Shares in Shire rose by as much as 7 per cent on Tuesday, after the drugmaker announced a doubling of the size of its US sales force, following a deal with pharmaceutical giant Glaxosmithkline, that will increase the marketing of hyperactivity drugs to adults.

The agreement will add 600 US sales representatives from GSK, who in addition to selling Glaxo drugs will co-promote Shire’s Vyvanse drug, adding to the 600 of Shire’s own employees that are already marketing the drug.