Shares of

Panacos Pharmaceuticals

(PANC)

were among the best-performing health-related stocks Monday, rising 49% after the company reported positive results for its experimental drug that fights HIV.

The drug, known as PA-457, met its primary endpoint of demonstrating a statistically significant reduction in the level of HIV in the blood compared to a placebo. At its highest dose, the drug showed a median reduction in viral load of 90%. "We are extremely pleased with the results of this important phase IIa study," the company said. "We believe that PA-457 is a potential breakthrough drug that could play a role throughout the HIV treatment spectrum." The company now plans to initiate a phase IIb study of the drug, which will be conducted during the first half of 2006. Shares were trading up $3.48 to $10.53.

Eyetech Pharmaceuticals

( EYET) rose 30% after the company agreed to be acquired by

OSI Pharmaceuticals

( OSIP) for about $935 million in cash and stock. Based on Friday's closing prices, the deal values Eyetech at $20 a share, representing a premium of 43%. OSI will pay for 75%, or $15 a share, of the deal in cash. The transaction is expected to close by the end of 2005. "OSI is the ideal partner for Eyetech. With OSI, we create a powerful new biopharmaceutical franchise, one with scale, depth of resources as well as strength and security of a diversified and growing base," Eyetech said in a statement. Shares of Eyetech were recently trading up $4.14 to $18.13 while shares of OSI were trading down $8.61, or 21%, to $32.16.

Shares of

Biolase Technology

( BLTIE) fell 5% after the medical technology company announced the discontinuation of its dividend. The company believes shareholders will be better served by eliminating the dividend, which had been paid every other month. "These funds will be redirected toward research and development initiatives and general corporate purposes," it said. Shares were trading down 27 cents to $5.45.

Penwest Pharmaceuticals

( PPCO) rose 25% after

Endo Pharmaceuticals

(ENDP) - Get Report

posted positive results from its phase III clinical trial of oxymorphone extended-release tablets. The study, which was conducted in response to the Food and Drug Administration's request for additional clinical data that would support Endo's new drug application, showed a statistically significant difference in pain scores between oxymorphone ER and a placebo during a 12-week treatment period. In October 2003 the FDA issued an approvable letter for oxymorphone ER, but requested that Endo conduct an additional clinical trial that would confirm the safety and efficacy of the product. Penwest's proprietary time-release technology is used in Endo's oxymorphone product. At the time, the FDA also requested that Endo address some of the agency's questions and provide additional clarification and information regarding oxymorphone. Endo expects to submit a complete response to the FDA's approvable letter some time during early 2006. Shares of Penwest were recently trading up $2.81 to $14, while shares of Endo Pharmaceuticals were trading up $1.09, or 4%, to $28.45.

Shares of

Alpharma

(ALO) - Get Report

rose 24% after the company said that it is continuing to seek various strategic alternatives aimed at maximizing shareholder value. "To date, the company has not entered into, and its board of directors has not approved, any material definitive agreements regarding strategic alternatives, and the company's policy is to not comment on potential transactions," the company said. Shares were trading up $4.90 to $24.91.

Other health care volume movers included

Merck

(MRK) - Get Report

, down 65 cents to $27.41;

Pfizer

(PFE) - Get Report

, down 12 cents to $25.43;

Bristol-Myers Squibb

(BMY) - Get Report

, down 10 cents to $24.58;

Johnson & Johnson

(JNJ) - Get Report

, unchanged at $63.57;

Schering-Plough

( SGP), up 8 cents to $20.97; and

Amgen

(AMGN) - Get Report

, down 36 cents to $79.30.