FOSTER CITY, Calif. (AP) — SciClone Pharmaceuticals said net income slid 25 percent in the second quarter as expenses increased and sales of its vaccine booster Zadaxin fell.

The company reported results after the market closed Monday, and shares tumbled nearly 9 percent as SciClone stuck to its outlook for the year, which is more modest than most Wall Street predictions.

The company said it earned $5.5 million, or 11 cents per share, compared with $7.3 million, or 16 cents per share in the year-ago quarter. Revenue fell 6 percent, to $20.7 million from $22 million.

All of the company’s revenue comes from sales of Zadaxin. Sales last year soared due to the swine flu outbreak in China, where SciClone markets its product heavily.

The company said research and development costs fell to $2.4 million from $3.6 million because it did not spend as much on clinical trials. But sales and marketing costs rose to $5.6 million from $4.8 million due to Zadaxin promotions in China. General and administrative costs rose to $3.4 million from $2.7 million.

SciClone backed its annual profit and revenue forecasts of 31 to 35 cents per share on $82 million to $85 million in revenue. Analysts expect 36 cents per share and revenue of $82.5 million.

SciClone Pharmaceuticals Inc. is based in Foster City, Calif.