VANCOUVER, B.C. - At the Salt Lake City Olympics, blood doping athletes used a brand new drug called Aranesp. Six years later at the Beijing Games, the dopers turned to Mircera, a newer drug that had just hit the market.

As the Vancouver Olympics are about to kick off, anti-doping experts are wondering if the newest kid on the blood doping block, Hematide, will be making an unwelcome appearance at the Games.

If Hematide is detected in the coming weeks, it will point to an alarming problem that extends beyond doping in sport. Unlike the earlier drugs, Hematide hasn't yet been licensed by drug regulators and should not be available.

The drug is in the final stages of clinical trials, where tight control is supposed to be exercised over limited quantities of what is still an experimental drug used to treat people with severe anemia. But that's no guarantee the drug isn't already in the hands of cheats, some in the anti-doping effort say.

"I would say it's the agent of choice today if they can figure out how to get it. And they can usually do that. These folks always get the drugs before other people do," says Dr. Don Catlin, a U.S. expert who is the dean of the anti-doping community.

"All of us who are in this business are trying to get a method for Hematide (detection)."

Several endurance sports have been plagued by blood doping, the name used for a series of techniques by which athletes boost their red blood cell counts. The goal is to be able to pump more oxygen to muscles starved for it by the end of a taxing event.

Blood doping infractions have been logged in sports like cycling, cross-country skiing, biathlon and long-track speedskating.

Sometimes athletes cheat by drawing out some of their own blood during periods when they are not competing and transfusing it back shortly before an event. And sometimes athletes use drugs developed to treat anemia, where the body's ability to produce red blood cells is hindered by a medical condition such as kidney failure.

Hematide is one of these drugs. And Harm Kuipers, a doping expert who is on the medical commission for the International Skating Federation, agrees some elite athletes may already be using it to give themselves an edge over their rivals.

"I have no proof. But I think it's quite possible that it's used, yes," says Kuipers, a former Olympic speedskater and now a sports medicine specialist at Maastricht University in the Netherlands.

"Even products that are not brought to market yet, they are already used."

The company developing Hematide knows it is viewed as a potential doping agent. Affymax, of Palo Alto, Cal., is working with the World Anti-Doping Agency (WADA) to speed development of a test for the product, one of a class of drugs called erythropoeisis-stimulating agents or ESAs. (Erythropoeisis is the process of red blood cell generation.)

Sylvia Wheeler, executive director of corporate communications for Affymax, says the company has given WADA the drug so agency-approved laboratories can start looking for ways to detect it.

Wheeler says the drug should not be in the hands of athletes.

"Because it is an experimental drug we do have a lot of measures in place to track inventory and know where the product is.... (But) if there is a will, there could be a way to circumvent that," she admits.

Catlin says knowing what's in the pharmaceutical pipeline and how upcoming products might help athletes gain a physiological advantage is a key part of doing battle against the dopers.

To that end WADA works with what the anti-doping folks call "ethical pharma" to try to close the gap between the point when a doping drug first starts to be used and when a test to detect it can be developed and validated.

"It's one thing to know about it. It's another thing to have a test and to have it validated and whatever. That's the hard part, the latter," says Catlin, who oversaw the anti-doping operations at the Los Angeles, Atlanta and Salt Lake City Olympics and who now runs the non-profit agency Anti-Doping Research Ltd.

Though they have a bad name in the context of sports, ESAs have a legitimate and critical medical purpose. They are used to treat severe anemia triggered by kidney failure, some forms of cancer or the chemotherapy used to treat some cancers.

But cheats in endurance sports long ago twigged to the doping potential of these drugs.

Erythropoeitin or EPO was probably in use for years before French scientists finally managed to devise a test for it in 2000. At the Salt Lake City Games, Catlin's lab revealed they could detect Aranesp, a new long-acting ESA that hadn't even been on the market for a year at that point.

By the time Beijing hosted the 2008 Games, the dopers had moved on to Mircera, known as CERA. It too is a long-acting formulation, designed so that people who legitimately need the drugs don't have to go for infusions several times a week.

At Beijing there was no test for CERA, but the drug was clearly in use. Last year, after a test was devised, the IOC ordered the retesting of stored samples from those Games. They found five positives, including one from a gold medallist who was stripped of his title.

The experts think it's inevitable that Hematide is next up, though not all share Catlin's belief the drug may already be in play.

"We have no evidence so far that athletes could get hold of these drugs before they are brought to the market," says Christiane Ayotte, director of the anti-doping lab for the Vancouver Games.

But once the drug hits the market, "be sure that the athletes will be there the first day," she says.

If it is already being used, will Hematide be detected during the Vancouver Games? Catlin says the drug has a different chemistry and cannot be detected by the test for EPO - "you have to have a new and better test."

Ayotte won't say if one has yet been developed.

"Well, it remains to be seen if we would be ready or not. I would not divulge our secrets yet," she says.

But even if the test isn't ready now, that doesn't mean people who use the drug at Vancouver can assume they'll get off scot-free, Catlin says.

The IOC is has ordered that samples be stored for eight years and has told athletes it will order retroactive testing if a new detection assay is developed in that time frame.