Warburg Pincus L.L.C. has agreed to purchase the clinical trial outsourcing firm ReSearch Pharmaceutical Services Inc. for $227.3 million in an all-cash transaction.

Founded in 1998, Fort Washington-based ReSearch had 2009 revenues of $200.5 million; it has 2,500 employees.

The company had filed a registration statement for an initial-public offering.

Warburg Pincus is a private-equity firm.    - Bob Fernandez