Amanda Moulson has been brought on board to head up a new London office - the agency's first outside the US.
Moulson will work with media director Vanessa Leon, who joins following freelance work at Edelman. Moulson said she planned to recruit more staff as the agency grows.
Moulson will work on projects with existing pharmaceutical clients and will also be looking for new clients in Europe. She reports to Chamberlain founder and principal director Richard Chamberlain.
Chamberlain, based in New York, was acquired by US pharmaceutical marketing company InVentiv Health in February last year.
InVentiv followed the acquisition with the buy-out of global healthcare specialist Chandler Chicco Agency for £32.5m later in the year (PRWeek, 27 June 2007).
Chamberlain said: 'Despite a challenging environment our business is growing.'