Spending on direct-to-consumer drug advertising in the United States rose by a staggering 330 per cent in the first decade after drug companies were freed to pitch their wares directly to the public, rising to just under $30 billion US for the year 2005, a new study shows.

The work, published Thursday's issue in the New England Journal of Medicine, revealed that new ad campaigns typically start within a year of a drug's arrival on the market — a time when it has been suggested that drug companies should not be allowed to advertise a drug.

Earlier this year, a report published by the U.S. Institute of Medicine recommended that the American drug regulator, the Food and Drug Administration, bar drug companies from advertising prescription drugs in the first two years after they come to market. It is during that period when a drug first starts to be broadly used that side-effects not seen in clinical trials can become evident.

"Our data show that a mandatory waiting period on advertising for new drugs would represent a dramatic departure from current industry practices," wrote the authors, from the University of Pittsburgh, Harvard School of Public Health and Vanderbilt School of Medicine in Nashville, Tenn.

Calls to restrict advertising on prescription drugs in the U.S. have gained momentum in the fallout over Vioxx, the former blockbuster painkiller that was withdrawn from the market after studies revealed it increased the risk of heart attack and stroke in users. The drug and others in its class were heavily advertised.

But lead author Julie Donahue said any move to institute a mandatory moratorium on prescription drug advertising in the first year or two after drugs hit the market would be unlikely to withstand the scrutiny of U.S. courts.

"My understanding — and I'm not a legal scholar — is that American courts have been very protective of commercial [freedom of] speech … So unless the courts were convinced the harms outweigh the benefits, I don't think they would support a ban," said Donahue, who teaches in the University of Pittsburgh's graduate school of public health.

Canadian court challenge on drug ad ban

Whether Canadian courts will take a similarly supportive position on direct-to-consumer drug ads remains to be seen.

CanWest Global Communications — owner of a number of major Canadian newspapers and the Global TV network — has launched a challenge of Canada's ban on prescription drug advertising that is currently before Ontario Superior Court.

Donahue is an expert witness for CanWest in its legal battle and has taken consulting fees from drug giant GlaxoSmithKline.

Only the United States and New Zealand allow drug makers to advertise directly to consumers.

In Canada, pharmaceutical companies are permitted to either advertise the name of a drug, without making any claims about its use, or advertise a medical condition and remind readers, listeners or viewers that if they have this condition they can seek help from their doctors.

Proponents of direct-to-consumer drug ads — and Donahue is one — argue the ads inform the public and spur people to seek treatment for under-treated or poorly controlled conditions such as diabetes or high blood pressure.

Others say the Donahue review underscores the arguments for not allowing pharmaceutical manufacturers to advertise to the public.

"What they're presenting feeds into concerns about the advertising rather than being something that would dismiss those concerns," said Barbara Mintzes, who teaches at the Centre for Health Services and Policy Research at the University of British Columbia.

Mintzes and other opponents argue that the advertisements drive people to seek drugs they may not need, or to seek more expensive new drugs when cheap generic medications could be equally effective.