Does combination therapy with a calcium channel blocker and an ACE inhibitor have additive effects on blood pressure reduction

Reports in the medical literature have suggested that the effects on blood pressure (BP) of calcium channel blockers (CCBs) and angiotensin-converting enzyme (ACE) inhibitors are additive. Most reports have provided neither a definition of 'additive' nor the necessary information to determine whether the effects are additive. In this review of the medical literature, the effects of combination therapy were defined as additive if the sum of the mean reductions in BP following monotherapy with a CCB and an ACE inhibitor was not significantly different from the mean reduction in BP of combination therapy. The review generally showed that combination therapy is more effective than treatment with either monotherapy alone, based on mean decreases in either diastolic or systolic BP The studies provided no clear evidence that the effects of combination therapy were either additive or less than additive.