Acadia Pharmaceuticals' ( ACAD) shares were up more than 15% after an analyst said the recent drop in the company's stock presents an opportunity to buy.

"We believe that Acadia has an emerging pipeline with five promising clinical programs targeting large central nervous system markets such as schizophrenia and Parkinson's disease," wrote Banc of America Securities biotech analyst David Witzke in a research report. He pointed out that the stock is down about 64% since its equity offering in April. He initiated coverage of the stock with a buy rating and set a price target of $10. Shares advanced 83 cents to $6.32.

Genzyme ( GENZ) published results of a clinical trial involving its drug Tolevamer for diarrhea caused by the bacteria Clostridium difficile, sending the shares 1.3% higher to $67.37.

According to data from the trial, in which 300 patients received either Genzyme's Tolevamer or the antibiotic vancomycin, patients saw similar results, with the results indicating a possible reduction in the recurrence rate with the Genzyme drug. Vancomycin is currently the only FDA-approved drug to treat the infection.

Biopharmaceutical company Novavax ( NVAX) shares were up 13% to $3.21 after an upgrade from RBC Capital Markets. While analyst Ken Trbovich notes that the company's quarterly results were weaker than expected, "with the stock trading near $3 per share, it no longer carries the significant downside risk that lead us to rate NVAX shares underperform," Trbovich wrote. The analyst raised his rating on the stock to sector-perform.

Among other health stocks on the move were Hospira ( HSP), down 1.9% to $34.80, Tenet Healthcare ( THC), whose shares sank 3.4% to $7.29, and Novogen ( NVGN), whose stock was 2.2% lower at $10.22.

Elsewhere, Osteotech ( OSTE) gained 7.1% to $3.92, Cytokinetics ( CYTK) was up 5.9% to $5.59, CAS Medical Systems ( CASM) rose 4.8% to $6.07, New River Pharmaceuticals ( NRPH) soared 13.8% to $26.20, Rotech Healthcare ( ROHI) climbed 3.3% to $1.25, and AMN Healthcare Services ( AHS) was up 1.5% to $22.24.

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