WASHINGTON (Reuters) - Expensive advertising of prescription drugs directly to consumers may do little to encourage sales, U.S. and Canadian researchers reported on Monday.

A pharmacist in a file photo. REUTERS/Mark Blinch

They said that even though companies spent an estimated $3 billion in 2005 on such ads in the United States, they did not appear to result in more prescriptions.

Most countries ban direct advertising of prescription medications, with the exceptions of the United States and New Zealand.

“People tend to think that if direct-to-consumer advertising wasn’t effective, pharma wouldn’t be doing it,” Harvard Medical School’s Stephen Soumerai said in a statement. “But as it turns out, decisions to market directly to consumers are based on scant data.”

The team at Harvard and the University of Alberta set up an experiment using French-speaking Quebec residents as their “control” group.

English-dominant Canadians see a great deal of U.S. advertising, but French-speaking Quebecois see far less and thus are less likely to be influenced, the researchers reported in the British Medical Journal.

The researchers looked at three drugs: Enbrel, or etancercept, sold by Wyeth and Amgen to treat rheumatoid arthritis and other conditions; Novartis AG’s now-withdrawn irritable bowel drug Zelnorm; and the Nasonex allergy treatment made by ScheringPlough Corp.

PHARMACY SALES

All three drugs were on the market for at least a year before the ads started and none were advertised via legal “soft” ads in Canada that allow mention of the drug’s name but not what it is for.

They looked at prescription data from 2,700 pharmacies compiled by IMS Health Canada and found no difference in sales for Enbrel or Nasonex after the U.S. ads began.

They did see a 40 percent increase in sales of Zelnorm in English-speaking Canada as soon as the U.S. ad campaign began -- a jump mirrored by U.S. sales. But after a few years sales flattened out, and the rise could have been because there were no alternatives for consumers, they said.

Pharmaceuticals are not typical consumer products, Soumerai said.

“A person needs to see an ad, get motivated by that ad, contact their doctor for an appointment, show up at the appointment, communicate both the condition and the drug to the doctor, convince the doctor that this drug is preferable to other alternatives, then actually go out and fill the prescription,” he said.

“This is a chain of events that can break at any point.”

The nonprofit Kaiser Family Foundation has come to similar conclusions in reports on direct-to-consumer ads.

In an April report the foundation found that 91 percent of adults surveyed had seen or heard advertisements for prescription drugs, but just one-third spoke to a doctor about a drug they saw advertised, and 54 percent of them got a prescription for a different drug.

Among doctors, 76 percent said they sometimes recommend a different prescription drug to a patient who mentions a drug ad and 5 percent said they frequently gave patients the drug.