Alpha-blockers associated with increased risk of stroke in older men

Older men starting α-blockers-blockers, commonly used for treating enlarged prostates, have a higher risk of ischemic stroke during the initiation phase, although this effect is not apparent in men already taking other blood pressure medications, found new research in CMAJ (Canadian Medical Association Journal).

Alpha-blockers were developed to control hypertension but are now used mainly in older men with prostate hypertrophy because they seem to be inferior to other first-line blood pressure drugs in providing cardiovascular protection. They are strong vasodilators and can have adverse effects. Men starting α-blockers can experience a large drop in blood pressure with the first pill or in the following days, which increases the risk of stroke.

A study of older Taiwanese men (over age 50) looked at the risk of stroke during the initiation phase of α-blockers. The study involved 7502 patients with a mean age of 71 years when they began treatment with α-blockers. Each patient had both a first stroke and a new prescription of α-blockers within the 3-year study period.

"We observed an increased risk of ischemic stroke in the early initiation period (within 21 d after the start of treatment) and a reduced risk in the late initiation period (22-60 d after the start of treatment)," writes Dr. Chao-Lun Lai, Department of Internal Medicine and Center for Critical Care Medicine, National Taiwan University Hospital Hsin-Chu Branch, Hsin-Chu, Taiwan, with coauthors.

Men who were not taking other blood pressure drugs had a two-fold increased risk of ischemic stroke during the early initiation period than men in whom α-blockers were initiated later. However, the authors also found that men already taking other blood pressure medications had no increased risk of stroke, perhaps because they were used to the medications and their effect in stabilizing blood pressure.

"We recommend caution when prescribing α-blockers to patients who are not taking other antihypertensive medications," they conclude.

The authors note that, because the study was conducted among mainly ethnic Chinese men in Taiwan, further study is needed to determine whether other ethnicities are also at increased risk of stroke.