Shire Plc (SHP L), the UK’s third-largest drugmaker with headquarters in Basingstoke, won US approval for use of its Vyvanse hyperactivity treatment in adult patients resulting in the largest jump in it’s stock since October 2006.

The Food and Drug Administration (FDA) approved the medicine in July 2007 for children between 6 and 12 years old with attention deficit hyperactivity disorder. More than 1 million prescriptions have been written since then, the Basingstoke-based company said today in a statement.

Shire said in February that its target of $350 million to $400 million in 2008 Vyvanse sales hinged on adult patients, a group Shire says is the fastest growing segment of the ADHD market. The drugmaker needs Vyvanse to replace sales it loses when the treatment’s predecessor, Adderall XR, loses patent protection next year.

The medicine, which brought in $76.5 million for Shire by the end of last year, has a 6.9 percent share of the market for ADHD treatments, Shire said. That’s an increase from 6.3 percent market share as of Feb. 21. The six biggest managed care plans now cover the product, Shire said.

Shire surged 6.5 percent to close at 978 pence in London trading. Before today, the shares had lost 20 percent this year.

This news comes shortly after the company announced that it is looking to quit the UK.

Via Bloomberg UK