Botox is perhaps best known for reducing facial wrinkles, but University of Pittsburgh physicians say it can also reduce the size of a man's enlarged prostate gland.

One injection of the botulinum toxin can shrink the prostate for six to nine months, providing relief from symptoms that increase the frequency and the difficulty of urination in men.

"It's definitely not ready for prime time," emphasized Dr. Michael Chancellor, a Pitt urologist who yesterday presented findings from animal studies and from a small clinical trial in Taiwan at the International Continence Society meeting in Montreal. "But it's intriguing," he added, noting he offers this "off-label" use of Botox for UPMC patients who aren't adequately helped by conventional treatments.

Larger studies to demonstrate the treatment's safety and effectiveness will be necessary before it is likely to spread beyond the relative handful of urologists who now offer the treatment, said Chancellor, who is seeking a federal grant for such a study.

Allergan Inc., the maker of Botox, says it plans to launch its own U.S. clinical trial by the end of the year.

An estimated 6 million men have enlarged prostates, a condition that becomes more common as men grow older. About a third of all men over age 75 have some degree of prostate enlargement. It is distinct from prostate cancer, another common disease in men. Benign prostatic hyperplasia occurs as the prostate gland grows bigger with age and starts to impinge on the urethra, which carries urine from the bladder.

Men with enlarged prostates may feel the need to urinate more frequently and may have more difficulty starting and stopping the urine flow.

Botulinum toxin type A has found a number of uses as a muscle relaxant since it was first approved by the FDA in 1989 for treating eye muscle disorders.

But the mechanism by which Botox works in prostatic disease is a bit different, Chancellor said. As reported yesterday, injections into the prostates of laboratory rats showed that the toxin induced apoptosis, or programmed cell death, in some of the prostate cells, helping to reduce the size of the gland.

The injections also made the glands less sensitive to the hormone epinephrine and similar substances, which cause the prostate and bladder muscles to tighten up. The walnut-size gland surrounds the urethra, so when the gland contracts it can be difficult to void urine. Botox allows the gland to relax, improving flow.

"The drug can treat prostate problems when the pills don't work because we can alter how body chemicals talk to the prostate," Chancellor said.

Surgery can be effective in treating severe symptoms, though the operation includes a small risk of bleeding, infection and impotence. Drugs such as Proscar and Avodart can block hormones that cause the gland to enlarge, but they don't work for all men. A family of high blood pressure medications, known as alpha blockers, also can reduce symptoms, but again are not always effective.

Chancellor and his Taiwan colleagues are presenting findings from 16 patients treated in the Taiwanese clinical trial. He said he also has treated UPMC patients who do not want surgery and have not been helped by the conventional drugs. But the number of patients treated remains small, around 50.

The technique itself is simple, he noted, and is much the same as would be used to do a biopsy of the prostate.