Patents Zantac

A third basic option available in the case of some therapeutic categories is to develop an over-the-counter version of a product subject to patent expiration. The strategy has been employed for example for anti-inflammatory pain relievers such as Motrin and Naprosyn, anti-ulcer therapies such as the H2 blockers Tagamet and Zantac, proton pump inhibitors such as Prilosec, and in several other therapeutic categories. However, a shift to OTC status requires approval by the FDA that the drug is safe for self-medication (Juhl 2000 McCarran 1991 Schweitzer 1997). A company will normally need to submit new clinical trial evidence to that effect. If approved by the FDA, the company receives a three-year exclusivity period for its OTC product in recognition for the new clinical trial work. 

Because of the incredible success of Zantac, generic manufacturers were eager to enter the market with a generic version of ranitidine. Since the patent on Form 1 was set to expire in 1995, a generic manufacturer could conceivably enter the market with a Form 1 formulation without waiting for expiration of the Form 2 patent in 2002. Around... 

Figure 1 Antiulcerant market share, 1979-1997. The market share (expressed as percent of total prescriptions dispensed) of the antiulcerant market is shown over the period from 1979 to 1997. Only four products (Tagamet, Zantac, Pepcid, and Prilosec) are shown. Other products in this market not shown here are Carafate, Axid , Cytotec, Propulsid , Prevacid , and generic cimetidine and ranitidine. Note that the initial increase in market share for Zantac (1983-1986) came exclusively at the expense of Tagamet and that further erosion of Tagamet market share occurred as additional products were introduced into the market. Patent expiration for Tagamet was in 1994 when it held 10% of the market. Source From the National Prescription Audit, IMS America.

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