Updated from 2:26 p.m. EDT

Shares of Vivus ( VVUS) were among the best-performing health care stocks Wednesday, after the Mountain View, Calif.-based company announced positive phase II results for its treatment for sexual arousal disorder.

The company said that 64% of Alista doses resulted in satisfying sexual events in premenopausal women. The study also showed that patients experienced an increase in the total number of satisfying sexual encounters vs. a placebo. The study involved six sites and 36 women who received at least one dose each of a placebo and active drug. Vivus's Alista drug will now move into phase III clinical testing. Shares of Vivus traded up 68 cents, or 18%, to $4.46.

Genzyme ( GENZ) rose after it reported strong second-quarter earnings and sales. Excluding items, it reported a profit of 44 cents a share on sales of $549.6 million. Analysts polled by Thomson First Call had expected it to earn 40 cents a share on sales of $497 million. The strong quarterly results were helped by sales of Genzyme's Fabrayme and Renagel drugs. Shares of Genzyme traded up $5.50, or 12.4%, to $50.

Shares of MGI Pharma ( MOGN) rose after the company reported better-than-expected second-quarter earnings and sales. Citing strong Aloxi injection sales, it earned 11 cents a share on sales of $47.9 million. Analysts had expected it to earn 5 cents a share on sales of $37 million. Separately, MGI Pharma announced that it entered into a three-year agreement with Alpharma to promote Alpharma's Kadian, a morphine drug that is used to treat pain associated with cancer. Initially, MGI Pharma and Alpharma will share profits related to the sales of Kadian. Shares of MGI Pharma traded up $2.04, or 7.8%, to $28.11.

TriPath Imaging ( TPTH) fell after it announced preliminary sales results that fell short of expectations. Though earnings are expected to be between break-even and 1 cent a share, in line with expectations, sales of nearly $17 million are lower than analysts had expected. TriPath's earnings results will be released August 5. Shares of TriPath Imaging traded down 42 cents, or 5%, to $7.99.

Shares of K-V Pharmaceutical ( KVa) fell after the company announced the resignation of its independent auditor, BDO Seidman.

It said that its financial statements for each of the past two years did not contain an adverse opinion or disclaimer from BDO Seidman. However, the company did say that subsequent to the fiscal year ended March 31 and through the date of BDO's resignation that BDO notified K-V's audit committee of a reportable condition in the internal control structure of the company.

The condition related to deficiencies in customer credit processing and the "lack of sufficient and timely management review of the company's accounts receivable reserves to identify the issue." K-V said the condition was immediately rectified once the situation was identified. Shares of K-V Pharmaceutical traded down $1.72, or 7.8%, to $20.47.

Other health care volume movers included Pfizer ( PFE), down 15 cents to $34.01; Amgen ( AMGN), up 98 cents to $55.50; Schering-Plough ( SGP), up 37 cents to $18.58; HCA Healthcare ( HCA), up 78 cents to $41.43; Johnson & Johnson ( JNJ), up 54 cents to $55.92; and Genentech ( DNA), up 46 cents to $52.70.