A good week for Shire has ended on another high note with the news that US regulators have granted marketing approval to Vyvanse, the company’s new treatment for attention deficit hyperactivity disorder.

The US Food and Drug Administration’s green-light for Vyvanse (lisdexamfetamine dimesylate) was expected and Shire said that it plans to launch Vyvanse in the second quarter in three once-daily dosage strengths of 30mg, 50mg and 70mg.

Chief executive Matthew Emmens said the firm was pleased to note that the label it received with the approval letter includes information about the extended duration of effect and abuse-related characteristics of Vyvanse “which illustrate benefits that differentiate this compound from other ADHD medicines.”

He added that Vyvanse, the follow-up treatment to Adderall XR (mixed amphetamine salts), the firm's earnings driver which becomes genericised in 2009, is now “our top promotional priority within our ADHD portfolio."

Shire believes Vyvanse can be a $1 billion-a-year drug and the company will soon have full control of the treatment once its proposed $2.6 billion acquisition of US partner New River Pharmaceuticals is completed. The market is certainly there, given some 7.8% (or 4.4 million) children in the USA aged 4 to 17 have been diagnosed with ADHD at some point in their lives, according to the US Centers for Disease Control and Prevention.

Shire’s claim that Vyvanase is less open to abuse than existing treatments can only boost its prospects, especially in the wake of the FDA’s review into the safety profile of ADHD treatments which has seen the agency request that a black box warning be added to the label of a number of drugs.