"Herbal" Viagra and other so-called natural alternatives for treating impotence advertised on the Internet and in men's magazines are often contaminated with real drugs and could kill those who take them, researchers said.

They said the flood of e-mail spam touting alternatives to prescription erectile dysfunction drugs was a sign of how popular such products were, but the researchers suggested that governments monitor and regulate supplements more closely.

"These are being marketed as being safe and natural products," said Dr. Neil Fleshner of Princess Margaret Hospital in Toronto, Canada. "It is plausible that deaths have occurred or could occur."

Fleshner and colleagues bought seven "herbal" erectile dysfunction products to find out what was in them.

Two contained significant levels of prescription phosphodiesterase inhibitors -- sildenafil, sold by Pfizer under the brand name Viagra and tadalafil, Eli Lilly and Co's Cialis.

"We think the implications of this are quite dramatic," Fleshner told a news conference.

"Since these compounds are not natural, deliberate contamination of these products must be considered," added Fleshner, whose team presented the findings to a meeting of the American Urological Association in San Francisco.

The erectile dysfunction drugs affect blood flow and can be deadly when taken with certain heart drugs containing nitrates. The researchers said they would continue efforts to get the U.S. Food and Drug Administration to more closely regulate "alternative" products.

PRESSING FOR LEGAL CHANGES

Current law allows non-prescription supplements to be advertised so long as they do not make specific health claims, such as lowering cholesterol. However, the FDA does move to stop the marketing of products that contain prescription medicines.

"The law, in my opinion, is way off the mark," Dr. Ira Sharlip of Pacific Urology in San Francisco told the news conference.

A British study said other herbal products could also be dangerous.

Dr. Ramesh Thurairaja and colleagues at the Bristol Royal Infirmary in Britain did a "Google" Internet search using the words "herbal" and "Viagra."

"I actually picked up 160,000 hits last year," Thurairaja told a news conference. "Two weeks ago I typed the same two words in and got 690,000 hits."

Many of the sites also touted penis enlargement products, Thurairaja noted.

His team assessed the first 50 Web sites and found only 36 percent offered any advice on who should not use the products and just 21 percent listed potential side-effects.

Only 21 percent offered information from someone with medical training and 24 percent clearly stated that their information was not to replace doctors' advice.

"The commonest ingredients were yohimbe, ginseng and gingko biloba," Thurairaja said. "All these herbs have been previously investigated in the past and are known to have side effects such as skin reaction and cardiovascular disorders."

The AUA's Dr. Mark Moyad said many "alternative" products were being pushed by doctors.

"They sell products out of the office," Moyad said. "They haven't gone through any sort of clinical trial and (yet) they are 'doctor-approved'."

Reference Source 89