THERAPEUTIC EQUIVALENCE RATING IN FDA's "ORANGE BOOK"

THERAPEUTIC EQUIVALENCE RATING IN FDA's "ORANGE BOOK" does not affect the rights of a mfr. or reflect on a product, attorney Jonah Shacknai (D.C. firm Royer, Shacknai & Mehle) stated in a supplement to a citizen petition filed by the firm in January. Shacknai said comments submitted to FDA by the Generic Pharmaceutical Industry Assn. (GPIA) and Forest reflect a "fundamental misunderstanding" of the petition. Shacknai asserted that the petition requests merely "that FDA not rate as 'therapeutically equivalent' any two drugs which do not meet the 'sameness' requirement of the [Waxman/Hatch] Act (e.g., drugs whose labeling differences are not among those permitted under the 1984 Act for drugs which are otherwise the 'same' as the listed drug) and, in the case of post-1984 ANDA'd drugs, approve such drugs under an ANDA only if they have first been the subject of an ANDA-suitability petition." Shacknai stated that "the presence or absence of a 'therapeutic equivalence' rating in the "Orange Book" affects no rights of any mfr. Nor would a change in a 'therapeutic equivalence' rating, e.g., from an 'A' rating ('therapeutically equivalent') to a 'B' rating ('not therapeutically equivalent') or the elimination of a product's rating altogether even reflect adversely on the product." However, Shacknai added, by ensuring that "drugs whose conditions of use differ from one another not be rated 'therapeutically equivalent,'" FDA "would help avoid the significant adverse reactions and thereapeutic failures that may occur when drugs are substituted for each other for conditions for which they are not 'therapeutically equivalent.'" GPIA argued that the Waxman/Hatch law's definition of bioequivalence recognized that there may be situations where the generic drug and "listed" drug are equivalent despite labeling differences. Shacknai responded that the Act "reserves the ANDA-suitability petition procedure for drugs which are materially different from the listed drug." He said "under current FDA practice such drugs would not be rated in the Orange Book as 'therapeutically equivalent' to the listed drug." In its comments, Forest maintained that the addition of a once-a-day dosage regimen to Key's Theo-Dur should not alter the therapeutic equivalence rating of Forest's Theochron that was designated by FDA in 1983. Shacknai said "the time at which a rating was granted a drug -- pre-1984 Act vs. post-1984 Act -- has no bearing on the question whether it is 'pharmaceutically equivalent' and 'bioequivalent' to another drug; nor does the existence or non-existence of another drug which might or might not be termed a 'listed' drug; nor does the time at which a new dosing schedule was approved for one of the two drugs; nor does the size of the market for the drug with the new dosing schedule."