GLAXO's ZANTAC v. TAGAMET SUPERIORITY CLAIMS CRITICIZED BY FDA; FIRM APPEALS TO HAWAII AND CALIFORNIA DRUG CMTES. FOR INCLUSION OF ZANTAC IN STATE FORMULARIES

Glaxo's claims of Zantac superiority to Tagamet in recent letters to Hawaii and California Medical Therapeutics and Drug Advisory Cmtes. was criticized by FDA in a four page notice to the firm. FDA Drug Advertising and Labeling Div. Director Louis Morris detailed FDA's objection to a Nov. 26, 1985 letter Glaxo sent to the two advisory cmtes. regarding inclusion of Zantac in California and Hawaii state formularies. Morris told Glaxo President Joseph Ruvane: "There are no adequate and substantial data of which we are aware that shows Zantac is superior in overall effectiveness and/or safety." Glaxo told the cmtes. that Zantac has "greater efficacy in both acute ulcer healing and prevention of ulcer relapse than cimetidine"; has a superior safety profile to cimetidine; has a higher ulcer healing rate; and is more cost-efficient. Specifically, Glaxo stated that Zantac achieves ulcer healing in "reportedly up to 75% of patients not responding to cimetidine." FDA responded: "That may be true, but it is also true from what we know that cimetidine heals patients who fail to respond to Zantac. Do you have data to show that this converse is not true?" Glaxo also said the "recommended therapy duration for cimetidine . . . is four to six weeks" while with Zantac "most ulcers heal within the recommended therapy duration of four weeks." FDA stated that in fact "the healing rates at four weeks for both drugs are comparable." With regard to cost-efficiency of treatment, Glaxo stated in its letter that "although the cost of Zantac daily treatment has averaged 14.5% more than that of cimetidine over the past two years, the increased efficacy of Zantac therapy more than cancels this out, considering the expense of dealing with failed patients (hospitalization, surgery, alternative therapies, etc.)." The firm added that "there is also the freedom with Zantac from the cost of expensive laboratory monitoring which should be performed on some cimetidine-treated patients." FDA stated, however, that "with the exception of patients on warfarin-type drugs, cimetidine does not seem to require any more extensive laboratory monitoring than Zantac patients." Glaxo also maintained that unlike Zantac, cimetidine interferes with the hepatic metabolism of other commonly administered drugs. Further, Glaxo said "the reported incidence of mental confusion is lower for Zantac" than for cimetidine. In addition, the company said "experience with Zantac indicates that unlike cimetidine, Zantac does not possess anti-androgenic activity with consequent effects on male sexual function. Impotence and gynecomastia have in fact reversed when Zantac has been substituted for cimetidine." FDA responded that the data supporting cimetidine "alleged interactions" with other drugs "has been questionable at best in many cases. In addition, we have seen little data showing any clinical significance to most of these." The agency noted that Glaxo failed to mention that Zantac approved labeling states "there have been isolated reports of drug interactions which suggest that Zantac may affect the bioavailability of certain drugs by some mechanism as yet unidentified." With regard to anti-androgenic effect, FDA said Glaxo did not point out that cimetidine labeling states that the incidence of reversible impotence "did not differ significantly between the Tagamet and placebo groups." The agency said a "very similar" statement appears in Zantac labeling. The agency also objected to Glaxo's claim that Zantac prevents ulcer relapse, since it is an unapproved indication. FDA emphasized that Glaxo has been recalcitrant in correcting its promotional claims for Zantac. The agency concluded: "All of these points have been discussed repeatedly with your firm and as expressed in our letters of Feb. 13, 1985 and Sept. 11, 1985. We apparently have had little success in achieving voluntary correcting of these advertising and promotional practices on the part of your firm." FDA said any future use of the claims or concepts outlined in the letter "will result in the initiation of formal regulatory action against your firm." FDA sent copies of its letter to Glaxo to the Hawaii and California Medicial Therapeutics and Drug Advisory Cmtes. and to FDA staff covering federal state relations so the staff could forward the letter to other state formularly boards. California and Hawaii state formulary cmtes. have not yet decided on the addition of Zantac to their formularies. However, Glaxo said the California advisory cmte. has recommended the drug for inclusion in the California formulary.