He joins OMG after an entrepreneurial stint as co-founder of Results and Outcomes.
Mediacom had previously held the pharma company's media account since 2016.
The agency will be tasked with media strategy, planning and buying duties.
Eileen Ooi was previously chief operating officer.
Omnicom names Guy Marks as EMEA media chief as Mike Cooper becomes Europe vice-chairman.
Bharat Khatri was previously country head for India with Xaxis.
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