Studies on the topic were presented this week at the annual meeting of the American Urological Association in Anaheim, Calif.
"Before, we looked at these two conditions as two different diseases," says Kevin McVary, MD, professor of urology at Northwestern University Feinberg School of Medicine in Chicago, who moderated a press briefing.
But in the past three or four years, he says, the thinking among urologists has changed.
Sexual performance in men seems to decline as their prostate enlargement becomes more severe, experts have begun to notice. Doctors also notice that men with milder prostate problems often have less erectile dysfunction (ED) than do those with moderate or severely enlarged prostates and urinary symptoms.
"These two diseases -- erectile dysfunction and the lower urinary tract symptoms associated with benign prostatic hyperplasia -- are probably linked," McVary says.
Conditions Increase With Age
Prostate problems and ED problems both tend to increase with age. About 31% of men aged 50 to 59 have an enlarged prostate (also known as benign prostatic hyperplasia or BPH); 44% of those 70 and older have an enlarged prostate, according to the National Institutes of Health. As the gland enlarges, it constricts the urine-carrying tube called the urethra, making it difficult to empty the bladder.
Medications are prescribed to relieve the symptoms. Some medications work by relaxing the muscles at the neck of the bladder and prostate; others inhibit a hormone that contributes to the growth of the gland.
Erectile dysfunction, defined as an inability to get or keep an erection, is experienced by 20% to 46% of men aged 40 to 69, according to the NIH. Medications to treat erection problems help increase blood flow to the penis when a man is sexually stimulated.
A once-a-day dose of Cialis helped men with erectile dysfunction and moderate to severe urinary tract symptoms due to an enlarged prostate improve sexual functioning, says Marc Gittelman, MD, a urologist in Aventura, Fla., and a study researcher.
Of the 281 men who enrolled in the study, "81% were sexually active, and they were in their low 60s," he says. All had moderate to severely enlarged prostates and urinary problems; 68% of the sexually active men had a medical history of erectile dysfunction. Gittelman's team assigned about half to take placebo and half to take Cialis.
At the end of 12 weeks, men who took Cialis -- first 5 milligrams a day and then up to 20 milligrams -- had significantly higher scores on a standard index of erectile function, he says.
He especially wanted to see if they were as likely to do well if their urinary problems were severe as opposed to moderate. "They are equally statistically likely to respond to a dose of Cialis," he says.
The study was funded by Lilly, which is the maker of Cialis.
In another study, 223 men aged 45 to 64 who had urinary symptoms due to an enlarged prostate were assigned either to a group given 10 milligrams of Levitra twice daily for eight weeks or a placebo for the same time period.
Compared with placebo, treatment with the ED drug significantly improved the men's quality-of- life scores and their reports of urinary obstruction and irritation, says Boris Schlenker, MD, a urologist at Ludwig-Maxmillians-Universitaet Hospital in Munich, Germany, who presented the data. Erectile function improved in those who took the ED drug.
"Levitra is a promising new drug for men with lower urinary tract symptoms, but we need long-term data on how it might affect the progression of the disease," he says.
The Viagra Study
In a third study, McVary assigned 369 men aged 45 and up who had both erectile dysfunction and lower urinary tract symptoms to take either 50 milligrams of Viagra every night, 50 milligrams of Viagra an hour before planned sexual activity, or to take a placebo. The dose increased to 100 milligrams after two weeks.
When he evaluated their erectile function and urinary symptoms, he found 73% of the men with severe symptoms improved to having mild or moderate symptoms at the end of the study.
"The changes in prostate symptom scores were dramatic," he says. "They compete with alpha blockers." Alpha blockers are one type of drug commonly prescribed to treat urinary symptoms associated with an enlarged prostate. The more severe the urinary symptoms, the greater the relief, he says.
The study was funded by Pfizer, which is the maker of Viagra.
"This really is cutting-edge," says Gittelman.
The experts aren't sure if the ED drugs will eventually supplement or replace drugs used for urinary problems associated with an enlarged prostate, or if new formulations might be developed to deal with both conditions.
Some men on the ED drugs did report side effects, says Schlenker, with the most common in his study being headache.
It's not known exactly why the ED drugs also help the urinary symptoms, McVary says. By increasing blood flow to the pelvic area, the ED drugs may help relax the bladder enough to relieve the urinary problems.