A PHARMACEUTICAL firm says the tumbling pound has bolstered earnings but warned it could face increased competition in the asthma sector.

GlaxoSmithKline posted a 36 per cent rise in underlying operating profits to £7.8bn for 2016 thanks to the pound’s EU referendum plunge.

However, bosses issued caution and warned of uncertainty if US regulators allow generic competitors to its asthma drug Advair.

The update came just hours after Durham County Council approved plans for GlaxoSmithKline to expand its factory in Barnard Castle, County Durham.

The business is building an aseptic facility, which will provide a base to make and supply injectable liquids for treatments of HIV and respiratory and auto-immune diseases.

The Northern Echo also previously revealed the plant could support the launch of a fresh remedy for lupus, with bosses confirming they were submitting plans for regulatory approval for a new therapy to ease symptoms such as facial rashes and extreme tiredness.

According to the company’s latest financial results, released yesterday, it enjoyed a 17 per cent rise in annual revenues to £27.8bn, with a 21 per cent leap coming in the fourth quarter.

With the benefit of the weak pound on overseas earnings stripped out, full-year revenues were six per cent higher, while operating profits lifted 14 per cent.

The group said, based on current exchange rates, the weak pound would increase turnover by around six per cent this year.

However, officials warned if generic competition to Advair is launched in the US this summer, it could wipe out earnings growth and even leave earnings per share lower.

Advair lost patent protection in 2010 though other versions have yet to receive regulatory approval.

But Sir Andrew Witty, outgoing chief executive, said the group hopes new asthma medicines will help offset the potential blow.

He said: “We face some uncertainty as to the level of our earnings performance, given the possibility of substitutable generic competition to Advair in the US.

“While there will be an inevitable financial impact to absorb, we fully expect to maintain leadership in this therapy area given our new product portfolio and the innovation we have in our pipeline.

Sir Andrew will hand over to the group’s former consumer healthcare boss, Emma Walmsley, in March.

Last year, the Echo reported how a pioneering Barnard Castle-made gel, aimed at saving children from umbilical cord deaths in poorer countries, is now being used in Kenya.

The gel, which uses an ingredient already found in a company mouthwash, is expected to be rolled out across the rest of Africa.

It was produced after Dr Pauline Williams, GlaxoSmithKline’s head of global health research and development, saw potential for the drug while reading a United Nations report at home.