The Food and Drug Administration, in a move that could cost the nation's pharmaceutical industry millions of dollars in sales, said yesterday it will propose regulations to ban Medicare and Medicaid payments for dozens of popular prescription drugs that are not considered effective.

The Public Citizens Health Research Group, which had petitioned the government to ban the payments, immediately attacked the FDA action as a "sham." The consumer activist group claimed that under FDA plan it could be years before many useless drugs are removed from the Medicare and Medicaid market.

According to the Ralph Nader-affiliated research group, the drugs in question represent annual sales of between $200 million and $300 million to Medicare and Medicaid patients alone. Five states and the District of Columbia already bar Medicaid purchases of the drugs in question.

Included among the drugs targeted for removal by the FDA are Combid, prescribed for gastrointestinal disorders (estimated annual sales of about $25 million for some 3.1 million prescriptions); Equagesic, an alleged pain killer (estimated annual sales $22 million for 3.2 million prescriptions) and Mysteclin F, a prescribed antibiotic (estimated sales of $11 million on 1.5 million prescriptions).

Many of the drugs in question already were approved in 1962 when the federal govenment first invoked an efficacy rule in licensing drugs. That meant that all post-1962 drugs had to be proven efficient as well as safe before they were approved for use in the United States.

In reevalutating the drugs already on the market in 1962, the federal government labeled hundreds as "probably effective, possibly effective or ineffective." Three fourths of those drugs, about 500, have not been taken off the market.

But two thirds of those remaining on the market are now in a new category in which they are deemed ineffective, but are allowed to stay on the market because there are no other apparent cures for the disease they are prescribed to treat.

The HRS petitioned the FDA on May 5 to stop Medicare and Medicaid payments for all ineffective drugs, contending that the agency has been in violation of a 1972 court order to take those drugs off the market in any case.

The consumer group cited a letter from the FDA commissioner David Kennedy to the surgeon general, asking him to order a stop to the spending of federal funds on the ineffective drugs.

But the FDA says it must take the drugs through the administrative process before removing them, "affording manufactures an opportunity for a hearing before an administrative law judge."

Dr. Sidney Wolfe, director of the HRG, calls that process "a very shabby effort on the part of the government."

"This shows a reckless disregard for poor people," Wolfe said. He said that besides ignoring another 250 or so drugs that are not included on the HEW target list but should be, the Health, Education and Welfare Department action "will take years before even the drugs they do name are removed from the market."

Wolfe called on HEW to cut off all federal payments for the drugs, even while the administrative procedures go on.

"Most of these drugs have been around for 25 years already," he said. "If they havent't been shown to be effective up to now, they won't be."