Men who have recently begun alpha-blocker therapy, often prescribed for prostate hypertrophy, may have an increased risk of ischemic stroke, according to a report published online ahead of print December 7 in the Canadian Medical Association Journal. The risk was more pronounced among patients who were not taking other antihypertensive agents.


“We recommend caution when prescribing alpha-blockers to patients who are not taking other antihypertensive medications,” wrote lead author Chao-Lun Lai, MD, PhD, and colleagues. 


The study included 7,502 men in Taiwan who were aged 50 years or older; mean age was 71 years at initiation of alpha-blocker treatment. 


The investigators found an increased risk of ischemic stroke among all patients within 21 days following initiation of alpha-blocker therapy and a reduced risk 22 to 60 days after beginning treatment, compared with the risk before exposure to the medication. Among patients who were not taking other antihypertensive agents, there was a twofold increased risk of ischemic stroke during the early initiation period than during the later period. In contrast, men who were already taking other antihypertensives had no increased risk of stroke. 


“One possible explanation of our findings was that patients without underlying hypertension were vulnerable to the first-dose effect of alpha-blockers and contributed to the observed increase in risk of ischemic stroke in the early initiation period of alpha-blockers in the whole study population,” the authors wrote.


“In contrast, patients with underlying hypertension appeared to be tolerant of the first-dose effect of alpha-blockers, benefited from the positive influence of alpha-blockers on cerebral blood flow, and contributed to the observed decrease in risk of ischemic stroke in the late initiation period in the whole study population,” the investigators reported.