OxyContin tablets may be crushed and snorted by abusers. (CBC)

Ontario will lead a national probe into potential abuse of the drug OxyContin, a prescription painkiller that is sometimes crushed and snorted by addicts.

The value of prescriptions for the pharmaceutical paid for by Ontario's public drug plan has tripled in the last five years, making it one of the most popular medications.

Last year, the total tab for OxyContin was $54 million under a provincial program that provides free medications to seniors, people on social assistance and people with disabilities.

The province's Health Ministry wants to find out whether the people getting OxyContin, a slow-release form of the opioid oxycodone, really need it. Health officials from the provinces and territories agreed last week that the ministry will lead an investigation.

The slow-release drug is intended for people in extreme pain, but addicts may crush the tablets and snort them, or inject a liquid solution of the drug into their veins for an instant high like the one heroin gives.

The drug has a history of abuse. A $4 pill can sell for up to $45 through the underground market.

Critics say OxyContin is given out too freely, a phenomenon related to double doctoring — people who visit multiple doctors complaining of pain symptoms to obtain the drug for resale purposes.

In Ontario, there is no way to track who has been prescribed the painkiller, also known as "hillbilly heroin." It's estimated that in the last five years, more than 450 people have died in Ontario from overdoses involving oxycodone.

Stronger safeguards planned in U.S.

Also on Monday, federal health regulators in the United States said makers of opioid painkillers will have to strengthen safety measures to prevent misuse and abuse of the medications, including OxyContin.

Opioids are a class of powerful, highly addictive narcotics often prescribed to relieve chronic pain. Other examples include morphine and methadone.

The U.S. Food and Drug Administration said it was concerned about rising numbers of overdoses and accidental deaths over the last 10 years related to the drugs, which are sold as pills and patches.

"We're focusing on these products because they generally contain very high doses of the drugs and need to be used very carefully," said Dr. John Jenkins, the FDA's chief of new drugs.

The drugs are typically used by people already taking narcotics, such as cancer patients, to treat severe flare-ups of pain.

The FDA said it will meet with 16 drugmakers on March 3 to discuss stronger warning labels, restrictions on who may receive the drugs and cautionary letters for physicians.

The announcement applies to drugs already on the market.

With files from Associated Press