Sales, profits and earnings slumped during the last quarter of the year at drugmaker GlaxoSmithKline due to headwinds in the US market, though the company pleased investors after confirming it would return £4bn cash from its deal with Novartis.Revenues for the full year fell 3% to £23bn, due to "challenging" trading conditions in the US primary care market that saw fourth quarter sales slip 8% to £6.2bn.Vaccine sales were hit by supply constraints and tough comparatives figures from the year before, with a 10% decline in pharmaceutical and vaccines sales in the US, while emerging market sales retreated in tougher markets and generic competition weighed on its drug portfolio.Fourth quarter profits plummeted to £531m from £2.55bn as investments in new launch capacity and future manufacturing technology continued to drag, pulling full-year profits before tax significantly lower to £2.97bn from £6.65bn last year.As a result, earnings per share for the full year fell to 56.7p from 110.5p. The company posted a dividend of 80p, a rise of 3%, and said it expected to maintain it at the same level in 2015.This will be on top of the £4bn of net proceeds from its deal with Swiss competitor Novartis, which was making "good process" towards closure this year.GSK will buy Novartis' vaccines business, while Novartis will purchase GSK's cancer drugs and the two groups will merge in consumer healthcare.In another positive note, the HIV division reported a 15% increase in sales thanks to its ViiV healthcare unit, which GSK said it was "evaluating options for a potential initial public offering of a minority stake".Chief executive Andrew Witty said: "Some of the headwinds faced by the group in 2014 will continue to adversely affect performance during 2015 with a greater impact in the first half of the year."However, with annualisation of these factors and successful execution of our priorities, we expect a stronger performance in the second half of the year."Witty added a special thanks to those involved on its experimental Ebola vaccine and those who helped to progress with regulatory filing of its vaccine to prevent malaria.Analyst Keith Bowman at Hargreaves Lansdown said: "Despite reassuring management outlook comments, Glaxo has still yet to deliver. Sales and earnings continue to retreat, with falling sales of price pressured respiratory products still a major factor."He added that 2015 was viewed as a critical year for management."The completion of its three-part transaction with Novartis is awaited, a convincing sales turnaround has yet to be achieved, whilst a decision on a potential IPO of a minority stake of its HIV related ViiV Healthcare business has now to be made. On balance and weighing still challenging sales against expected cost savings, shareholder returns and hoped for new drugs, analyst consensus opinion continues to point to a hold."Shares were up 3.51% to 1,504p on Wednesday at 12:54.