CHOLYBAR NOT "FULLY SUBSTITUTABLE" FOR QUESTRAN

CHOLYBAR NOT "FULLY SUBSTITUTABLE" FOR QUESTRAN powder, FDA agrees with Questran manufacturer Bristol-Myers in a March 9 letter. The Drug Advertising & Labeling Division's Thomas Cavanaugh wrote: "We concur with your observation" that the phrase "fully substitutable for Questran powder" in a Parke-Davis journal advertisement "could be misleading and is probably inappropriate." The agency told Parke-Davis of its reservations about the ad in a March 10 letter. FDA's objection represents a change of position. The agency acknowledged its shift in the letter to Bristol-Myers. "Because FDA did not object to the ad phrase 'fully substitutable for Questran powder' when it reviewed the proposed initial campaign . . . FDA will notify Parke-Davis that [it] has changed its opinion." The agency added that Parke-Davis "will be given a reasonable time (90-120 days)" to delete the phrase from future ads "before any regulatory action is taken." Bristol-Myers complained about the Cholybar ad in a Feb. 17 letter. The complaint followed a citizen's petition in which the Questran manufacturer contended that the products are not therapeutically equivalent and asked that the Cholybar ANDA approval be withdrawn pending further studies ("The Pink Sheet" Jan. 2, T&G-9). In its letter to Bristol-Myers Regulatory Assistant Director Marygayle Ritzert, FDA explained that it still considers Cholybar "bioequivalent to Questran powder" with respect to the active ingredient. FDA said it "regards each gram of cholestyramine made available in Cholybar to be therapeutically equivalent to each gram of cholestyramine made available in Questran powder." Nonetheless, "because one product is a bar and the other product is a powder, they are not AB rated," the letter continues. "Obviously, a pharmacist who on his own initiative substitutes one product for the other would, to say the least, gain the patient's attention. The same would hold true whenever one dosage form, e.g., a suppository, is substituted for another, e.g., an oral liquid." The lack of full substitutability applies to pharmacists but not doctors, FDA said. "Although the physician may authorize the pharmacist to replace Questran with Cholybar -- or vice versa -- the pharmacist may not do so in the absence of such authorization."