NITROGLYCERIN PATCH ADVERTISING MUST INCLUDE "REVISED DOSAGE INFORMATION"

NITROGLYCERIN PATCH ADVERTISING MUST INCLUDE "REVISED DOSAGE INFORMATION" on tolerance and revised labeling sections in the brief summary, FDA Drug Advertising and Labeling Division Acting Director Ken Feather said in a Jan. 19 letter to marketers of nitroglycerin patches. "We have taken the position that the 'double boxed emblem' constitutes a 'special Note' which must be included in the 'brief summary' of all advertisements for these products," the agency said. The letter notes that current labeling for nitroglycerin patches "has been revised to reflect concerns developed from recent studies conducted to address a reported 'tolerance' effect." The result is changes in sections of the labeling as well as inclusion of a "double boxed emblem" at the top of labeling that reads "Revised Dosage Information," Feather said. FDA's Cardio-Renal Drugs Advisory Committee unanimously agreed at a meeting last year that nitrate labeling should be revised to state that intermittent dosing for angina reduces tolerance to the drug that is developed with continuous dosing ("The Pink Sheet" Jan. 30, 1989, p. 5). The "double boxed emblem" calling attention to the revised labeling will be required in labeling only for six months. During that period, all advertisements that use a brief summary must carry the "special note" about revised dosing. In addition, the brief must include the revised sections of labeling -- the Dosage and Administration, Clinical Pharmacology, and Overdosage sections. The revised Dosage and Administration section of Riker's Minitran patch product, for example, reads: "Although the minimum nitrate-free interval has not been defined, data show that a nitrate-free interval of 10-12 hours is sufficient. Thus, an appropriate dosing schedule for nitroglycerin patches would include a daily patch-on period of 12-14 hours and a daily patch-off period of 10-12 hours." Minitran's Clinical Pharmacology section notes: "In one well-controlled clinical trial, subjects receiving nitroglycerin appeared to exhibit a rebound or withdrawal effect, so that their exercise tolerance at the end of the daily drug-free interval was less than that exhibited by the parallel group receiving placebo." FDA sent the letter and guidance to the following companies: Bolar, Ciba-Geigy, Riker, Schering, Searle, Warner-Chilcott and Wyeth-Ayerst.