A line-up of top US firms have taken lead roles on the $3.9bn (£2.5bn) private equity takeover of contract drug researcher Pharmaceutical Product Development (PPD), reports The Am Law Daily.

The US-based organisation is being acquired by the Carlyle Group and Hellman & Friedman after fielding offers from rival bidders including Blackstone Group and KKR.

Latham & Watkins, Simpson Thacher & Bartlett and Covington & Burling are all advising the private equity firms on the acquisition.

Latham partners Daniel Lennon and David Brown led a corporate team representing Carlyle and Hellman & Friedman. The US fim has a long history with Carlyle – Jeffrey Ferguson, the private equity house's managing director and general counsel, is a former Latham associate.

Simpson Thacher, meanwhile, is acting as counsel to Hellman & Friedman on the deal, with M&A partner Chad Skinner leading the firm's team.

Covington did not immediately identify its lawyers on the deal.

Skadden is advising PPD on the transaction, alongside Raleigh firm Wyrick Robbins Yates & Ponton.

Skadden's team includes M&A partner Ann Beth Stebbins, corporate and securities litigation partner Edward Welch, and international antitrust partner Frederic Depoortere.

PPD – which performs research for clients in the pharma, biotech, and medical device industries, as well as for academic and government organisations – has offices in 44 countries and employs more than 11,000 people worldwide.

The Am Law Daily is a US affiliate title of Legal Week.