Cleary Gottlieb Steen & Hamilton has advised GlaxoSmithKline (GSK) on a $3.6bn (£2.5bn) buyout as the pharma giant completes its second major deal in a week.

The firm acted for regular client GSK on its acquisition of dermatology specialist Stiefel Laboratories in a deal announced today (20 April).

Cleary's New York-based team was led by corporate partner Benet O'Reilly, alongside tax partner Sheldon Alster, employee benefits partner Arthur Kohn, real estate partner Kimberly Brown Blacklow and Washington DC-based antitrust partner David Gelfand.

Brussels-based partner Francisco-Enrique Gonzalez Diaz advised on antitrust issues. The team also included environmental and intellectual property lawyers.

Stiefel was advised by Willkie Farr & Gallagher corporate partner Greg Astrachan, the former managing partner of the firm's London office.

GSK has instructed Cleary on many occasions in the past, including last October when the firm's London-based US capital markets partner Sebastian Sperber advised on its $210m (£145m) acquisition of some of Bristol Myers Squibb's Egyptian assets.

On that deal, Cleary advised alongside Slaughter and May, a regular adviser to the company in the UK. Slaughters also advised GSK on its joint venture with pharma rival Pfizer, announced last week, to create a new HIV treatment company. M&A partners David Johnson and Simon Nicholls led for Slaughters.

Eversheds last year landed a role as sole European adviser to Stiefel, led by Cambridge commercial partner Simon Crossley.