Updated from 2:09 p.m. EDT

Shares of

Merck

(MRK) - Get Report

were among the worst-performing health and pharmaceutical stocks Thursday, falling 26.8% after the company pulled its Vioxx arthritis drug off the market, citing heart risk.

The company said it based its decision on new, three-year data that showed there "was an increased relative risk for confirmed cardiovascular events, such as heart attack or stroke, beginning after 18 months of treatment in the patients taking Vioxx compared to those taking a placebo." Worldwide sales of Vioxx totaled $2.5 billion in 2003. The Vioxx recall is expected to cut 50 cents to 60 cents a share in earnings. Previously, the company expected full-year earnings of $3.11 to $3.17 a share. Shares traded down $12.07 to $33.

Closure Medical

(CLSR)

fell 28% after the company cut its full-year earnings and sales forecast. The maker of bandages now expects earnings of 59 cents to 62 cents a share on sales of $40 million to $41 million. Previously, the company forecast earnings of 65 cents to 70 cents a share on sales of $45 million to $47 million. Analysts polled by Thomson First Call had expected earnings of 67 cents a share on sales of $45.8 million.

For the third quarter, Closure expects earnings of 13 cents to 14 cents a share, in line with expectations, on sales of $9.2 million, which is less than published estimates of $10.1 million. The company said the earnings and sales revision was due to its marketing partner reducing inventory levels as a result of lower-than-expected end-unit demand. Shares traded down $5.54 to $14.24.

Shares of

Urologix

(ULGX)

fell 31.5% after the company said that it would post in-line, first-quarter earnings on sales that would fall below its previous guidance. The medical-device maker expects first-quarter earnings of 4 cents to 6 cents a share on sales of $6 million. Previously, the company said it would post sales of $6.8 million to $7.2 million. Analysts are expecting earnings of 4 cents a share on sales of $7 million. The company did not offer an explanation for the sales shortfall. Shares traded down $2.91 to $6.32.

Weider Nutrition International

(WNI)

rose 17.3% after it posted first-quarter financial results that beat expectations. The nutritional supplements company posted a profit of 14 cents a share on sales of $68.9 million. A lone analyst was expecting earnings of 6 cents a share on sales of $57.6 million. A year ago the company posted earnings of 8 cents a share on sales of $63.6 million. Shares traded up 67 cents to $4.55.

Shares of

Cantel Medical

(CMN)

rose 7.9% after the company posted fourth-quarter earnings and sales that beat expectations. The health care company earned 31 cents a share on sales of $45.2 million. The lone estimate called for the company to earn 27 cents a share on sales of $42.7 million. Shares traded up $1.76 to $24.

Other health care volume movers included

Pfizer

(PFE) - Get Report

, up 42 cents to $30.60;

Schering-Plough

(SGP)

, up 56 cents to $19.06;

Nastech Pharmaceutical

(NSTK)

, up $1.89 to $14.29;

Amgen

(AMGN) - Get Report

, down $1.18 to $56.81; and

Johnson & Johnson

(JNJ) - Get Report

, down 70 cents to $56.33.