Canada's pharmacists are asking Ottawa to block the export of prescription drugs to the U.S., fearing that no action could result in a shortage of medicine for Canadians.

A coalition of four groups representing pharmacists and drug distributors has written to Health Minister Tony Clement after the U.S. Congress introduced a bill last week that would allow medicines meant for Canadians to be shipped south.

"Patients can't afford this risk," said coalition chair Louise Binder in a press release. "Canadians need reassurance today that prescription drugs will be there when we need them."

The coalition is calling on the Canadian government to immediately ban the export, both bulk and retail, of prescription drugs.

Domestic rules make prescription medications much cheaper in Canada than in the U.S. but the supply is restricted.

If the U.S. begins imported drugs from Canada, pharmacists fear that drug companies will end their pricing agreements.

The U.S. bill would allow pharmacies and wholesalers to import approved drugs from Canada, Europe, Australia, New Zealand and Japan. It would also allow individuals to buy personal drugs from Canadian pharmacies.

Clement does not think the changes will disturb the Canadian drug supply; however, he said he is monitoring the situation.

While it is possible that the new legislation may not be passed, the executive director of the Canadian Pharmacists Association told The Globe and Mail that his group believes Clement should act swiftly.

The bill, which has both Democrat and Republican support, is being touted as a free-trade measure between the two countries, said Jeff Poston.

"So it could be more awkward in the political sense, when the Canadian government chooses to take action, if it leaves it until we see the U.S. legislation passed," he said.

Poston said Clement should act before the government finds itself "in another politically embarrassing trade situation with the United States."

The coalition comprises the Canadian Pharmacists Association, the Ontario Pharmacists' Association, the Best Medicines Coalition and the Canadian Association for Pharmacy Distribution.