The biggest ad curbs on prescription drug advertising since the ads became a regular part of TV advertising in the 1990s are headed to an unexpectedly early Senate vote next week, prompting frantic lobbying by media, marketers and ad groups.

“It’s all hands on deck,” said Dick O’Brien, exec VP of the American Association of Advertising Agencies, as he rushed back to Washington from a conference in Toronto. The Senate is due to begin consideration of the legislation on Monday.

The groups are worried both about potential loss of billions in dollars in drug ads and the prospect congressional approval of drug ads curbs would lead to requests to curb ads for other products from high fat food to alcohol.

The Advertising Coalition, which includes ad groups, broadcasting groups, newspaper and magazine publishers and food marketers and CBS sent letters this week to every senator arguing the ad curbs violate the First Amendment and are bad for medicine.

“It is important to remember the number of Americans who would be harmed, by taking away information that could prompt a discussion with their doctor and the diagnosis of a serious medical condition.”

The group was also sending copies of opinions from First Amendment lawyers questioning the legislation’s constitutionality and getting broadcasters and publishers to call local legislators.

The ad curbs are part of Food and Drug Administration legislation sponsored by Sen. Ted Kennedy, D-Mass., and Sen. Michael B. Enzi, R-Wyoming, which just was sent to the Senate floor a week ago. At the time Sen. Kennedy suggested a floor vote was unlikely until late May or June.

The legislation which set fees for FDA drug review would allow the FDA to ban DTC for new drugs for up to two years. [A similar House calls for a three-year ban.]

Sen. Kennedy has suggested the FDA would impose the ban in very limited circumstances, but advertising, media and pharmaceutical groups are worried that the FDA would limit ad for most if not all new drugs. There is $4.5 billion spent annually on DTC.

Sens. Pat Roberts, R-Kan., Richard Burr, R-N.C., and Tom Coburn, R-Okla., have been urging replacing the ban with an increase in fines for “false” and “misleading” ads and the coalition endorsed that approach.