TRENTON, N.J. -- Schering-Plough Corp. today reported a 48 percent plunge in first-quarter net income, due to increased spending on research, higher overhead and costs related to an acquisition -- its biggest ever -- in the prior quarter.

The maker of hepatitis and cholesterol medicines and Nasonex for allergies posted net income of $253 million, or 15 cents per share, down from $543 million, or 36 cents per share in the year-ago quarter.

Excluding acquisition costs and other one-time items, the company said it would have reported earnings of $862 million, or 53 cents per share. Those items included $688 million in accounting adjustments and another $23 million in charges related to its November acquisition of biotech company Organon BioSciences.

Analysts surveyed by Thomson Financial had expected earnings per share of 37 cents excluding one-time items, or 16 cents less than the company posted. The analysts anticipated revenues of $4.5 billion.

Shares rose 6 percent, or $1.02 cents, to $18.16 in early trading today.

Revenues reached $4.66 billion, up 56 percent from $2.98 billion in the first three months of 2007. They included $1.3 billion from sales of Organon BioSciences products.

Schering-Plough said its revenues totaled $5.3 billion, including its share of the $1.2 billion in revenues from its joint venture with Merck & Co. selling cholesterol drugs Vytorin and Zetia, revenues totaled $5.3 billion.

Sales in the pharmaceuticals division amounted to $3.6 billion, led by arthritis and inflammatory disease treatment Remicade, which saw sales jump 36 percent to $507 million.

Animal health products sales totaled $723 million, while sales of consumer products were $377 million.