Irish firm UDG Healthcare has agreed to pay up to £84m (€94m) to buy UK group STEM Marketing.
UDG's activities include sales, marketing and medical communications outsourcing, and pharmaceutical packaging.
UDG Healthcare chief executive Brendan McAtamney said STEM is an "excellent strategic fit" for the group. He said STEM has an established global footprint and strong growth opportunities. It will complement UDG's existing Ashfield division.
UDG, part of the FTSE-250, is paying an initial £55m for STEM, which includes £50m in cash and £5m in UDG shares. An additional consideration of up to £29m, which would include £24m in cash and £5m in UDG shares, is payable over the next three years contingent on certain financial targets being achieved.
STEM has about 30 clients and delivers projects in 35 countries around the world. Its customers include 18 of the world's top 20 pharma firms.
STEM's 2015 accounts show that it generated turnover of £18.2m that year, up from £13.5m the year before. It made a pre-tax profit of £5.5m in 2015. It generated £3.28m in cash last year. Of its 2015 turnover, £12.8m was generated between the UK, mainland Europe, Canada and Australia. The US accounted for £3m.