Shares of Prana Biotechnology ( PRAN) were among the worst-performing health-related stocks Monday, falling 60.4% after the company halted its Alzheimer drug study.

The company said that it would not proceed with a phase II study because it found unacceptably high levels of a toxic form of PBT1, or clioquinol, during the manufacturing process of PBT1. The company said that attempts to reduce the impurity to safe levels would not likely be successful so it decided to halt further development of the drug. Prana is now conducting a strategic review of its development programs, it said. Shares traded down $1.98 to $1.30.

Northfield Laboratories ( NFLD) rose 31.6% after the company said that an independent safety committee recommended that its phase III trial to study PolyHeme move ahead without modification or a change in the study's sample size. Northfield said this is the first time that a hemoglobin-based oxygen-carrying resuscitative fluid has passed the patient evaluation point in a phase III trial studying the high-risk trauma population. The company is evaluating the safety and efficacy of PolyHeme in patients who suffer from hemorrhagic shock following traumatic injury. The primary endpoint of the study is survival at 30 days. Shares traded up $3.78 to $15.75.

Shares of Cell Therapeutics ( CTIC) rose 6.6% after the company said that its phase II trial studying patients with late-stage, relapsed or refractory multiple myeloma showed promising results. The data showed that 22 of 37 patients, or 60%, achieved an objective response. Of the 29 patients who had previously failed to respond to thalidomide or lenolinamide therapy, 14 of them responded to the company's Trisenox combination regimen of melphalan, Trisenox and vitamin C. The company said that the regimen was well tolerated and that only a few adverse events, which included mild cyopenias, fluid retention and neuropathy, occurred. The company said that it would continue to enroll more patients as it moves toward its goal of enrolling 60 patients for the study. Shares traded up 24 cents to $3.87.

Orthofix International ( OFIX), an orthopedic device maker, rose 6.4% after the company lifted its first-quarter sales target. The company now expects sales of $77 million to $78 million, up from an earlier projection of $73 million to $75 million. Analysts polled by Thomson First Call had been expecting sales of $75 million. Orthofix said that a significant sales increase in spinal stimulation products led to the upward revision. The company plans to post first-quarter earnings on April 28. Shares traded up $2.50 to $41.74.

Other health care movers included Pfizer ( PFE), down 14 cents to $26.46; Sepracor ( SEPR), down 76 cents to $57.05; Elan ( ELN), down 2 cents to $3.72; Millennium Pharmaceuticals ( MLNM), up 6 cents to $8.22; Amgen ( AMGN), up 65 cents to $59.33; Schering-Plough ( SGP), up 19 cents to $19.52; Johnson & Johnson ( JNJ), up 25 cents to $68.89; and Merck ( MRK), down 19 cents to $33.14.