A derivative of the opium poppy, OxyContin is a painkiller that is sometimes crushed and snorted by addicts. (Canadian Press)

Pharmacies are on high alert after a string of OxyContin robberies in Winnipeg and rural Manitoba.

Two pharmacies were robbed in Winnipeg's North Kildonan neighbourhood last week and there were attempted robberies at four others across the city.

There were also attempted robberies at drugstores in the communities of Stonewall and Teulon, according to the Manitoba Pharmaceutical Association.

Ronald Guse, MPA registrar, said pharmacists need to assess their risk and be prepared.

For the second time this year, the Manitoba Pharmaceutical Association has issued an alert to its nearly 1,300 members in the province.

"There's no way of preventing this, you know all you can do is put up barriers and and try to make your pharmacy the least likely … to be subject to an armed robbery but there's no absolute thing that would prevent that from happening," he said.

The first alert was sent out in response to a rash of robberies in Winnipeg in May.

A spokesperson for Canada Safeway in Winnipeg said several of it's pharmacies have stopped carrying OxyContin because of the robberies.

Some pharmacies recently decided not to carry OxyContin, including some Winnipeg Safeway locations.

Most pharmacies in the city have also reduced the amount of OxyContin in their stores and posted notices that large quantities of the drug are not available.

A derivative of the opium poppy, OxyContin is sometimes crushed and snorted by addicts.

It is highly addictive and known on the street as hillbilly heroin.

The illegal sale of the drug has been increasing on the streets of Winnipeg in recent years.