Separately, in a different kind of Hatch-Waxman issue, Wyeth discontinued its original formulation for Zosyn in November 2005 and subsequently launched a new patented formulation, delaying generic entry in the US market. According to FDA rules, a company is allowed to withdraw a product from the market only for reasons related to safety and efficacy. In case the product is withdrawn from the market, it is subsequently removed from the approved drugs’ reference list, and therefore no pharmaceutical company can market a generic version of this same drug.
Three generic manufacturers (Sandoz, Abraxis and Orchid) filed citizen petitions with the FDA against Wyeth, after Wyeth received the U.S. Patent No. 6,900,184 (the ‘184 patent) on its blockbuster drug Zosyn.