Shares of SFBC International ( SFCC) were among the worst-performing health-related stocks Friday, slumping 16% after the drug-development services firm withdrew its 2006 guidance and delayed the release of its fourth-quarter earnings. The company, which was scheduled to release earnings after the bell on Thursday, said it will now issue its earnings report after the market closes on March 8. "We are diligently working with our national valuation firm to complete the assessment of a substantial non-cash impairment charge that we expect to record in the fourth quarter of 2005, related to the significant decline in business at our Miami operations," the company said. Shares of the company have been in freefall, dropping nearly 60%, since Bloomberg published a story on Nov. 2, raising ethical questions about SFBC's policy of warning test subjects of risks in medical studies. SFBC said it plans to discuss the impairment charge and update its 2006 guidance next week after it posts its results. Shares recently were trading down $3.64 to $18.65. Adeza ( ADZA) tumbled 12% after the maker of women's health products posted lower-than-anticipated fourth-quarter results and issued a weak 2006 sales guidance. The company earned $6.9 million, or 38 cents a share, on sales of $11.9 million. Excluding a one-time tax benefit, the company would have earned $2.1 million, or 11 cents a share. Analysts polled by Thomson First Call expected earnings of 12 cents a share and sales of $12 million. During the year-earlier period, the company earned $1.6 million, or 11 cents a share, on sales of $9.2 million. Looking ahead, Adeza forecast 2006 sales of $54 million to $57 million. Analysts project sales of $58.1 million. Shares were trading down $2.68 to $19.02. Shares of UnitedHealth Group ( UNH) fell modestly after the health insurer issued some $3 billion in debt. "We are pleased with investor receptivity to this offering," the company said. "The tranches issued today further expand our investor base and allow us to continue to improve our overall match of liability durations with the assets of our businesses." The company issued a variety of debt, ranging from three-year floating-rate notes to 30-year fixed-rate notes. Shares recently traded at $57.39, down 19 cents.