ZOVIRAX' OTC SWITCH APPLICATION FOR GENITAL HERPES
This article was originally published in The Tan Sheet
ZOVIRAX' OTC SWITCH APPLICATION FOR GENITAL HERPES could be filed by the end of 1993, Burroughs Wellcome USA President Philip Tracy told securities analysts in New York City on March 25. "In the U.S., our clinical program is under way to collect data on which to base an application for FDA approval of OTC Zovirax in oral form for the management of recurrent genital herpes," Tracy said. Burroughs Wellcome has been in contact with FDA in developing the application, he added, and is encouraged by the agency's response. "We intend at the moment to submit an NDA later this year" for the oral dosage form of the prescription antiviral agent, Tracy noted. "There may still be some studies ongoing at the time [we file], but we think we'll have the bulk of the package ready by the end of the year -- then it will be a question of how long the FDA takes to review the NDA." A topical dosage form of Zovirax is already approved as an OTC treatment for cold sores in six countries overseas, Tracy noted. Tracy said the company will build on the antiviral drug's "track record" of "safety and efficacy over its ten years of prescription usage." He added that the company is "hopeful that this track record will in fact expedite FDA's review and approval of the switch of the product to OTC status." In addition, Burroughs Wellcome has conducted large epidemiological studies involving 30,000 to 40,000 patients to support the application. The company plans to address two of FDA's concerns with making Zovirax available OTC -- the potential for viral resistance developing as a result of the switch and the ability of patients to distinguish recurrent herpes from other conditions. Burroughs Wellcome USA VP-Research, Development and Medical David Barry said the company is testing for viral sensitivity "in some very specific settings that the FDA wanted . . . involving just a couple of hundred patients and isolates." Barry noted that Burroughs Wellcome has examined "about 12,000" viral isolates for resistance to Zovirax since the drug was discovered. Another ongoing trial, Barry explained, will test patients' ability to distinguish a recurrent genital herpes episode from other ulcerative genital diseases, such as syphillis or chancroid. Based on results from a pilot study, "we believe strongly that patients who already know they have genital herpes can easily differentiate a recurrence of their herpes from a new infection," Barry said. FDA has demonstrated its willingness to approve products for OTC use to treat recurrent conditions that initially were diagnosed by a physician. In 1991, the vaginal candidiasis treatments Gyne-Lotrimin (Schering-Plough) and Monistat-7 (Johnson & Johnson) were switched to OTC marketing with labeling directed at women who in the past have been diagnosed with a yeast infection. In the U.S., prescription Zovirax is approved for treatment of genital herpes, shingles and chicken pox. In the first six months of fiscal 1993 (ended Feb. 27), U.S. sales grew by 21% (excluding currency effects), Tracy reported. Worldwide sales were $ 568 mil., up 17% excluding currency effects. The U.S. patent on Zovirax expires in 1997, Tracy noted. The first worldwide patent expiration comes this year in Germany, where Zovirax has been available as an OTC since July 1992 under a marketing deal with Hoechst. Tracy cited Burroughs Wellcome's experience with OTC Zovirax in New Zealand as an example of the potential commercial impact of switches elsewhere. After flat sales of prescription Zovirax for the previous 18 months, Tracy said, sales in the most recent six months were up 31%. Another, more distant OTC switch candidate for Burroughs Wellcome could be the nonsedating antihistamine Semprex (acrivastine). An NDA for a prescription acrivastine/pseudoephedrine combination is scheduled for review by FDA's Pulmonary-Allergy Drugs Advisory Committee on April 26, Barry noted. "We believe it has a . . . unique advantage of not having [the] cardiotoxicity" problems associated with other nonsedating antihistamines such as Marion Merrell Dow's Seldane and J&J's Hismanal, Barry said. He noted that the product is going OTC in some European countries. Burroughs Wellcome will likely have a partner for OTC marketing of Zovirax in the U.S. as part of a larger OTC alliance, Tracy indicated. Worldwide OTC product sales declined 3%, excluding currency effects, to $ 208 mil. ((BRITISH POUND)135 mil.) in the first half of fiscal 1993, Tracy reported. Volume declined by 7%, with a 4% price increase making up some of the difference, he said. In contrast, Burroughs Wellcome half year sales were up 11%, excluding currency, to $ 1.58 bil. ((BRITISH POUND)1.02 bil.). Prescription drug sales were up 13% excluding currency effects, with price increases contributing 1% of the increase. "To some extent this lack of growth in our OTC business was expected, based on particularly exceptional strong growth during the same period last year of some 32% and also highly difficult conditions in this six months when we did not have the same cough/cold and flu season this year," Tracy explained. Nevertheless, the poor performance of the OTC business "again points to the desirability of exploring some sort of strategic alliance in order to get ourselves much greater critical mass in this important market," Tracy said. "We have been talking to a number of parties in the course of the last 12 months." Prescription Zovirax is comarketed in the U.S. by American Home Products subsidiary Wyeth-Ayerst for the chicken pox indication.
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