DRUGS giant GlaxoSmithKline has agreed to buy a US skin specialist for up to £2.5bn.

GSK is to acquire Stiefel Laboratories to create a dermatology business with combined revenues of about £1.03bn – an 8% share of the global prescription dermatology market.

The new operation will retain the Stiefel brand within GSK and will continue to be headed by Charles Stiefel, the group’s current chairman and chief executive.

The deal comes just days after GSK announced it was spinning off its HIV treatment division in a tie-up with US rival Pfizer.

GSK estimated both businesses could save a combined £164.8m a year by 2012, although integration costs are set to total about £223m over the next three years.

Stiefel lays claim to being the largest independent dermatology company in the world, with six manufacturing plants, a global research and development network and 30 owned subsidiaries.

The group produces treatments for a range of skin ailments, such as Duac for acne and Olux E for dermatitis.

It also has more than 15 new products in late-stage development.

Stiefel made sales of about £618m last year, while GSK’s dermatology business achieved sales of £377.8m.

Andrew Witty, chief executive of GSK, said: “This transaction will create a new world-leading, specialist dermatology business and re-energise our existing dermatology products.

“The addition of Stiefel’s broad portfolio will provide immediate new revenue flows to GSK with significant opportunities to enhance growth through leveraging our existing global commercial infrastructure and manufacturing capability.”

Glaxo one of the big hitters of the FTSE 100, employs about 100,000 people worldwide, including about 18,000 in the UK, where it has a number of manufacturing sites.