Shire Pharmaceuticals yesterday reiterated that it would not be suing Teva Pharmaceuticals even though the latter company has launched a second challenge to the former’s top selling ADHD medication, Adderall XR (amphetamine salts extended-release) [[09/06/05e]].

Earlier this year, Shire said it would not be filing a suit against Teva, which had challenged the patent covering the 10mg and 30mg doses of the drug [[23/02/05b]], [[12/04/05d]]. Teva has since filed for US approval of the 5mg, 15mg and 20mg doses of the drug [[09/06/05e]].

Shire reiterated that its US patents covering the drug, which generated 2004 sales of $607 million – up 28%, [[03/03/05d]], are not set to expire until 2018. However, this has not stopped several generics manufactures filing their copycat offerings for approval in the all-important US market. First off the starting blocks was Barr Laboratories [[10/01/03b]], followed by Impax Laboratories [[05/01/04d]], and Colony Pharmaceuticals [[03/12/04d]]. Shire has filed lawsuits against both Barr and Impax and is expecting these cases to go to trial in January and February 2006 respectively. As with Teva, Shire has chosen not to sure Colony.

The UK company is keen to point out that neither Barr, Impax, Colony nor Teva may not launch a generic version of Adderall XR before receiving a final approval from the US Food and Drug Administration. Should Barr receive a tentative approval from the FDA, it cannot lawfully launch its drug before the earlier of the expiration of the currently pending 30-month stays or a district court decision in its favour. Impax, Colony and Teva, which cannot launch their offerings without FDA approval, also have to wait for the expiration of the 180 days of marketing exclusivity that Barr is claiming as a result of being the first to file for the generic green light.

- Meanwhile, Shire says that the judge presiding over the company’s patent infringement lawsuit against Nostrum Pharmaceuticals for the anti-epileptic, Carbatrol (carbamazepine extended release), has denied Nostrum’s motion for summary judgment [[14/01/04b]].

Consequently, the lawsuit between Shire and Nostrum will continue to move toward trial, although no date has yet been set. The court’s ruling also maintains the 30-month stay of approval of Nostrum’s drug under the Hatch-Waxman Act, which is not set to expire until February next year. A generic version of the drug cannot be launched before the expiration of this stay or a favourable court ruling, in addition to receiving regulatory approval.