Updated from 1:53 p.m. EDT

Shares of

Thoratec

(THOR) - Get Report

were among the worst-performing health care and pharmaceutical stocks Wednesday after the company warned that its second-quarter and full-year earnings results would fall short of expectations.

Citing weaker-than-expected sales of its Destination Therapy implants, Thoratec said it expects to earn 2 cents a share on sales of $40 million to $41 million during the second quarter. Analysts polled by Thomson First Call had been expecting the company to earn 7 cents a share on sales of $44 million. For the full year, it expects to earn 10 cents to 13 cents a share on sales of $175 million to $180 million. Analysts were expecting earnings of 31 cents a share on sales of $186.6 million. Shares of Thoratec traded down $3.68, or 25.5%, to $10.74.

Trinity Biotech

(TRIB) - Get Report

rose after it received a waiver for its Uni-Gold Recombigen HIV test from the Food and Drug Administration. The waiver clears the way for the company to market its HIV test to almost 200,000 test sites in the U.S., including doctor's offices and clinics. The FDA had originally approved Trinity's HIV test on December 23, 2003. Shares of Trinity Biotech traded up 35 cents, or 11.6%, to $3.37.

Shares of

Cima Labs

(CIMA)

rose after the Federal Trade Commission allowed the proposed merger between Cima and

Cephalon

( CEPH) to go forward. The two companies will now work toward quickly closing the deal. Originally, Cephalon agreed to buy Cima for about $34 a share back in November, but the FTC requested additional information earlier this year, which slowed the transaction. Shares of Cima Labs traded up $1, or 3.1%, to $33.73.

Forest Laboratories

(FRX)

fell after the company said it received a request from the New York State Attorney General Eliot Spitzer for any

information that may exist with respect to off-label clinical trials or promotion of its products. The attorney general is concerned that Forest may be in violation of New York state law. Forest intends to fully cooperate with the attorney general and believes it is in compliance with all New York laws. Shares of Forest Laboratories traded down $1.02, or 1.8%, to $56.63.

Shares of

Alnylam Pharmaceuticals

(ALNY) - Get Report

rose after the company announced it would collaborate with

Merck

(MRK) - Get Report

as part of a multiyear agreement to develop therapies for age-related macular degeneration and other ocular diseases.

Alnylam will receive an initial cash payment and can potentially earn as much as $19.5 million in milestone payments over the life of the agreement. What's more, the two companies will jointly fund the development of any RNAi therapeutics and share in the profits of any products sold in the United States. Merck will conduct marketing and sales outside of the U.S., with royalties going to Alnylam. Shares of Alnylam Pharmaceuticals traded up 46 cents, or 6.5%, to $7.56.

Health care volume movers included

Pfizer

(PFE) - Get Report

, down 6 cents to $34.28;

Amgen

(AMGN) - Get Report

, up 48 cents to $54.57;

Johnson & Johnson

(JNJ) - Get Report

, down 4 cents to $55.70;

Genentech

( DNA), up $2.13 to $56.20; and

Schering-Plough

( SGP), up 21 cents to $18.48.