August 19 (HealthDay News) -- A daily dose of the erectile dysfunction drug tadalafil (Cialis) helped relieve lower urinary tract symptoms in men with signs of enlarged prostates, according to a new study.

More than 50 percent of men age 50 and older have lower urinary tract symptoms, including increased urination frequency and urgency, straining, intermittence, incomplete emptying or a weak urinary stream. Current drugs used to treat the condition can produce side effects such as dizziness, low blood pressure and sexual dysfunction.

In this study that included 1,056 men in 10 countries, the men were randomly divided into five groups that received either a placebo or tadalafil doses of 2.5, 5.0, 10.0 or 20.0 milligrams a day. All doses of the drug were superior to a placebo for relieving lower urinary tract symptoms (LUTS), with statistically significant effects at four, eight and 12 weeks.

The study, which included researchers from drug maker Lilly, is published in the October issue of The Journal of Urology.

"Since reports of erectile dysfunction (ED) incidence, pathophysiology and treatment have shown a possible link between [enlarged prostate] and ED. PDE5 inhibitors like tadalafil (Cialis) have received increased attention for treating BPH LUTS, although they are currently only approved for ED. The half-life of tadalafil is 17.5 hours, making it suitable as once daily therapy. Although the precise mechanism of action by which PDE5 inhibitors may alleviate LUTS is not completely understood, several putative mechanisms are currently under investigation." researcher Dr. Claus G. Roehrborn, professor of urology at the University of Texas Southwestern Medical Center at Dallas, said in a journal news release.

SOURCE: Elsevier Health Sciences, news release, Aug. 19, 2008