MARION MERRELL DOW’s SELDANE OTC IS "ON HOLD"

MARION MERRELL DOW's SELDANE OTC IS "ON HOLD" as MMD and FDA work on "the mechanism" for designing a study to address concerns about cardiovascular side effects associated with the nonsedating antihistamine terfendine. MMD President Fred Lyons told Mabon Nugent's fifth annual research conference Dec. 5: "We, with FDA, have agreed to put on hold [OTC Seldane] until we identify the issues" and extent of possible episodes of torsades de pointes prolonged QT intervals and/or ventricular arrhythmias associated with the product. Lyons noted the difficulty of creating a protocol to investigate the cardiovascular side effects. For example, a "2,500 patient study" is inadequate to assess cardiovascular events from Seldane OTC when the incidence of torsades de pointes reported for the prescription version has been about "one in four million cases," he stated. MMD believes the answer "may be through an epidemiology approach," Lyons added, noting that MMD is "working now with FDA on the mechanism." Following FDA's Pulmonary-Allergy Drugs Advisory Committee's review of prescription Seldane and the issue of torsade de pointes ("The Pink Sheet" June 18, p. 6), Marion Merrell Dow has relabeled Seldane. The revised labeling includes a discussion of overdose and cautions against terfenadine's use by people with impaired liver function. The company believes that Seldane patients who also were taking ketoconazole or had cirrhosis of the liver metabolized Seldane differently, thus resulting in some incidents of overdose. The company also issued a "Dear Doctor" letter on possible Seldane cardiovascular side effects. While the committee did not formally recommend a "Dear Doctor" letter, three members strongly suggested that one be sent to advise physicians of the labeling changes. The adverse publicity from the June advisory committee meeting and the subsequent "Dear Doctor" letter resulted in a "short-term" decline in Seldane prescriptions, Lyons acknowledged. However, September-October script data shows that Seldane numbers are "exceeding pre-June growth rates," he noted. The spillover from Seldane's appearance before the agency committee does not appear to have affected MMD's expectations for the approval of the Seldane-D antihistamine-decongestant prescription product. "We hope for approval in the not too distant future," Lyons said. There "are no pending issues on that."