THEOCHRON WILL RETAIN "AB" RATING FOR 12-HOUR DOSING, FOREST CLAIMS

THEOCHRON WILL RETAIN "AB" RATING FOR 12-HOUR DOSING, FOREST CLAIMS, regardless of the outcome of a pending 24-hour dosing bioequivalence study. In an Aug. 10 statement to "The Pink Sheet," Forest Labs President Howard Solomon maintained that Forest's "longstanding 'AB' bioequivalence rating," indicating therapeutic equivalence to Schering-Plough/Key's Theo-Dur, "for B.I.D. dosing for Theochron 300 mg is not in any jeopardy whatsoever." The company was responding to what it considers "certain misleading conclusions" in "The Pink Sheet" (Aug. 8, p. 8). The article focuses on FDA's response to two petitions regarding bioequivalence requirements for approved generic drugs in light of changes in the brandname product's label. FDA's "Orange Book" (Approved Drug Products with Therapeutic Equivalence Evaluations) currently notes in a "special situations" section: "Because Theo-Dur is approved for both once-daily and twice-daily dosing," it is "important to be aware that the therapeutic evaluation was made on the basis of 12-hour dosing intervals" and therefore "does not apply to once-daily dosing intervals." The agency's letter to Key states that if the generic drug sponsor does not supply the additional data "in a timely manner" or if the data "do not rebut the presumption of clinical differences," FDA will delete the "Orange Book" notation "and recommend that the drug product is not therapeutically equivalent." FDA's letter, "properly interpreted, does not indicate that the B.I.D. bioequivalence rating is dependent on once-a-day dosing approval," Solomon contended. Solomon maintained that, in such a scenario, without additional data to support once-daily dosing, the "Orange Book" would be amended to indicate that Theochron is not therapeutically equivalent only for once-daily dosing. Nonetheless, Forest is conducting a study to support Theochron bioequivalence to Theo-Dur in once-daily dosing. Earlier this year, after internal discussions indicated that FDA would respond to the petitions by requiring labeling of listed drugs and AB-rated generic drugs to agree (but before the formal response), the agency advised Forest to conduct studies to confirm Theochron's bioequivalence in 24-hour dosing and in administration with food. FDA approved Forest's food study in June and the 24-hour dosing study will be completed "in the near future," Solomon said. The food study "again confirmed the bioequivalence of" Theochron to Theo-Dur, he said.