Mageean started this week and replaces Dr Cathy Gibson, who left the Shire Health Group operation after less than nine months in the job.
Mageean left Avenue HKM, of which he was a founding director, in January and has spent the intervening period freelancing for Avenue and the NHS.
Prior to Avenue, Mageean was an executive director of agency forerunner Bullet Communications.
He also formerly held sales and marketing roles at Bristol Myers Squibb and spent eight years as a pharmacist at NHS London teaching hospitals.
4D clients include Novartis and Lilly UK. The agency lost its four-year hold on a European contract for Japanese pharma giant Takeda earlier this year (PRWeek, 6 August). 4D will continue to work for Takeda until the end of the year when CPR The Remedy is to take over the account.
Oxford-based 4D was set up eight years ago and has around 25 staff.
Mageean reports to Shire CEO Gloria Gibbons and Susan Byrne, president of Shire sister WPP firm Healthworld Medical Education Europe.