Shares of Thoratec ( THOR) were among the worst-performing health-related stocks Wednesday, tumbling 21% after the maker of heart disease products issued a 2006 forecast that fell below Wall Street expectations.

The company's fourth-quarter results topped forecasts. Thoratec earned $4.5 million, or 8 cents a share, on sales of $54.8 million. Excluding items, the company earned $8.9 million, or 16 cents a share. Analysts polled by Thomson First Call expected earnings of 11 cents a share, before items, on sales of $53 million. A year earlier, Thoratec posted adjusted earnings of $6 million, or 12 cents a share, on sales of $48.3 million.

For 2006, Thoratec sees earnings of $22 million to $24 million, or 40 cents to 44 cents a share, before items. Analysts project earnings of 48 cents a share. The company forecast sales of $217 million to $225 million, short of Wall Street's target of $227.2 million. Shares were trading down $5.30 to $20.

GeoPharma ( GORX) jumped 12% after the pharmaceutical company said it swung to a third-quarter profit and reported an 80% increase in sales. The company earned $365,000, or 3 cents a share, on sales of $12.4 million, for the quarter ended Dec. 31. During the year-ago quarter, the company posted a loss of $960,000, or 12 cents a share, on sales of $6.9 million. Shares were up 56 cents to $5.31.

Candela ( CLZR) soared 30% after the medical laser maker posted better-than-expected fiscal second-quarter results. Candela's income for the December period rose to $4.5 million, or 19 cents a share, from $1.7 million, or 7 cents a share, a year earlier. Analysts polled by Thomson First Call were expecting earnings of 12 cents a share. The company's second-quarter revenue jumped 34% to $37.7 million, beating analysts' target of $33.4 million. Candela shares were up $4.38 to $19.35.

Shares of Angiotech Pharmaceuticals ( ANPI) climbed 11% after the company said it plans to buy privately held American Medical Instruments for $785 million in cash. The acquisition of American Medical, which had 2005 sales of about $174 million, will immediately add to Angiotech's 2006 and 2007 earnings, the company said. The deal is expected to close during the second quarter. Shares of Angiotech Pharmaceuticals were trading up $1.40 to $13.98.

Molina Healthcare ( MOH) vaulted 13% after the company previewed better-than-expected fourth-quarter earnings. The company projects earnings of 35 cents to 39 cents a share, well above the 21 cents a share that analysts had forecast.

Looking ahead, Molina sees 2006 earnings of about $1.37 to $1.47 a share, including stock-based compensation expenses of 8 cents a share, on premium revenue of about $1.9 billion. Analysts project earnings of $1.41 a share, excluding stock-based compensation costs, on revenue of $1.79 billion. Molina shares were up $3.52 to $29.98.

Shares of Nastech Pharmceutical ( NSTK) jumped 20% after the company signed a co-development agreement with Procter & Gamble's ( PG) pharmaceutical division. The deal could be worth as much as $577 million over the life of the agreement. Nastech will grant P&G the rights to develop and commercialize its PTH1-34 nasal spray. P&G, meanwhile, will pay Nastech an upfront payment of $10 million and could pay an additional milestone payment of $22 million during the first year of the deal. Nastech also will receive double-digit royalties that are tied to product sales. Shares of Nastech were up $3.18 to $19.08.

Other health care volume movers included Amgen ( AMGN), up $3.51 to $76.50; Pfizer ( PFE), up 21 cents to $25.89; Teva Pharmaceutical Industries ( TEVA), up 17 cents to $42.80; Genta ( GNTA), up 11 cents to $2.73; Elan ( ELN), down 28 cents to $15.63; Bristol-Myers Squibb ( BMY), up 39 cents to $23.18; Johnson & Johnson ( JNJ), up 31 cents to $57.85; Boston Scientific ( BSX), down 7 cents to $21.80; Merck ( MRK), down 18 cents to $34.32; and Gilead Sciences ( GILD), up 29 cents to $61.16.