Merck filed a lawsuit seeking to head off a bid by Teva for a generic version of the brand manufacturer’s Nasonex allergy spray.

According to the complaint, filed July 3 in the U.S. District Court for the District of Delaware, Teva filed a Paragraph IV ANDA seeking to invalidate Nasonex’s (mometasone furoate monohydrate) ‘353 patent in late May. Merck contends that an ANDA on Nasonex before the patent’s Oct. 2017 expiration would constitute infringement.

Merck also complains that Teva has refused to provide samples of its proposed Nasonex generic.

Nasonex earned Merck $1.3 billion in 2012, the complaint says. The drugmaker has fought to maintain its market grip on the nasal spray despite setbacks, including a ruling last year that while the ‘353 patent is valid, it would not be infringed by a separate ANDA filed against it by generics maker Apotex in 2009.

The FDA’s Orange Book currently lists no generic Nasonex manufacturers. — Bryan Koenig

Originally appeared in Drug Industry Daily, the pharmaceutical industry’s number one source for regulatory news and information. Click here for more information.