Updated from 2:22 p.m. EDT

Shares of

Mylan Labs

(MYL) - Get Report

were among the best-performing health and pharmaceutical stocks Thursday after the company said that Carl Icahn received clearance to buy its stock.

The Federal Trade Commission granted an early termination to the antitrust waiting period, which clears the way for Icahn to make a sizeable investment in the company. Icahn had requested that he be allowed to buy between $100 million and $500 million of Mylan's stock. Mylan has not had any conversations with Icahn and does not know what purchases, if any, Icahn will make. Without submitting another filing, Icahn would be allowed to purchase 2.4% to 11.9% of Mylan's outstanding stock based on Tuesday's closing price. Shares of Mylan Labs traded up $1.62, or 10.4%, to $17.20.

Amedisys

(AMED) - Get Report

fell after the company said it would sell up to 2 million shares of stock. The home nursing provider also granted the underwriters an option to buy an additional 300,000 shares, of which up to 150,000 shares may be offered by selling shareholders. Amedisys intends to use the proceeds for general corporate purposes. Shares traded down $2.23, or 7.5%, to $27.55.

Shares of

Weider Nutrition

( WNI) fell after the company delivered weaker-than-expected-fourth-quarter earnings results. The nutritional supplements company posted a fourth-quarter profit of 5 cents a share on sales of $65.6 million. An analyst surveyed by Thomson First Call was expecting earnings of 7 cents a share on sales of $60.4 million. A year ago, Weider earned 1 cent a share on sales of $55.8 million. Shares traded down 45 cents, or 11.4%, to $3.50.

Amsurg

(AMSG)

fell after it was downgraded by Stephens to equal weight from overweight. In lowering its price target to $24 from $29, Stephens said concerns about high physician turnover during the second quarter, along with the resignation of its senior vice president of operations on Tuesday, led to the downgrade. Shares of the surgical center operator traded down $1.51, or 6.8%, to $20.57.

Shares of

Medtronic

(MDT) - Get Report

traded down after the company posted first-quarter earnings that were in-line on weaker-than-expected sales. During the first quarter the medical-device maker posted a profit of 43 cents a share on sales of $2.346 billion, which was just below expectations of $2.35 billion. Looking ahead, Medtronic backed analysts' estimates of 45 cents a share in earnings on sales of $2.5 billion for the first quarter. Shares of Medtronic traded down 11 cents, or 0.2%, to $49.48.

Other health care volume movers included

Pfizer

(PFE) - Get Report

, down 37 cents to $31.48;

King Pharmaceuticals

( KG), down 3 cents to $12.09;

Amgen

(AMGN) - Get Report

, up 13 cents to $57.39;

Boston Scientific

(BSX) - Get Report

, up $1.10 to $35; and

Schering-Plough

( SGP), down 15 cents to $18.23.