Patel, previously the Hertfordshire-based body’s NHS liaison manager, takes the title head of comms.
He will run a media relations and public affairs team that also includes press manager Geraldine Clark and press officer Mark Beckett.
Viitanen held the title head of PR and public affairs before she left the organisation last autumn.
She has since launched her own health comms consultancy, PRimage Services, which is aiming to provide pharma product comms, consumer healthcare brand comms and PA counsel.
Viitanen is running the Herts-based firm alongside husband Peter, a marketing specialist who has previously worked for various investment banks.
Before joining the NPA, Patel worked for Boots the Chemist as group pharmacy manager in the Brighton area.