(Sharecast News) - GlaxoSmithKline reported full-year sales of more than £30bn on Wednesday, but warned that earnings in the current year would be hurt by generic competition to its blockbuster asthma treatment.The UK's biggest drugs company said that 2018 group sales were £30.8bn, a 2% increase on the previous year, while pre-tax profits were ahead 36% at £4.8bn.Fourth-quarter sales came in at £8.2bn and adjusted earnings per share at 31.2p. Analysts had been looking for adjusted EPS of around 27.7p.Chief executive Emma Walmsley said: "GSK delivered improved operating performances in 2018, with group sales growth, strong commercial execution of new product launches, especially [shingles vaccine] Shingrix, continued cost discipline and better cash generation."It was also a significant year for the group strategically, with the launch of a new research and development strategy focused on immunology, genetics and new technologies, together with a series of transactions that support our strategy and reshape of the group's portfolio."GSK is selling its consumer healthcare nutrition business - which includes brands such as Horlicks - to consumer goods group Unilever and is creating a joint venture with US drugs firm Pfizer. It is also buying Tesaro, a US oncology biopharma company, and looking to strengthen its pharmaceuticals pipeline. GSK said it had doubled the amount of oncology assets in clinical development to 16 since July.However, GSK said that the portfolio overhaul, along with stiffer generic competition, meant adjusted earnings per share in 2019 were now expected to decline in the range of 5% to 9%.It noted: "This guidance reflects the recent approval of a substitutable generic competition to Advair in the US, and the expected impact of the Tesaro acquisition, and assumes that the proposed consumer healthcare nutrition disposal closes by the end of 2019, and the proposed consumer healthcare joint venture with Pfizer closes during the second half."As at 12.30pm GMT, shares in GSK - which published its results at noon - were ahead 1% at 1,533p.