The notice letter went on to say that Sandoz intends to market a generic version of Remodulin before the expiration of three of United Therapeutics patents, which expire in October 2014, October 2017, and March 2029. Sandoz claims that the patents are not valid, not enforceable and/or will not be infringed by the commercial manufacture, use or sale of the proposed product described in Sandoz's ANDA submission.

Remodulin sales totalled US$403.6 million in 2010, up 21.7% on 2009, according to Zacks.

In its press release, United Therapeutics states that the company intends to vigorously enforce its intellectual property rights relating to Remodulin, including the three patents mentioned above which are listed in FDA's Approved Drug Products List, the ‘Orange Book’.

The company says that it is currently reviewing the notice letter, noting that it would take 45 days from receipt of the letter to commence a patent infringement law suit against Sandoz. Any law suit would automatically preclude FDA from approving Sandoz’s ANDA for up to 30 months or until the issuance of a district court decision that is adverse to United Therapeutics, whichever occurs first.

It is not all bad news for United Therapeutics though it recently received approval in the EU for the IV use of its pulmonary arterial hypertension treatment, which is expected to increase sales of Remodulin. The company is also looking to launch Remodulin in new territories including China and Japan. The Japanese market, where approval is expected by late 2013, could bring in incremental sales of about US$100 million.

The problem is, should Sandoz receive approval for its generic injectable, just how long will it wait before the self-proclaimed generic injectables leader goes after the intravenous version?

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