Updated from 1:42 p.m. EDT

Shares of Cardiac Science ( DFIB) were easily among the best-performing health care and pharmaceutical stocks Friday after the medical device company received marketing approval from the Food and Drug Administration for its Powerheart G3-Automatic heart defibrillator product.

The defibrillator is specifically designed for use by consumers, analyzing a patient's condition, and, if necessary, delivering a defibrillating shock to restore the heart to normal rhythm. Cardiac Science believes the annual worldwide market for automated external defibrillators will grow four to five times by the end of the decade from $200 million in 2003. Shares of Cardiac Science traded up 59 cents, or 24%, to $3.05.

Matrixx Initiatives' ( MTXX) shares fell after the company warned it expects second-quarter losses to widen from a year ago. It now expects to report a loss of 8 cents to 12 cents a share vs. a year-ago loss of 6 cents a share. It also said that it expects second-quarter sales to be flat to up 10% vs. last year's second quarter. The company's cold products were unfavorably impacted by what it called a "sudden and dramatic end of the cold season" in the first quarter. Shares of Matrixx Initiatives traded down 72 cents, or 7.3%, to $9.11.

Shares of Caremark Rx ( CMX) fell after pharmacy benefit manager said that 19 states are investigating its business practices. Caremark said that it believes its practices comply with applicable laws and regulations and intends to fully cooperate with all requests for information. Shares of Caremark traded down $1.20, or 3.7%, to $31.

Guidant ( GDT) fell after the company warned that one of its stent programs would be delayed because of a design flaw. In May, the company notified investors that a limited number of stents from its Champion stent system failed to meet its internal performance and quality standards. Over the past several weeks the company has identified changes in material and design that improves the stainless steel platform that addresses performance and quality issues. As a result, the company plans to refine the manufacturing process and improve the platform, which will lead to a six- to eight-month delay. Shares of Guidant traded down 47 cents, or 0.9%, to $55.03.

Health care volume movers included Boston Scientific ( BSX), down 3 cents to $42.67; Pfizer ( PFE), up 1 cent to $33.94; Cardinal Health ( CAH), down $1.10 to $51.76; Amgen ( AMGN), up 44 cents to $55.20; Johnson & Johnson ( JNJ), down 12 cents to $55.35; Schering-Plough ( SGP), down 1 cent to $18.07; and Genentech ( DNA), down 25 cents to $55.35.

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