VICKS VAPORUB CREAM FORMULATION REQUIRES CLINICAL TRIALS

VICKS VAPORUB CREAM FORMULATION REQUIRES CLINICAL TRIALS to assess safety and effectiveness, FDA Office of OTC Drug Evaluation Director William Gilbertson said in an Aug. 7 letter to Rich-Vicks parent Procter & Gamble. P&G submitted a proposed protocol to FDA in 1989 for in vitro studies of the cream formulation, a modification of Vicks VapoRub ointment. The company wrote FDA on July 1 requesting a meeting to discuss its plans to market VapoRub Cream based on those proposed studies, according to the letter. "The agency has...considered whether an in vitro study would be appropriate for your new VapoRub Cream product," the letter states. Both the Division of Bioequivalence and the OTC office medical staff concurred that "there are insufficient pharmacokinetics-pharmacodynamics data available to assess dose safety and effectiveness. Clinical trials are needed to assess the safety and effectiveness of your new VapoRub Cream product." The ointment version has been proposed as Category I (safe and effective) in the tentative final monograph for OTC cough-cold combination drug products published in August 1988. Because development of a final monograph "is not on our active worklist," the letter says, the agency is addressing cough-cold product questions instead through occasional "feedback" letters. FDA issued a similar feedback letter to O'Connor Pharmaceuticals in April, the letter notes. "You can ascertain from our letter to O'Connor Pharmaceuticals that the agency has reconsidered previous recommendations it made for that specific product and that the agency does not currently consider an in vitro study adequate to demonstrate effectiveness." O'Connor has been seeking to demonstrate bioequivalence to VapoRub ointment based on in vitro studies to support a Category I antitussive clain for its product Vaporizer in a Bottle. According to the letter, P&G's in vitro protocol was designed to show that the concentrations of the VapoRub active ingredients (menthol, camphor and eucalyptus) in air for the cream base product provide the same therapeutic levels as those provided in VapoRub ointment. After reviewing the proposed protocol, the Division of Bioequivalence "determined that it would not readily accept the data from the aluminum block study for anything other than as a quality control measure for the two formulations unless a clear in vitro and in vivo correlation has been shown to exist." "A heated aluminum block is not the skin and given the fact that, in general, creams are absorbed faster than ointments, it would be difficult to quantitate this physiological process with an aluminum block," FDA continues. "In order to rigorously address questions related to loss, mass balance needs to be done and this is not possible because none of the components are absorbed into the aluminum block." FDA also questions data presented from a study of the release of the individual product components following application to polyethylene dishes and exposure to air. Data obtained via the proposed sampling method "would be difficult to interpret," the agency says. The letter suggests that P&G "consider submitting a clinical protocol for review," or, alternatively, initiate studies "at your own risk." FDA will be able to meet with the company after Oct. 1, the letter says.