US Court of Appeals Decides Enantiomer Patent Term Extension Case

We don't usually report on US issues, but Jeffrey S. Boone, Vice President, Intellectual Property, for Covidien (Hazelwood, Missouri, US) has kindly sent us this update on patent term extensions in the US.

"In the United States, the Court of Appeals for the Federal Circuit (CAFC) today (2010 May 10) issued its decision in the case of Ortho-McNeil Pharmaceutical, Inc. v Lupin Pharmaceutical, Inc. The court decided that the previous approval of a racemic mixture does not prevent a patent term extension for a single isomer of the racemic mixture.

US 4,382,892 claims ofloxacin, an antibiotic which is a racemic mixture of equal amounts of two stereoisomers (enantiomers). The patent was granted in 1983 and the US FDA approved the commercial marketing of ofloxacin (FLOXIN®) in 1990. In 1991 a subsequent patent, US 5,053,407, was granted for levofloxacin, one of the enantiomers in ofloxacin. In 1996 the FDA granted marketing approval for levofloxacin, which has been sold under the proprietary name LEVAQUIN®.

The plaintiff submitted an application for a Hatch-Waxman patent term extension for the ‘407 patent, which claims the single enantiomer. With full knowledge that the racemic mixture had been previously granted marketing approval, the FDA decided that the marketing approval of levofloxacin (the single enantiomer), was the “first” permitted commercial marketing or use of the “product”, as defined under 35 USC 156(f)(1). Thus, the FDA decision, which was consistent with several similar prior cases, was essentially that the racemic mixture and the single enantiomer were not the same “product”, as defined by the statute.

In litigation that resulted from the defendant’s filing of an ANDA (an application for a generic version of LEVAQUIN), the defendant, Lupin, argued that an enantiomer is half of its racemate, and thus the enantiomer was a component of the previously approved drug. However, the district court declared on 2009 April 30 that the patent term extension was valid.

Now, the court of appeals has affirmed the district court. The court quoted one of the witnesses who stated “in each and every instance in which it has considered the question, the FDA has described a racemate as a single active ingredient, distinct from its enantiomers, and each enantiomer as a single active ingredient distinct from the other and from the racemate”."

You can read the case here.