Perrigo Licenses Antihistamine Levocetirizine, “Prime” Switch Candidate

Perrigo's licensing agreement with Synthon Pharmaceuticals to market a generic of UCB's antihistamine Xyzal brings the private labeler a "prime example" of an Rx-to-OTC switch candidate. Switch is a "likely scenario" for the allergy drug, Perrigo maintains.

However, whether the drug remains prescription or switches OTC, Perrigo stands to benefit only if Synthon's abbreviated new drug application for a generic version of the allergy drug clears FDA and the firms can weather a patent suit filed by the innovator.

Synthon, based in Research Triangle Park, N.C., licensed to Perrigo exclusive U.S. rights to sell and distribute levocetirizine tablets, according to a Sept. 8 release. Synthon says it was the first to file an ANDA for generic Xyzal, which makes the product eligible for 180-day generic exclusivity in the event of a successful patent challenge.

UCB has filed Paragraph IV/Hatch-Waxman litigation against Synthon over the ANDA filing, triggering a 30-month statutory stay on FDA action on the application.

The stay expires between July and September 2010, at which point Synthon and Perrigo could launch a generic version of the prescription drug, said Perrigo Chief Financial Officer Judy Brown.

However, UCB's patents on the drug run through 2012, and Synthon would not comment on whether it would launch a generic version at risk. UCB launched the drug in 2007 in partnership with Sanofi-Aventis.

At stake in the litigation is an estimated $200 million in sales of prescription Xyzal (levocetirizine), which is growing 15 percent per year, according to data provided to Perrigo by Wolters Kluwer.

If the product switches as expected it would mark a level of maturity in the OTC market for low- and non-sedating antihistamines, in which several other former prescription products now compete.

Among the OTC competition is Schering-Plough's Claritin (desloratadine), which switched in 2002, and sold $149.6 million in cold and sinus tablets/packets in the 52 weeks ending Aug. 10, according to Information Resources, Inc., a Chicago-based marketing research firm. IRI data does not include sales from Wal-Mart, club stores or gas/convenience stores (¹ (Also see "Schering OTC Claritin Post-Approval Filings To Include Hypospadia Reports" - Pink Sheet, 2 Dec, 2002.), p. 3).

McNeil Consumer Products' Zyrtec sold $155 million in sinus tablets/packets between its launch as an OTC product in November 2007 and Aug. 10, according to IRI (² 'The Tan Sheet' Nov. 19, 2007, In Brief).

The market also includes private label competition, which sold $556 million worth of tablets/packets in the 52 weeks ending Aug. 10 - roughly 22 percent of the total cold/allergy/sinus tablets/packets market, according to IRI data. That figure includes private label equivalents of older antihistamines.

Xyzal's Potential For Switch Is "High"

Xyzal is "a prime example of a product that would have a high likelihood of switching in the future" because it is similar in structure and indication to other OTC allergy drugs, Brown said.

For example, levocetirizine is similar in structure to Zyrtec (cetirizine hydrochloride). This similarity could make levocetirizine an easier sell to an FDA advisory committee reviewing it for a switch - especially considering the agency's approval "track record of this type of product," Brown said.

Brown said that if the product is switched, Perrigo would be ready as the "leading over-the-counter generic engine in the U.S." However, "if it does not switch, we as well have a generic prescription business that can also market the product."

Either way, private-payers could drive Xyzal business toward Perrigo and Synthon by providing better coverage of generic or OTC levocetirizine. In a growing trend, insurers are covering or promoting OTCs when they can replace prescription drugs.

Blue Cross Blue Shield of Rhode Island recently covered the full cost of generic OTC allergy medications as an alternative to more expensive prescription drugs as part of a pilot program. Other insurers provide coupons for OTCs or promote them via formulary placement (³ (Also see "WellPoint NextRx/BCBS Pilot Program Encourages Members To Buy OTC" - Pink Sheet, 14 Apr, 2008.), p. 3).

This, combined with the threat of generic prescription levocetirizine, could spur UCB to switch the drug OTC earlier.

- Elizabeth Crawford ([email protected])