Merck & Co's first-quarter earnings have been boosted by good performances from diabetes drugs Januvia and Janumet, the cholesterol drug Zetia and the cervical cancer vaccine Gardasil.

Net income came in at $1.74 billion, up 67%, while turnover reached $11.73 billion, a rise of 1.3%. Merck’s best-selling treatment was once again the asthma/allergic rhinitis drug Singulair (montelukast), which inched up 1% to $1.34 billion, ahead of going off-patent in the USA in August.

The most eye-catching performance came from Januvia (sitagliptin) which generated $919 million, up 24%, while Janumet (sitagliptin plus metformin) brought in $392 million, a leap of 29%. Turnover from the HIV drug Isentress (raltegravir) reached $337 million, up 15%, while sales of Gardasil increased 33% to $284 million.

Sales of the cholesterol drugs Vytorin (ezetimibe plus simvastatin) and Zetia (ezetimibe) reached $444 million and $614 million, down 8% and up 6% respectively. Revenues from the antihypertensives Cozaar (losartan) and Hyzaar (losartan plus hydrochlorothiazide) fell 21% to $336 million, due to generic competition.

The anti-inflammatory Remicade (infliximab), the Johnson & Johnson drug which Merck sells outside the USA, contributed $519 million, down 31%, as a result of the change in marketing rights agreed with J&J for the drug and its follow-up Simponi (golimumab). Merck's new hepatitis C treatment Victrelis (boceprevir) had sales of $111 million.

Chief executive Kenneth Frazier (pictured) said the firm's performance was driven by the solid contributions across our pharmaceutical, animal health (up 8% to $821 million) and consumer care ($554 million; +7%) divisions and by our ongoing efforts to operate more effectively and efficiently". He added that "the growth momentum of our underlying business and strength of our late-stage pipeline position us well, as we prepare for the Singulair patent expiry and beyond".

No Zetia, Vytorin generics from Mylan until April 2017

Meantime, Merck has won a legal battle with Mylan after a court in New Jersey ruled that the patent on Zetia and Vytorin was "valid and enforceable". The court issued an injunction barring the approval of generic versions by Mylan until the patent on ezetimibe expires in April 2017.

Merck filed a lawsuit against Mylan in December 2009 regarding its application to the US Food and Drug Administration seeking approval to market its generic version of Vytorin prior to the patent's expiry. A separate suit regarding Zetia was made in June 2010.

A settlement was reached in May 2010 allowing India's Glenmark and partner Par Pharmaceuticals to sell a generic version of Zetia from December 2016.