The most recent generics to come out of the company are generic versions of Doryx (doxycyline hyclate delayed-release) and Eli Lilly’s Cymbalta (duloxetine hydrochloride).

Doryx is a tetracycline-class antibacterial indicated for rickettsial infections, sexually transmitted infections, respiratory tract infections, specific bacterial infections, ophthalmic infections, anthrax, including inhalational anthrax (post-exposure), alternative treatment for selected infections when penicillin is contraindicated, adjunctive therapy in acute intestinal amebiasis and severe acne, and prophylaxis of malaria.

Cymbalta is a serotonin and norepinephrine reuptake inhibitor indicated for the treatment of major depressive disorder, generalised anxiety disorder, diabetic peripheral neuropathic pain and fibromyalgia.

Impax announced, on 29 December 2010, that the FDA had granted final approval of its ANDA for generic doxycyline hyclate delayed-release 75 mg and 100 mg tablets. However, alleged patent infringement litigation going back to December 2008 is still ongoing.

On 22 November 2010 the FDA granted tentative approval of Impax’s ANDA for generic duloxetine hydrochloride 20 mg, 30 mg and 60 mg capsules. This tentative approval, however, means that the generic cannot yet be marketed in the US because of existing patents and/or exclusivity rights.

US sales of Cymbalta capsules were approximately US$3.0 billion for the 12 months up to 30 September 2010, whereas Doryx sales of 75 mg and 100 mg tablets were approximately US$25 million in the 12 months up to October 2010.

Meanwhile, Impax has filed ANDAs containing paragraph IV certifications for generic versions of high cholesterol treatments from Daiichi Sankyo Welchol (Colesevelam HCl) and from Abbott Simcor (niacin/simvastatin), as well as for Alza Corporation’s attention deficit disorder drug Concerta (methylphenidate hydrochloride). Daiichi Sankyo and Genzyme Corporation filed a patent infringement suit against Impax on 19 November 2010, followed by Abbott on 24 November 2010 and Alza Corporation on 29 November, formally initiating the patent challenge process under the Hatch-Waxman Act.

Impax develops controlled-release and specialty generics in addition to the development of branded products.