PFIZER SEEKS EXCLUSIVITY FOR ZOLOFT THROUGH 2005: ROLL CALL OF REQUESTS FOR PATENT EXTENSIONS BASED ON LENGTHY FDA REGULATORY REVIEW PERIODS
Pfizer is asking the Patent & Trademark Office for an extension of over three years for the patent on the antidepressant Zoloft (sertraline), hoping for protection until 2005. The patent extension request was documented in a May 1 Federal Register statement. Pfizer received a patent for sertraline in 1985 and FDA approval in December 1991, giving Zoloft about 11 years of marketing exclusivity. If Pfizer receives the extension, Zoloft would enjoy branded exclusivity four years beyond patent expiration for the first serotonin reuptake inhibitor, Eli Lilly's Prozac. Lilly received its initial patent for Prozac in 1982; with a two-year extension granted in 1988, the drug will remain protected until at least 2001. However, Prozac exclusivity could last another two years until 2003, when a subsequent use patent (4,590,213) for "a method of treating anxiety in a human subject in need of such treatment" expires. Pfizer's request for a Zoloft patent extension was one of ten published by FDA from the first of May through June 12 according to the Waxman-Hatch Act procedures. The Zoloft request is the third longest among the applications published over the last five weeks (see chart below). The total regulatory review period for Zoloft approaches 11 years, with approximately one third of that time devoted to the NDA review. Pfizer previously has received extensions for Diflucan (1,126 days) in 1990 and for Cardura (two years) in 1991. Diflucan (fluconazole) goes off patent in October 2003, and the extended Cardura (doxazosin) patent expires on Feb. 12, 1999. Takeda is also seeking protection through Waxman-Hatch, requesting a patent extension until 2005 for its DTP vaccine Acel- Imune (marketed by Lederle). Takeda also has applied for and received a second patent for Acel-Imune on March 3, 1992, three months after the product was approved. Thus the product has potential patent protection lasting until the end of the first decade of the next century (2009). In a request for Maxaquin (lomefloxacin), Hokuriku asks for 1,028 days. Maxaquin is licensed to Searle and is now comarketed by Searle and Wyeth-Ayerst ("The Pink Sheet" June 1, In Brief). The original Maxaquin patent was granted in 1985. With the extension, the product also would be protected until 2005. The Syntex product Ticlid (ticlopidine) had the longest review period of all ten drugs -- 15 years. Most of this time, however, was during the testing phase, and Syntex is asking for only two years extension.
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