PEARLS No. 223, December 2009, written by Brian R McAvoy

Clinical question
How effective are alpha blockers in the treatment of primary hypertension?  

Bottom line
Based on the limited number of published randomised controlled trials, the blood pressure (BP) lowering effect of alpha blockers is modest (-8/-5 mmHg), compared to placebo. A dose response relationship for the BP lowering effect of alpha blockers could not be established. There were no clinically meaningful differences in BP lowering between 4 different alpha blockers (bunazosin, doxazosin, prazosin and terazosin). The review did not provide a good estimate of the incidence of harms associated with alpha blockers because of the short duration of the trials and the lack of reporting of adverse effects in many of the trials.  

Caveat
Given the high likelihood of publication bias, the estimates of BP lowering effect calculated are likely to be an overestimate of the real effect. The effect of alpha blockers on BP variability, pulse pressure, or heart rate could not be determined.  

Context
Alpha blockers are used as pharmacological agents for the treatment of hypertension. Despite nearly 30 years of research evidence and clinical use of alpha blockers, the dose-related BP lowering effect of this antihypertensive drug class is still not known.  

Cochrane Systematic Review
Heran BS et al. Blood pressure lowering efficacy of alpha blockers for primary hypertension. Cochrane Reviews 2009, Issue 4. Article No. CD004643. DOI: 10.1002/14651858.CD004643.pub2. This review contains 10 studies involving 1175 participants.