Shire has filed lawsuits in the USA against Amneal Pharmaceuticals and Novartis' Sandoz unit for infringement of certain patents covering its attention-deficit hyperactivity disorder drug Vyvanse.

Legal action has been initiated in New Jersey following Abbreviated New Drug Applications filed across the Atlantic by Amneal and Sandoz. The generics firms are seeking approval from the US Food and Drug Administration to market copycat versions of all currently approved doses of Vyvanse (lisdexamfetamine dimesylate).

Shire noted that under the Hatch-Waxman Act, the FDA must refrain from approving the ANDAs for 30 months (ie near the end of August 2014), or until a district court decides whether the patents are invalid or not infringed.

In May, Sandoz submitted its ANDA for generic Vyvanse and Shire said at the time that it relates to all 16 patents listed in the FDA's Orange Book, which are not due to expire until 2023. In March last year, a US court upheld an FDA decision in 2007 to grant Shire five-year new chemical entity market exclusivity for the drug, following Icelandic firm Actavis' attempt to overturn it.