PFIZER PLANS AZITHROMYCIN NDA FILING BY "EARLY SPRING," RESEARCH VP BLOOM TELLS ANALYSTS; ANTIFUNGAL DIFLUCAN IS IN "VERY LATE STAGES" OF FDA REVIEW
Pfizer is planning to file approval applications for the azalide antibiotic azithromycin "by early spring this year in the U.S. and abroad," VP of Central Research Barry Bloom, PhD, said Jan. 24. To a morning meeting with analysts at Pfizer's Manhattan corporate headquarters, Bloom said the "extended spectrum" semisynthetic oral antibiotic shows activity against gram negative/gram positive infections, and intracellular and spirochetes infections. He maintained that it is particularly effective against haemophilus influenzae respiratory problems. Azithromycin is a short course therapy with once-a-day dosing. It will compete against erythromycin and amoxicillin. The drug shows "much lower gastrointestinal side effects than erythromycin," Bloom contended. Pfizer will be seeking azithromycin indications for upper and lower respiratory tract infections (pharyngitis and sinusitis, and pneumonia and bronchitis, respectively); skin and skin structure infections; chlamydia and pediatric infections (otitis media). Azithromycin has had "excellent results" in treating chlamydia, Bloom told the analysts. A single 1 gm dose of azithromycin for the sexually transmitted disease proved more effective -- showing a 97% cured/improved rate -- than a seven-day course of doxycyline (Vibramycin), the current treatment of choice, he said. When asked during Q&A to compare azithromycin to Abbott's clarithromycin, Bloom said the Abbott azalide "clearly does not share the remarkable targeted delivery and pharmacokinetic properties of azithromycin. That's the short end...They are two very different compounds." Abbott filed the NDA for clarithromycin in December. Lilly is also in the azalide competition; however, Pfizer said it estimated that Lilly's dirithromycin is "a long way (one to two years)" behind in development. Pfizer plans NDA filings in the U.S. for two other antibiotics in the next year and a half: an oral version of Unasyn to be filed during the first half of this year; and Sulperazon (sulbactam/cefoperazone) in the second quarter of next year. Sulperazon already is marketed outside the U.S. and 1989 sales jumped 29% from $84 mil. to $108 mil. * Diflucan (fluconazole) is Pfizer's near-term pipeline project. NDA approval is expected this year. The drug is in "the very final stages of FDA review," Bloom told the analysts. The NDA for Diflucan was filed in February 1989 for prevention and treatment of systemic candidiasis and other fungal infections, and for acute and maintenance therapy against cryptococcal meningitis. The company also plans to apply for a pediatric indication, Bloom noted. Pointing to the critical need for more drugs to treat AIDS-related opportunistic infections, Bloom noted that 75% of AIDS patients suffer from oropharyngeal candidiasis, or thrush, far more than the 63% who contract Pneumocystis carinii pneumonia. Diflucan covers the spectrum of AIDS-related infections now being treated by nystatin, clotrimazole, ketoconazole and amphotericin B. For example, Bloom said, the cured/improved rate for thrush with Diflucan is 94% compared to 80% for clotrimazole; 87% for esophagitis compared to 53% for ketoconazole; 65% for oral fluconazole in cryptococcal meningitis compared to 68% for I.V. amphotericin B. The broad spectrum, synthetic antifungal, in both oral and I.V. once-a-day dosing forms, was launched in 1989 in Japan, the U.K., Italy, France and Germany. Revenues from the antifungal were $44 mil. last year, Pfizer said. The drug has been used to treat over 550,000 patients worldwide with only 1.5% of patients discontinuing therapy due to adverse side effects. Bloom also discussed two of Pfizer's cardiovascular drugs in late stages of review at FDA, the selective alpha blocker Cardura (doxazosin) and the calcium channel blocker Norvasc (amlodipine), as well as the selective serotonin reuptake inhibitor sertraline and the anti-inflammatory tenidap. Pfizer's heavy load of cardiovascular drugs pending at FDA prompted a question about the allocation of marketing resources. Asked whether both Cardura and the once-a-day antihypertensive Minipress XL (prazosin), which is also pending at FDA, would both be pursued, Bloom asserted: "You can rest assured that we plan to market both." He added: "It's an important opportunity for XL, and Cardura is widely applicable as a first line agent." Norvasc also has been waiting at FDA since 1987 but is marketed in the U.K. and Ireland. Other overseas launches are expected in 1990, Bloom noted. He did not offer any predictions for a U.S. launch, saying only that the FDA review of the drug "has proceeded smoothly." Pfizer filed the NDA for sertraline for depression in April 1988. Compared to Lilly's Prozac, Bloom said sertraline has "lower CNS arousal effects, like nervousness/agitation, anxiety and insomnia" and that there is no accumulation of the active metabolite. Like Lilly, Pfizer is also pursuing sertraline for obesity as well as for obsessive-compulsive disorders. Pfizer may be ready to report on a large scale head-to-head trial of sertraline and Prozac by the end of the year, but more likely in 1991, the company said. Asked if the dosing comparisons in the study were "loaded" in Pfizer's favor, Bloom replied sharply, "No." Also asked about sertraline's reportedly slower onset of action versus Prozac, he asserted: "I don't think there's very compelling data to suggest advantages of quick onset." Discussing the interleukin-1 and 5-lipoxygenase inhibitor tenidap (CP-66,248), Bloom said the drug would be "pioneering a new era of anti-inflammatory therapy." Tenidap, in Phase III, has shown "strong biochemical evidence of effects on disease mechanisms" of rheumatoid and osteoarthritis and is showing "increasing evidence of impact on disease progression," Bloom announced to analysts. Versus naproxen (Naprosyn from Syntex), it has been shown over a period of weeks to lower serum amyloid A, which is regulated by IL-1 and IL-6, and serum C-reactive protein, which is regulated by IL-6. IL-1 is associated with osteoarthritis; IL-6 with rheumatoid arthritis. In clinical comparisons, over four weeks, tenidap is proving comparable to naproxen in the treatment of rheumatoid arthritis, Pfizer said. Over a longer period (48 weeks), "tenidap patients continue to improve and get better," Bloom said. The company expects to report on its clinical trials at a scientific meeting in April in Washington, D.C.
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