WASHINGTON – Anthony Iwaszko used to fill his prescriptions through mail-order pharmacies in Canada, where he found the prices for his costly hypertension and cholesterol medicines were substantially lower.

Now, the 73-year-old retiree from Belma, N.J., purchases all of his medicines in the United States.

“I stopped buying from Canada about two years ago when I was able to get the new Medicare Part D prescription drug coverage,” Iwaszko said.

Only a few years ago, there was a mass movement by elderly Americans to “reimport” drugs from Canada, where many brand-name medicines cost half of what they sold for at pharmacies in the United States. Canadian pharmacies were frequent advertisers in newspapers and on Web sites.

Today, more and more seniors like Iwaszko have given up buying their medicine from Canada. By some estimates, the flow of prescription drugs across the border has been cut in half over the past few years.

“The business certainly has decreased,” said Gord Haugh, head of the Canadian International Pharmacists Association. “At the height of business about three or four years ago, we were probably approaching about a billion dollars in sales, and I think it is probably down now to between $400 million and $500 million.”

Haugh and other industry experts said the sharp decline in reimportation – the practice of buying American-made drugs from foreign sources – is due to a confluence of events. Those include the Medicare prescription drug benefit that took effect two years ago, the declining value of the U.S. dollar versus the Canadian “loonie,” and the growing availability of lower-cost generic medicines through discount programs at stores like Wal-Mart and Target.

Haugh’s association represents legitimate pharmacies that are licensed by the Canadian provincial authorities and require verifiable prescriptions from physicians before selling to Americans. A few years ago, he said, there were as many as 50 pharmacies in the association; now, because of consolidation and the decline in business, there are “about 20 members, and five viable companies that are not members.”

Big American pharmaceutical companies have cut back on supplies to Canadian pharmacies that sell to Americans, he said, so his members have been forced to contract with counterparts in Europe and elsewhere. These days, when Americans order drugs from a legitimate Canadian pharmacy, some of the medicines may end up being shipped from other countries, he said.

U.S. law prohibits Americans from buying American-made drugs abroad and reimporting them. But the law has never been widely enforced, with tens of thousands of people annually choosing to make purchases from Canada and other countries where prices of brand-name drugs are regulated and generally much cheaper.

Consumer advocates have long favored reimportation to help those in need and to place pressure on the pharmaceutical industry to lower prices.

The drugmakers have adamantly opposed reimportation, seeing it as a back-door way to undercut their pricing and profits. They argue it will mean less money to invest in research and development of new medicines, and warn that the safety of reimported drugs cannot be guaranteed.

Billy Tauzin, head of the Pharmaceutical Researchers and Manufacturers of America, the leading industry trade group, said the Medicare drug benefit has provided good coverage for seniors and allows them to buy drugs “in a regime they know is safe.”

“That’s an important consideration,” Tauzin said. “Canada is a big trans-shipment center for drugs coming from all over the world. Most Americans have a high confidence level that the medicines they buy in America are safe, and that is not true in other parts of the world where counterfeits are prevalent.”

Congress has debated the reimportation issue off and on for more than a decade.

It has passed legislation making it permissible for individuals to reimport medications, but only if the American government certifies they can guarantee the safety of the medicines. Health officials in both the Clinton and Bush administrations, however, have refused to provide that certification.

All three presidential candidates – Sens. John McCain, R-Ariz.; Barack Obama, D-Ill.; and Hillary Clinton, D-N.Y. – have signaled support for a reimportation plan to help reduce prices, giving backers hope.

A beleaguered Food and Drug Administration recently acknowledged to Congress it does not have the resources or manpower to regularly inspect thousands of foreign plants that supply an ever-increasing number of drugs to the U.S market through normal channels, let alone add new responsibilities to monitor reimportation.