Generic but equal, says the FDA

The Food and Drug Administration endorsed the equivalency of generics and brand-name pharmaceutical products in a letter sent to physicians and state boards of pharmacy in January.

In the letter, Stuart Nightingale, M.D., associate commissioner for health affairs, addressed the safety and efficacy of switching a brand-name product with an FDA-designated therapeutically equivalent generic product. A flurry of queries from state legislators uncertain of the agency's position on the issue inspired the FDA to issue a formal statement.

States are debating this issue as a result of competition between brand-name manufacturer DuPont Merck, Wilmington, DE, and generic manufacturer Barr Laboratories, Ponoma, NY. DuPont Merck's Coumadin® has been replaced in some instances by Barr's generic warfarin since Coumadin lost its patent protection last year. As a result, DuPont Merck advocated a bill that would require physicians' approvals of drug substitutions.

The Washington-based Pharmaceutical Research and Manufacturers of America expressed its support of such legislation.

"Until recently, the FDA allowed a deviation of plus or minus 20% in bioequivalency. That's not much of a deviation but there have been some cases where, because of the delicacy of a disease, a change from one drug to another has caused a reaction," said Jeff Trewhitt, vice president of communications at PhRMA. Epilepsy, he continued, is a good example of a disease in which subtle changes in medication might produce noticeable results.

The FDA sees the issue differently, and issued its statement based on its research data. "To date, there are no documented examples of a generic product manufactured to meet its approved specifications that could not be used interchangeably with the corresponding brand-name drug," Nightingale wrote.

Patients may report greater incidence of decreased efficacy or increased toxicity after substitutions because they pay more attention to their symptoms when such changes are made, Nightingale continued, but clinical investigations of such claims don't support the reports. In one instance, he wrote, the FDA tested more than 400 samples of 24 marketed brand-name and generic products and the found that all the products met the agency's established standards of purity and quality.

Brand-name products and therapeutically equivalent generic products are listed in the FDA's "Approved Drug Products with Therapeutic Equivalence Evaluations," also known as the "Orange Book." PR