GHB, or gamma-hydroxybutyrate, has gained notoriety as a date-rape drug because it can cause drowsiness and loss of inhibition -- hence its nicknames Easy Lay and Grievous Bodily Harm.

Colourless and odourless, the drug is often used to spike the drinks of women, knocking them out or making them unable to stop a sexual advance.

Once ingested, it takes effect within 10 to 20 minutes and lasts up to four hours.

"A victim loses any sense of will. She's unable to decide for herself," said Nathalie Brault, a psychologist at the sexual-assault clinic at Montreal's Hôtel-Dieu hospital.

Police began to take notice of the drug in the 1990s, as women reported waking up bruised and naked, unable to recall what had happened to them.

The drug causes those who have ingested it to suffer a complete blackout, making it difficult to press charges against an aggressor.

"The person can absolutely not know what happened to them," Ms. Brault said.

Victims may be spared of fear while they're being raped, but they are often traumatized by the time the drug wears off. Ms. Brault estimates that 15 per cent of the 230 cases she treats annually are victims of date-rape drugs.

Some experts consider GHB more dangerous than other so-called date-rape drugs because it can be easily manufactured in home labs from readily available ingredients. The ingredients are frequently sold over the Internet to teens and young adults.

GHB is a mixture of common industrial chemicals. The drug and its derivatives, GBL and 1,4 BD, act as depressants on the central nervous system.

The drug can be extremely dangerous, causing seizures, severe respiratory depression, and fatal comas. The U.S. Drug Enforcement Administration has documented 72 deaths relating to GHB and its derivatives.