Merck & Co's fourth-quarter sales have been boosted by good performances from diabetes drugs Januvia and Janumet and the cervical cancer vaccine Gardasil, but the US giant is expecting a tough 2012.

Net income came in at $1.51 billion, up from a loss of $531 million in the like, year-earlier period. The latter included a $1.7-billion charge related to vorapaxar, its much-touted blood clot drug which has suffered clinical setbacks.

Turnover reached $12.29 billion, up 2%, but that includes 5% from foreign exchange. Merck’s best-selling treatment was once again the asthma/allergic rhinitis drug Singulair (montelukast), up 8% to $1.46 billion, although those figures will fall later this year as the treatment goes off-patent in the USA in August.

The most eye-catching performances came from newer products; Januvia (sitagliptin) which generated $960 million, up 42%, while Janumet (sitagliptin plus metformin) brought in $386 million, a leap of 34%. Turnover from the HIV drug Isentress (raltegravir) reached $387 million, up 24%, while sales of Gardasil ails ncreased 24% to $274 million.

Sales of the cholesterol drugs Vytorin (ezetimibe plus simvastatin) and Zetia (ezetimibe) reached $475 million and $640 million, down 16% and up 2% respectively. Revenues from the antihypertensives Cozaar (losartan) and Hyzaar (losartan plus hydrochlorothiazide) increased 3% to $427 million.

The anti-inflammatory Remicade (infliximab), the Johnson & Johnson drug which Merck sells outside the USA, contributed $511 million, down 28%, as a result of the change in marketing rights agreed with J&J for the drug and its follow-up Simponi (golimumab). The anti-allergy medication Nasonex/Asmanex (mometasone) brought in $325 million, a rise of 7%, while sales of the brain cancer drug Temodar (temozolomide) reached $230 million (-13%), hit by generic competition in Europe.

Merck's new hepatitis C drug Victrelis (boceprevir) had sales of $87 million. This is in stark contrast to Vertex's rival Incivek (telaprevir), which itself was launched in May, like Victrelis, which had fourth-quarter sales of$456.8 million.

Chief executive Kenneth Frazier (pictured) said that "we closed out 2011 with a high-quality fourth-quarter by growing the top and bottom lines. Our overall performance for the year confirms our ability to achieve strong operating results while investing for the longer term".

However for 2012, Merck expects revenue "to be at or near 2011 levels" on a constant currency basis, but at current exchange rates, sales would be unfavourably affected by about 2%-3%. Earnings are forecast to be in the range of $3.75-$3.85 per share, down from $3.77 in 2011.