WHEELING, W.Va., July 17 — The FDA has clarified how it plans to regulate drug additives intended to thwart counterfeiting and make it easier for authorities, providers, and consumers to spot fake prescription drugs.

The agency issued a draft guidance to industry this week covering anticounterfeiting measures that legitimate manufacturers might use to authenticate their products.
In particular, it addresses so-called physical-chemical identifiers — unique, hard-to-duplicate, readily detected additives that would distinguish drugs made at approved facilities from cheap, unlicensed fakes — placed on or in pills and capsules.
The scale of counterfeiting in the U.S. is unknown, but drug manufacturers take it very seriously.
At a Washington seminar last month, a Pfizer security official said he was recently asked to authenticate a batch of products ostensibly produced by the company and shipped from overseas.
They were addressed to U.S. residents and had arrived at a mail facility over the course of a week.
Of 250 packages labeled as Viagra (the company’s formulation of sildenafil for erectile dysfunction), all turned out to be counterfeit, he said.
At the same seminar, an FDA enforcement official said the agency had opened 56 new counterfeiting investigations in 2008.
“Drug counterfeiting is a serious public health concern,” FDA Commissioner Margaret Hamburg, MD, said in announcing the guidance.
She said the agency wanted to work with industry “to help ensure that consumers are not exposed to products containing unknown, ineffective, or harmful ingredients.”
Much of the guidance is unsurprising, such as a recommendation that additives not be allergenic or used at unsafe levels.
The agency said it expects that manufacturers would generally prefer identifiers based on existing food additives or colorants, or on drug excipients with well-established safety profiles.
“To minimize toxicological risk, FDA recommends using permissible direct food additives, including those affirmed as generally recognized as safe or those ingredients listed in the FDA Inactive Ingredient Guide,” according to the guidance.
For additives considered unlikely to cause adverse effects in patients taking the drugs, companies may simply report the addition in an annual report rather than seek prior approval, the FDA said.
Companies will also be able to use their own discretion in deciding whether to list the identifiers as ingredients on the label.
Manufacturers might wish to do so when the identifier is visually obvious, the agency said, so that healthcare providers and patients know to look for it.
However, the guidance noted, such labeling changes will be subject to the FDA’s usual reporting and approval process.
In all cases, manufacturers will need to document the identifier’s chemical composition, how it will be incorporated in solid oral drugs, and at what concentration.
They will also need to verify that it doesn’t alter the drug’s biological behavior in any way.
Technically, the FDA’s guidance documents are merely suggestions, representing the agency’s “current thinking” on issues. But companies usually follow them closely.
The agency will take comments on the draft through Oct. 7, after which it will release a final version.