Merck & Co’s earnings for the first quarter have taken a thumping, hit by costs relating to the acquisition of Schering-Plough and other charges, but the latter’s contribution led to a doubling of sales.

Net income came in at $298.8 million, a decline of 79%, but revenues shot up 112% to $11.42 billion. Merck’s best-selling treatment was once again the asthma/allergic rhinitis drug Singulair (montelukast), which rose 10% to $1.17 billion, though revenues from the antihypertensives, Cozaar (losartan) and Hyzaar (losartan plus hydrochlorothiazide) were down 7% to $782 million. The company now expects to suffer “a significant decline” in sales of the two drugs since they lost marketing exclusivity in the USA in April and in major European markets during the first quarter.

Combined sales of the cholesterol drugs Vytorin (ezetimibe plus simvastatin) and Zetia (ezetimibe) were up some 4% to $1.01 billion. The diabetes drug Januvia (sitagliptin) performed well, generating $511 million in the quarter, up 24%, while Janumet (sitagliptin plus metformin) brought in $201 million, a leap of 56%. Turnover from the HIV drug Isentress (raltegravir) reached $232 million, up 57%, while sales of the cervical cancer jab Gardasil fell 11% to $233 million.

As for S-P’s products, the anti-inflammatory Remicade (infliximab), the Johnson & Johnson drug which Merck sells outside the USA, contributed $674 million, up 30%, while the anti-allergy medication Nasonex/Asmanex (mometasone) brought in $320 million, an increase of 4%.

Sales of the brain cancer drug Temodar (temozolomide) reached $274 million (+11%), though the hepatitis C treatment PegIntron (pegylated interferon) fell 14% to $186 million. Fertility treatment Follistim/Puregon (follitropin beta) and the contraceptive Nuvaring had sales of $134 and $135 million, respectively, up 2% and 17%.

Chief executive Richard Clark said the first full quarter of results for the new Merck “reflect our strong focus on driving revenue growth, maintaining the momentum of the business and reducing our cost structure”. The company claims that it has been “moving rapidly to complete integration actions” and remains on track to achieve its synergy target of $3.5 billion of annual savings in 2012.

Merck noted that US healthcare reform reduced revenues by $33 million in the quarter and for the full-year the impact will be about $170 million.