Shire has amassed a 560-person sales force in advance of its Monday launch of new attention deficit hyperactivity drug Vyvanse.

Shire CEO Matthew Emmens said he is hopeful the drug will be able to capture 50% market share by early next decade.

“I have challenged my marketing and sales people,” Emmens said in an interview with Reuters. “It’s not a target. But it’s an aspiration.”

Emmens added that he is “very confident” Shire will be able to switch patients to the new drug from its top-selling Adderall XR, which at 30% is the current market leader among ADHD drugs. Adderall XR took in sales of $864 million in 2006 but faces patent expiration in 2009. Shire is banking on Vyvanse to take Adderall XR’s place.

Shire is expected to sell Vyvanse at $3.40 a day, around the same price as Adderall XR.
Emmens declined to forecast how quickly a switch might occur, but said analysts were expecting a similar pattern to the switch patients made to once-daily Adderall XR from its predecessor, Adderall, when 70% of patients converted in the first 18 months.

“In some ways the market is more favorable now than it was then,” Emmens told Reuters noting that Adderall XR had only four months to become established before generic Adderall was launched. Adderall XR also faced competition from rival treatment, Johnson & Johnson’s Concerta. Vyvanse however is poised to get a boost in sales this fall when Concerta loses patent protection.
 
Vyvanse’s selling point is that the drug is less open to abuse because it cannot be metabolized until it reaches the stomach.

Shire developed Vyvanse with New River Pharmaceuticals. Shire acquired New River in February in a deal worth $2.6 billion.