A Cochrane review included 92 studies with a total of 12 954 (baseline BP 157/101 mm Hg) evaluating the dose-related trough BP lowering efficacy of 14 different ACE inhibitors for primary hypertension. The best estimate of the blood pressure lowering efficacy of these 14 drugs ranged from –6/–4 to –9/–5 mm Hg. The data did not suggest that any one ACE inhibitor is better or worse at lowering blood pressure.
A dose of 1/8 or 1/4 of the manufacturer's maximum recommended daily dose (Max) achieved a BP lowering effect that was 60 to 70% of the BP lowering effect of Max. A dose of 1/2 Max achieved a BP lowering effect that was 90% of Max. A dose-response was present with a statistically significant difference between 1/4 Max and 1/2 Max. Further increases in the dosage beyond 1/2 Max did not result in a statistically significantly greater reduction in blood pressure. ACE inhibitor doses above Max did not significantly lower BP more than Max.
Combining the effects of 1/2 Max and higher doses gives an estimate of the average trough BP lowering efficacy for ACE inhibitors as a class of drugs of -8 mm Hg for systolic blood pressure (SBP) and -5 mm Hg for diastolic blood pressure (DBP). ACE inhibitors reduced BP measured 1 to 12 hours after the dose by about 11/6 mm Hg. Due to lack of reporting and the short duration of these trials this review did not provide a good estimate of the harms associated with this class of drugs.