Updated from 2:50 p.m. EDT

Shares of

Pozen

(POZN)

were among the best-performing health-related stocks Thursday, rising 67.9% after the company said Trexima, its migraine drug, met all of its endpoints in a second phase III trial.

The drug, which is being codeveloped with

GlaxoSmithKline

(GSK) - Get Report

, demonstrated a superior and sustained pain-free response compared with other pain relievers such as naproxen and sumatriptan. As for pain relief and the associated symptoms of nausea, photophobia and phonophobia, the drug performed better than a placebo at two hours. Pozen believes that no additional preclinical or clinical trials will be necessary for submission of the drug to the Food and Drug Administration. The company expects to submit a new drug application for Trexima during the third quarter of 2005. Shares traded up $2.41 to $5.96.

Enzon Pharmaceuticals

(ENZN)

fell 14.8% after the biotech company lowered its 2005 sales guidance and announced the resignation of its chief financial officer. Enzon now expects North American sales of Abelcet to be around $45 million to $50 million, down from previous guidance of $55 million to $60 million. As a result of the weaker outlook for Abelcet, the company now expects combined sales for its four internally marketed products of between $90 million to $105 million, down from previous guidance of $100 million to $115 million. Separately, the company said that Kenneth Zuerblis resigned, effective April 21. The company, which will begin an immediate search for a new CFO, said Zuerblis left for personal reasons. Shares were trading down $1.40 to $7.55.

Shares of

Matria Healthcare

(MATR) - Get Report

fell 10.6% after the company posted mixed first-quarter results and warned that second-quarter earnings and sales would fall below expectations. Excluding discontinued operations, the company earned $4 million, or 22 cents a share, on sales of $77.6 million. Analysts were expecting earnings of 21 cents a share on sales of $78.7 million. Looking ahead, Matria forecast second-quarter earnings of 23 cents to 25 cents a share on sales of $80 million to $82 million. Analysts had been expecting earnings of 26 cents a share on sales of $82.6 million. Shares traded down $3.28 to $27.75.

Omnicell

(OMCL) - Get Report

fell 11.5% after the company, which provides a broad array of health care solutions, previewed first-quarter results that were below expectations. When the company posts full results on April 26 it expects to post a pro forma loss of 10 cents to 12 cents a share on sales of $28.2 million to $28.8 million. Analysts had been expecting a profit of 3 cents a share on sales of $29.7 million. The company called the first quarter "challenging" and said that it has positioned itself to break even during the second quarter. Analysts are expecting second-quarter earnings of 5 cents a share on sales of $31 million. Shares traded down 85 cents to $6.54.

Shares of

Transkaryotic Therapies

(TKTX)

rose 15.7% after the company agreed to be acquired by

Shire Pharmaceuticals

( SHPGY) for about $1.6 billion, or $37 a share in cash. The price represents a 22% premium over Wednesday's closing price of $30.44. The deal, which still requires regulatory and shareholder approval, is expected to close during the third quarter of 2005. Shares traded up $4.77 to $35.21.

Other health care volume movers included

Pfizer

(PFE) - Get Report

, up 49 cents to $27.25;

Schering-Plough

( SGP), up 75 cents to $20.70;

Amgen

(AMGN) - Get Report

, up $1.12 to $59.25;

Merck

(MRK) - Get Report

, up 21 cents to $34.28;

Johnson & Johnson

(JNJ) - Get Report

, up 19 cents to $68.29;

Elan

(ELN)

, up 11 cents to $3.94; and

Genentech

( DNA), up 31 cents to $71.