PCMX ANTIMICROBIAL ABSORPTION STUDIES AND COMPUTER SIMULATION

PCMX ANTIMICROBIAL ABSORPTION STUDIES AND COMPUTER SIMULATION show no accumulation fo the drug in the body, Wallace Guess, MD, University of Mississippi, told FDA representatives at an OTC feedback meeting June 19. A consultant for Fort Worth, Texas-based Dexide, which markets the PCMX (chloroxylenol) surgical hand scrub Ultradex, Guess maintained that subchronic accumulation studies, including a computer simulation model recently completed by the Drug Dynamics Institute for Dexide, show that there is no accumulation either of chemical or of injury." Further long-term safety studies, therefore, are not necessary, Guess asserted. "Subchronic studies are designed to show you if you need to do a chronic study," Guess said. "Since the subchronic studies show [that there is no accumulation], there is no point in doing a chronic two-year study," he maintained. "You are not going to find much it seems to me that you have not already found in the chronic study." FDA's postion has been that the data received so far to support the safety of PCMX for long term use as a surgical hand scrub or health care personal hand wash are not adequate. The data should include a two-year rat study, the agency has maintained, because the topical antimicrobial agent is intended for long-term, repeated daily use. Hand scrub marketers, including Dexide and Ferro Corp., petitioned FDA to move the ingredient to Category I from CategorV III where it was placed in the 1978 OTC Antimicrobial Tentative Final Monograph. Dexide Science and Technology VP Mike Garabedian, PhD, who presented the results of the computer absorption model at the meeting, told the FDAers that his company would be willing to undertake a long term study, but questioned whether the study would serve any purpose. "I tnink the issue is: what would you find if you [did the study]?; and do you have that information now?" Garabedian said. "I am persuaded. . .that you wouldn't get any more information than you've got." Based on the model's confirmation of the other data, Garabedian continued, "we feel that there is no evidence for any indications that accumulation in the blood can occur, even under greatly exaggerated conditions." FDA OTC Drug Evaluation Div. Director William Gilbertson, PharmD, noted that Guess' assessment of the data was different from that made by the Antimicrobial II panel, which under Guess' chairmanship had reviewed the data and found it incomplete. Asked by Gilbertson what had changed his mind, Guess noted that some of the data, including the computer model, had not been available to the panel. In addition, "we had not had all of this put in one complete package," he said. Asked if he would have a different view of chloroxylenol as an OTC panel member today, Guess responded: "Let me put it this way, if (OTC panel staffer) Lee Geismar had sent this to me and said that I want you to evaluate this, this is the very format and type of report I would have written." Dexide consultant Mary Bruch asserted that the "emphasis of the panel on the safety factor calculation in the original report. . .really was the bar soap," and "would not be used to characterize" the surgical hand scrub.