Generic competition for the allergy medicine Claritin resulted in sharp declines in practically every measure of Schering-Plough's ( SGP) first-quarter financial performance.

The drug company said it earned $173 million, or 12 cents a share, on sales of $2.1 billion in the period, down from earnings of $600 million, or 41 cents a share, on sales of $2.6 billion last year. The result in the latest quarter was 2 cents better than the 10 cents a share the company guided analysts to in March.

The company's newly appointed chief executive, Fred Hassan, said he was withdrawing the company's full-year guidance, which had been for earnings of 75 cents to 85 cents a share.

"Having just arrived, I am assessing this situation and believe it is right not to be constrained by the business assumptions that supported the previously stated earnings guidance," he was quoted saying.

The advent of generic Claritin led to a 26% decline in worldwide pharmaceuticals sales at Schering-Plough to $1.6 billion, including a 52% tumble in the U.S. to $648 million. Favorable currency exchange helped boost international pharmaceuticals sales 13% to $980 million.

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