The head of the nation’s largest trade group for the specialty pharmacies known as compounders said he will support legislation requiring pharmacies that operate like drug manufacturers to register with the Food and Drug Administration and be subject to stricter standards enforced by the agency.

The new position by the International Academy of Compounding Pharmacists follows a Washington Post investigation that showed 15 of the nation’s largest compounding pharmacies, which make custom-ordered medications, operate like drug manufacturers but do not have to register with the federal government or follow the same safety laws.

The Post also reported that shoddy equipment and unsanitary conditions at some of these firms had caused patient illnesses and deaths long before an October meningitis outbreak that was linked to tainted steroids made at a Massachusetts-based compounding pharmacy. Congress is investigating compounding pharmacies after steroid shots made at the New England Compounding Center were linked to the outbreak, which killed 47 people and sickened another 660.

“We want to enable and clarify for the FDA that those businesses that are involved in the manufacturing of compounded drugs, regardless of size, be regulated like drug manufacturers,” said David G. Miller, the academy’s executive vice president.

Miller and his 2,700-member group have traditionally argued that all pharmacies should fall under the purview of state pharmacy boards, not the FDA, and fought efforts in 2007 to shift primary oversight from the states to the federal government.

Here are basic steps a compounder could follow to make a drug.

On Thursday, Miller said he now wants to see FDA registration for what he describes as compounding manufacturers and supports giving the agency the power to enforce safety standards for these firms.

“They’re singing a different tune,” said a congressional staffer who is knowledgeable about Capitol Hill discussions concerning the FDA’s role in regulating compounders.

Officials who represent state regulators say the change reflects a broader shift in momentum. There is now agreement within the industry that additional oversight is needed for pharmacies that go beyond the traditional role of filling prescriptions for individual patients.

“So what you’re seeing now is people jumping on the bandwagon,” said Carmen Catizone, executive director of the National Association of Boards of Pharmacy, which represents the state pharmacy regulators.

Industry trade groups want to help define the new category that would be subject to FDA regulation so they have a say over how it would affect their members, Catizone said.

David Ball, an academy spokesman, said the shift in the organization’s position has not been previously disclosed and has been shaped by discussions over the past few months that made it “increasingly clear” that “there is an evolving marketplace of non-traditional manufacturing.”

FDA Commissioner Margaret A. Hamburg told Congress three months ago that some “non-traditional” compounders should be placed into a special category for stepped-up enforcement, but she said oversight could be carried out by either her agency or state pharmacy boards.

Under existing laws, pharmacies register with and are licensed by state boards of pharmacy, not the FDA. Drug manufacturers must register with the FDA, and their products must be approved by the agency.

The proposal to create a third category, which recognizes that some compounders are a hybrid of the pharmacy and drug manufacturing world, is being debated on Capitol Hill.

Miller said the defining factor for this new category should be whether pharmacies are making and marketing unique compounded medications. The size of the operation shouldn’t matter, he said.

But most compounding experts said the greatest safety concerns are with big compounders that make doses of medication in bulk without a patient prescription and then ship their products across state lines to hospitals and clinics.

“Size does matter,” said Mary K. Pendergast, a former FDA deputy commissioner and former associate chief counsel for enforcement at the FDA. “But just where you draw the line is complicated.”

Pendergast and other compounding experts said a subset of the larger compounders pose the greatest risk and thus require the greatest scrutiny. Some of the firms use non-FDA-approved drugs as key ingredients in their products. Also, many of the drugs are not dispensed in pill form but are administered intravenously or injected directly into patients.

The New England center, for example, used non-FDA-approved drugs to make the contaminated methylprednisolone acetate steroid injections that are tied to the meningitis outbreak.

Sarah Sellers, executive director of the Center for Pharmaceutical Safety, who met with congressional staffers Wednesday and Thursday, said her greatest concern is that a new enforcement system would be set up for compounders based on a model that assumes they are using FDA-approved ingredients to make their products.

“When people use FDA-approved ingredients, built into that are good manufacturing practices. But there is an entire group of compounding pharmacies that are not using FDA-approved drugs. I’m concerned they will end up creating a ‘good manufacturing practices light,’ ” Sellers said.