Charles River and WuXi PharmaTech have announced a definitive agreement under which the companies will merge in a cash and stock transaction valued at $1.6bn.

The merged entity will retain the name Charles River and will offer fully integrated research and drug development services from molecule creation to first-in-human testing.

Following the transaction, Charles River will be able to expand its presence in China and utilise WuXi’s expertise in chemistry services, while WuXi will be able to accelerate its good laboratory practice toxicology capabilities.

The transaction is expected to complete by the fourth quarter of 2010, subject to customary closing conditions.