Erection Drugs May Pose Risks With Other Treatments (Update2)

Jan. 5 (Bloomberg) -- Erectile dysfunction pills made by Pfizer Inc., Eli Lilly & Co. and Bayer AG may lead to dangerous side effects if combined with one of 56 common medicines, consumer advocates said.

The Washington-based group Public Citizen posted a list online today of prescription drugs and herbal remedies to avoid when taking Pfizer’s Viagra, Lilly’s Cialis or Bayer’s Levitra. The 56 products range from treatments for high blood pressure and chest pain to grapefruit juice and St. John’s wort.

An estimated 15 million to 30 million men have difficulty getting or keeping an erection, according to the U.S. National Institute of Diabetes and Digestive and Kidney Diseases. Viagra’s U.S. approval in 1998 offered a convenient alternative to older injections for erectile dysfunction, and widespread marketing of all of the pills has eased much of the taboo about treating the disorder.

“Those who take erectile dysfunction drugs are generally older men, who are more likely to be taking other medications as well,” said Sidney Wolfe, director of Public Citizen’s health- research group, in an e-mailed statement. “It is critical that they be aware of the potential for dangerous interactions.”

Some of the drug-interaction risks are already noted in the pills’ prescribing information.

‘Proven Safety’

“Viagra has a proven safety profile that has been well established in extensive post-marketing studies and in more than 120 clinical trials,” said Pfizer spokeswoman Sally Beatty in a telephone interview. “Viagra’s product label accurately and responsibly reflects the safety profile of this important medicine.”

Spokesmen for Indianapolis-based Lilly and Leverkusen, Germany-based Bayer weren’t immediately able to comment.

Comprehensive information about Levitra’s potential interactions with other medications is available in the full product insert and the patient information leaflet, though patients also are encouraged to discuss these issues with their doctors, said Julie Lux, a spokeswoman for Schering-Plough Corp., of Kenilworth, New Jersey, which helps market Levitra in the U.S. with GlaxoSmithKline Plc, of London.

Viagra, Cialis and Levitra work by relaxing muscles in blood vessels, which increases blood flow to the penis and spurs an erection. This may be amplified when taken with certain medicines for hypertension, causing a dangerous drop in blood pressure that may lead to a heart attack or stroke, Public Citizen said.

Other drugs prevent the body from appropriately breaking down erectile dysfunction pills, leading to either a toxic buildup of medicine or a less effective treatment, Public Citizen said.

To contact the reporter on this story: Catherine Larkin in New York at clarkin4@bloomberg.net.

To contact the editor responsible for this story: Reg Gale at rgale5@bloomberg.net.