Report cites new pills to treat impotence

Doctors say millions of men will benefit from a revolution in impotence treatment with the first oral medicines that promise to restore sexual functions. The closest of three pills in the pipeline, Viagra, could be sold as early as April, said experts.

Impotence is highly treatable, but there are drawbacks to current treatments: penile implants require surgery; vacuum-style devices that force blood into the penis interrupt lovemaking and injecting drugs into the penis or inserting a drug-carrying pellet into the urethra can be painful.

Three experimental pills promise to erase the discomfort, doctors at the National Institutes of Health said. Pfizer Inc.'s Viagra, or sildenafil, blocks an enzyme found mainly in the penis that breaks down a chemical produced during sexual stimulation. The longer that chemical, called cyclic GMP, stays around, the better chance of an erection. Unlike injection drugs, Viagra doesn't cause erections unless the man is sexually stimulated.

Tap Pharmaceuticals Inc.'s drug, apomorphine, affects chemicals in the brain region associated with initiating erections, according to Dr. Harin Padma-Nathan of The Male Clinic in Santa Monica, CA. Tap may seek FDA approval before 1999.

Zonagen Inc. is expected to seek FDA approval by year's end for Vasomax, an oral version of a current injection drug that dilates penile blood vessels.

Between 10 million and 20 million American men suffer impotence at some point in their lives. Impotence increases with age, and some 80 percent is caused by disease, particularly diabetes and heart conditions that restrict blood flow. Impotence also can be psychological or a side effect of certain drugs.