Benign prostatic hyperplasia is a common condition. An estimated 50% of men over the age of 50 years have BPH. Presenting symptoms include urinary hesitancy, urgency, decreased strength of stream, and double-voiding. In my practice, nocturia is usually what starts the conversation.
First-line therapies include alpha-1 adrenergic receptor antagonists ("alpha-blockers") and 5-alpha-reductase inhibitors ("5-ARIs"). Alpha-blockers are effective, but are associated with orthostasis and syncopal events. Orthostasis has been more commonly associated with medications such as doxazosin and terazosin (in other words, "first-dose phenomenon"). Tamsulosin, a uroselective agent, is supposedly less likely to cause decreases in blood pressure.
But is tamsulosin associated with clinically important dips in blood pressure?
Steven T. Bird, Pharm.D., of the Food and Drug Administration’s Center for Drug Evaluation and Research, and his colleagues published the results from a retrospective, population-based cohort study examining whether tamsulosin is associated with hypotension and hospitalization (i.e., "severe hypotension"). Using information from a database of paid claims from more than 102 health care plans, the authors identified men aged 40-85 years who received alpha-blockers and 5-ARIs. In total, 297,596 new users of tamsulosin and 85,971 new users of 5-ARIs were identified. Median duration of use was 14 weeks for tamsulosin and 34 weeks for 5-ARIs (BMJ 2013;347:f6320).
Patients who took tamsulosin were 2.12 times more likely to experience severe hypotension during the first 4 weeks of therapy (95% confidence interval: 1.29-3.04). During weeks 5-8, severe hypotension was 1.51 times more likely in those who used tamsulosin (95% CI: 1.04-2.18). No significantly increased risk of hypotension was noted during weeks 9-12. Drug restarting (after a 4-week gap) was associated with a significantly increased risk of severe hypotension through 8 weeks of therapy, but not during weeks 9-12. Patients also were at an increased risk of hypotension during maintenance therapy.
In clinical trials of tamsulosin, patients were retained at research sites for 8 hours after the first dose and counseled on the effects of orthostatic hypotension – an environment that "may not apply to treatment practice in the real world," the authors cautioned. The incidence of hypotension in those studies was 12%, compared with 6% for placebo.
We should remind our patients that tamsulosin can cause clinically important dips in blood pressure. Simple instructions about sitting on the edge of the bed when going from supine to standing could make the difference between a better night’s sleep and a worse one in the hospital.
Dr. Ebbert is professor of medicine, a general internist at the Mayo Clinic in Rochester, Minn., and a diplomate of the American Board of Addiction Medicine. The opinions expressed are those of the author. He reports no conflicts of interest.