Shire secures successor to Adderall XR as US FDA approves Vyvanse: another predicted blockbuster

UK drugmaker Shire says that the US Food and Drug Administration has granted marketing approval for Vyvanse (lisdexamfetamine dimesylate; formerly known as NRP104), its predicted blockbuster drug for attention-deficit hyperactivity disorder.

Shire will book all Vyvanse sales after it announced last week that it is set to acquire its US partner and the drug's orginator, New River Pharmaceuticals, in a $2.6 billion cash transaction (Marketletter February 26). The Basingstoke-based firm hopes to launch Vyvanse in the second quarter of the year and expects it to generate over $1.0 billion in annual sales. The US market for ADHD drugs is valued at $3.3 billion and is growing 4% each year.

Shire hopes that Vyvanse will provide it with a replacement for its top-selling drug Adderrall XR (mixed amphetamine salts), another ADHD agent which faces threat of generic competition once its patent expires in 2009. In a note to investors, analysts at Lehman Brothers suggest that, with full control of the product, they expect Shire to pursue an "aggressive" switching strategy, adding that, while this will reduce earnings per share in the short term, it will secure Shire's ADHD franchise in the long term and lower the chances of generic competitors after 2009.