Shire said that the lawsuit results from an abbreviated new drug application (ANDA) filed by Actavis for generic versions of 1mg, 2mg, 3mg and 4mg guanfacine hydrochloride extended release tablets, Intuniv, which seeks to market such generic products before the expiration of the ’290, ’599, and ’794 patents. The regulatory exclusivity period for Intuniv runs through September 2, 2012.
Intuniv, a once-daily formulation of guanfacine, is the first selective alpha-2A adrenergic receptor agonist approved for the treatment of ADHD. Although the mechanism of action is unknown, Intuniv is thought to directly engage receptors found in the prefrontal cortex, an area of the brain that has been linked in preclinical research to ADHD.
Stimulation of the postsynaptic alpha-2A receptors is thought to strengthen working memory, reduce susceptibility to distraction, improve attention regulation, improve behavioral inhibition, and enhance impulse control.