Updated from 2:13 p.m. ESTShares of Aceto ( ACET) were among the worst-performing health-related stocks Friday, falling 19.3% after the company warned that second-quarter earnings would fall short of expectations. The pharmaceuticals distributor now expects earnings of 10 cents a share, which is below the 12 cents to 15 cents a share that it had previously forecast. Analysts polled by Thomson First Call had been expecting earnings of 14 cents a share. The shortfall, according to the company, is due to competitive pricing on certain chemical-based pharmaceutical ingredients, tight production demand in China, costs associated with the company's new business initiatives and an unexpected bad debt expense. Full results will be issued on Feb. 3. Shares traded down $2.27 to $9.49. Beckman Coulter ( BEC) fell 6.7% after the maker of medical-testing devices posted fourth-quarter earnings that were lower than expected. The company earned $59.8 million, or 91 cents a share, on sales of $693 million. Analysts were expecting earnings of 98 cents a share on sales of $685.9 million. A year ago the company posted earnings of $59 million, or 90 cents a share, on sales of $638.6 million. Looking ahead, Beckman forecast first-quarter earnings of 59 cents to 66 cents a share on sales growth of 6% to 9%. Analysts are expecting earnings of 64 cents a share on sales of $573.6 million, or sales growth of about 6.9%. Shares traded down $4.78 to $66.40. Shares of Idexx Laboratories ( IDXX) fell 2% Friday after the maker of diagnostic products posted solid fourth-quarter results but warned that first-quarter earnings would fall below expectations. The company earned $16.9 million, or 49 cents a share, on sales of $144.3 million. Analysts were expecting earnings of 48 cents a share on sales of $134.5 million. Looking ahead, Idexx forecast first-quarter earnings of 50 cents to 51 cents a share on sales of $152 million to $154 million. The forecast excludes an acquisition-related charge of 3 cents a share. Analysts had been expecting earnings of 53 cents a share on sales of about $145 million. Shares traded down $1.15 to $55.93.