Shire PLC and GlaxoSmithKline PLC signed a three-year deal to co-promote Shire's Vyvanse drug to U.S. doctors.

Shire, which has North American headquarters in Wayne, has built a big franchise in treatments for attention deficit hyperactivity disorder.

Having GlaxoSmithKline, the world's second-biggest drug company, as a partner could help boost the sales of Vyvanse, which were nearly $320 million last year.

GlaxoSmithKline is based in London but employs about 5,000 people in the Philadelphia region.

Shire needs to replace revenue it expects to lose when its billion-dollar drug, Adderall XR, goes off-patent in April and faces cheaper generic competition.