Drugmaker GlaxoSmithKline sank to a fourth-quarter loss of 546 million pounds ($758 million) from a profit of 257 million pounds a year earlier, as it dealt with U.S. tax changes.

The deterioration came despite a 1 percent rise in sales to 7.6 billion pounds.

CEO Emma Walmsley said Wednesday that the company is bracing for competition in the coming year in its core respiratory and HIV businesses. The company says it can see a potential for a generic version of its blockbuster asthma drug Advair.

Nonetheless, she says the company is committed to delivering on three new drugs in its pipeline: Trelegy Ellipta, an inhaler for COPD; Juluca, an HIV treatment, and Shingrix, a vaccine for the prevention of shingles.