HRG IODOCCHLORHYDROXYQUIN REMOVAL PETITION TO FDA

HRG IODOCCHLORHYDROXYQUIN REMOVAL PETITION TO FDA is based on a 1984 University of Nebraska dog toxicity study which demonstrated that "significant toxicity can occur from application of iodochlorhydroxyquin," the Health Research Group (HRG) maintained in a June 24 filing to the agency. "The (study's) authors concluded that 'long-term application by an occlusion technique, as might be experienced with diaper dermatitis, can result in sufficient absorption to produce hepatoxicity,' " the letter stated. "The doses received by the dogs, approximately 17 mg/kg per day, is close enough to the 9 mg/kg per day or more that a baby might easily receive to be of serious concern." The HRG petition requests the removal of all Rx and OTC drugs containing iodochlorhydroxyquin, also known as clioquinol, from the market, maintaining that they are "dangerous to infants and adults." The ingredient is found in Ciba-Geigy's OTC product Vioform, as well as in the firm's Rx drug Vioform HC (hydrocortisone). Other Rx products containing iodochlorhydroxyquin include Arlo's Pricort Cream and Pricort Lotion, Saron's HCV Creme, Pedinol's Pedi-Cort V Creme and Miles' Nystaform Ointment, in addition to generic products. The Nader group's letter notes that these antifungal/anti-infective drugs, which are applied directly to the skin, are frequently used for the treatment of diaper rash and other skin problems in infants and children. "Because there is significant and rapid absorption of iodochlorhydroxyquin through the skin," the letter states, "and because of the known toxicity of iodochlorhydroxyquin in animal skin absorption experiments at doses similar to those that infants may get, all products containing this ingredient should be removed from the market." I he petition claims that there is substantial percutaneous absorption of the ingredient in humans and dogs and that amounts of the drugs not excreted from the body are stored in tissue. It further notes that animal studies suggest that toxicity may occur at fairly low levels of exposure, "levels close to those an infant may receive." Because iodochlorhydroxyquin is applied topically, the drug does not pass through the liver to be detoxified before entering the bloodstream and can therefore collect in various organs, the petition maintains. According to the HRG, an oral form of iodochlorhydroxyquin was previously used to treat travellers' diarrhea and acrodermatitis enteropathica, but was taken off the market in the U.S. after it was linked to over 10,000 cases of subacute myelo-optic neuropathy in Japan and other countries. FDA has been moving against Vioform HC, a DESI drug, but for reasons of efficacy rather than safety. Claiming that the drug is less than effective, the agency planned to hear Ciba-Geigy's evidence to the contrary last April at a DESI hearing before Administrative Law Judge Daniel Davidson ("The Pink Sheet, Dec. 3 1984 T&G-4). That hearing was postponed, and has been rescheduled for November.