Abuse of prescription drugs is about to exceed the use of illicit street narcotics worldwide — and the shift has spawned a lethal new trade in counterfeit painkillers,  sedatives and other medicines potent enough to kill, a global watchdog warned Wednesday.

Already, prescription drug abuse has outstripped traditional illegal drugs such as heroin, cocaine and Ecstasy in parts of Europe, Africa and South Asia, the UN-affiliated International Narcotics Control Board said in its annual report for 2006.

In the United States alone, the abuse of painkillers, stimulants, tranquilizers and other prescription medications has gone beyond "practically all illicit drugs with the exception of cannabis," with users increasingly turning to them first, the Vienna-based group said.

And unregulated markets in many countries make it easy for traffickers to peddle a wide variety of counterfeit drugs through courier services, ordinary mail and the internet.

"Gains over the past years in international drug control may be seriously undermined by this ominous development if it remains unchecked," INCB president Philip Emafo said.

Discount medications that seem to be authentic often turn out to be cheap but powerful knockoffs concocted from recipes posted on the web, Emafo added.

"Instead of healing, they can take lives," he said, characterizing the danger as "real and sizable."

Up to 50 per cent of all drugs taken in developing countries are believed to be counterfeit, the board said, citing estimates from the World Health Organization.

Buprenorphine, an analgesic, is now the main injection drug in most of India, and it is also trafficked and abused in tablet form in France, where the INCB estimates 20 to 25 per cent of the drug sold commercially as Subutex is being diverted to the  black market.

Canadians ditching heroin for prescription narcotics

A study published in November 2006 in the Canadian  Medical Association Journal found that heroin was no longer the opiate of choice among many substance abusers in Canada — prescription narcotics such as morphine and OxyContin were taking its place.

Researchers studied street users in seven cities across the country in 2005, and found that heroin  remained the No. 1 illicit opiate only in Vancouver and Montreal. In the five other cities — Edmonton, Toronto, Quebec City, Fredericton and Saint John — more often than not, getting high meant taking prescription opioids like Percodan.

When the study was released, lead author Benedikt Fischer, an addiction researcher at the University of  Victoria, said the switch to highly addictive prescription narcotics among street users likely  represents just the tip of the iceberg

He said he suspected the numbers would be much higher if the general population was factored in.

The INCB said the number of Americans abusing prescription drugs nearly doubled from 7.8 million in 1992 to 15.1 million in 2003. Among their prescription drugs of choice: the painkillers oxycodone, sold under the trade name OxyContin, and  hydrocodone, sold as Vicodin and used by 7.4 per cent of college students in 2005.

Although the number of U.S. high school and college students abusing illicit drugs declined in 2006 for a fourth consecutive year, "the high and increasing level of abuse of prescription drugs by  both adolescents and adults is a serious cause for concern," it said.

Counterfeiters are exploiting intense demand for prescription drugs that can give a "high" comparable to cocaine, heroin or methamphetamine, the watchdog group said.