After discovering that a promising new drug caused multiple types of cancer in lab animals, the pharmaceutical company GlaxoSmithKline stopped developing the compound.
But the failed experimental drug, called GW501516, is making a comeback in another arena. Though it's not approved for human use — and likely never will be — it's among dozens of unregulated research chemicals being used by competitive bodybuilders, cyclists and other elite athletes seeking an edge.
These unapproved chemical compounds are sold by companies that purport to offer the substances for use in scientific experiments, which is legal. The buyer must agree the drugs will be given only to laboratory animals or used for in vitro research and will never be ingested by humans.
Yet so many athletes are trying GW501516 that the World Anti-Doping Agency, an independent international body, last month took the rare step of warning "cheats" about side effects, citing "serious toxicities." In the last two weeks alone, five cyclists — four from Costa Rica and one from Russia — were provisionally suspended when tests revealed they had the drug in their systems.
On bodybuilding websites, it's easy to find joking, thinly veiled comments referring to users as "lab rats."
"Should I wait until my rodents are between cycles to use these compounds?" one person asked on elitefitness.com, where visitors debate topics such as radical supplementation, performance-enhancing drugs and anabolic steroids.
"My rats feel great when they're on it," a forum user posted in March. "They can run on their little wheels for hours on end and not feel a thing. It also aids in the gym with muscular endurance. They also have told me they have a feeling of breathing easier when on GW. It's amazing stuff."
Some distributors of research chemicals openly advertise their products on bodybuilding sites and even sponsor chat boards and competitions.
"The 'research only' references are a 'wink-wink' kind of thing," said Lawrence Payne of the U.S. Drug Enforcement Administration. "We've seen about 200 new drugs flood the market over the last five years; most are unregulated, coming out of labs from China. It's the new frontier of drug enforcement."
And though the problem has been detected first among hard-core athletes, some experts say whatever top competitors do to get ahead inevitably is copied by others, including youngsters and recreational athletes, as well as people looking to improve their physique.
"As a research scientist, you feel both shock and anger when you're developing a medicine to help someone live longer or walk down the street without pain, and you find out people are abusing it and using it to cheat in sport," said Mark Luttmann, of GlaxoSmithKline, who works with the anti-doping agency to share confidential information on emerging compounds. "That's what really gets to you."
Luttmann said he is particularly concerned about young athletes emulating those who take illegal performance-enhancing drugs.
"Elite athletes know what they are doing is wrong," he said. "What we need to do is reach the kids. That's a huge role we play."
GlaxoSmithKline doesn't manufacture GW501516 or authorize its sale. According to the DEA, such products are often produced overseas, mainly in Chinese labs, which often can find in scientific journals the information necessary to manufacture them.
Many journals "insist we publish the structure" of an experimental drug, said Pauline Williams, who leads GlaxoSmithKline's anti-doping initiative.
The legality of unregulated chemicals depends on the circumstances, said Rick Collins, a New York criminal defense attorney whose practice centers on performance-enhancing drugs and dietary supplements.
A chemical sold to scientists for the purpose of animal research requires no federal approval. But if that same chemical is sold to consumers for use in the body, it is considered an "unapproved, misbranded or adulterated" drug because of the dangers it may pose to health, according to the Food and Drug Administration.
"The question isn't whether a drug is legal or illegal; it's whether the compound is regulated," said the DEA's Payne. "The danger is that people are putting something into their body that the government hasn't gotten its hands around."
As for the person taking the substance, "typically, American laws don't make the personal use of an unapproved drug illegal," Collins said.
Those who distribute these types of chemicals to be used as drugs, however, can face charges of mail fraud or misbranding of drugs.