combination. The additional blood pressure-lowering effect of the combination was assumed to be due to the suppression of the renin-angiotensin-aldosterone system (the ACE inhibitor and the betablocker act in a synergistic way), a peripheral vasodilation, and the reduction of sympathetic tone expressed as heart rate reduction and hence a decrease in cardiac output. It is concluded that the combination of an ACE inhibitor and a betablocker seems to exert a good antihypertensive activity not only at rest but also during exercise.