Shares of

Neurocrine Biosciences

(NBIX) - Get Report

were among the worst-performing health-related stocks Friday, plunging 29% after

Pfizer

(PFE) - Get Report

pulled the plugged on its partnership with the company to develop Indiplon.

Neurocrine said it will seek approval for the insomnia drug on its own. "While we are disappointed that we will not be working with Pfizer for the commercialization of Indiplon, Neurocrine is fully committed and prepared to develop and commercialize this product," the company said in a press release. Pfizer will continue to support Indiplon for the next 180 days for a transition period, Neurocrine said. Shares of Neurocrine were trading down $4.07 to $9.74.

Penwest Pharmaceuticals

( PPCO) and

Endo Pharmaceuticals

(ENDP) - Get Report

moved sharply higher Friday after the Food and Drug Administration approved their painkiller Opana in two forms. "The FDA's final approval of Opana ER is good news for physicians and patients, and it is a key milestone for Penwest," Penwest said. "This represents a major step in advancing our strategy of building a specialty pharmaceutical company with a focus on developing compounds targeted at disorders of the nervous system." Endo said it expects to start selling the drug in the U.S. during the coming weeks. Shares of Penwest surged $6.08, or 38%, to $22.17, while shares of Endo were up $2.60, or 9%, to $31.35.

Shares of

Health Management Associates

(HMA)

fell 5% after the hospital operator cut its full-year earnings outlook for the second time in three months. The company now sees full-year earnings of $1.30 to $1.34 a share, down from an earlier view of $1.43 to $1.49 a share. Analysts polled by Thomson First Call project earnings of $1.43 a share. For the second quarter, Health Management anticipates earnings of 31 cents to 34 cents a share, below the 36 cents a share that analysts project. "Patient volumes and uncompensated care continue to be the two most significant issues for the hospital industry, including HMA," the company said. Separately, the company announced a $250 million stock buyback program. Shares were down 99 cents to $19.64.

Bradley Pharmaceuticals

( BDY) fell 6% after the company's first-quarter revenue missed Wall Street's target. The company reported a loss of $352,642, or 2 cents a share, on revenue of about $34.8 million. The results included a payment of $2.9 million, or 18 cents a share, related to a licensing agreement and stock-based compensation costs of 5 cents a share. Analysts expected earnings of 18 cents a share and revenue of $36.5 million. Last year, Bradley posted a first-quarter profit of $2.2 million, or 13 cents a share, on revenue of $33.2 million. Shares were trading down 79 cents to $12.21.

Other health care volume movers included Pfizer, up 8 cents to $22.73;

Teva Pharmaceutical Industries

(TEVA) - Get Report

, up 85 cents to $32.10;

Boston Scientific

(BSX) - Get Report

, down 23 cents to $18.38;

Merck

(MRK) - Get Report

, down 35 cents to $34.90;

Johnson & Johnson

(JNJ) - Get Report

, up 37 cents to $61.55;

Amgen

(AMGN) - Get Report

, up 53 cents to $65.50;

Millennium Pharmaceuticals

( MLNM), up 19 cents to $9.94;

Elan

(ELN)

, up 29 cents to $16.97;

UnitedHealth Group

(UNH) - Get Report

, up $1.06 to $45.49;

Bristol-Myers Squibb

(BMY) - Get Report

, down 5 cents to $25.58;

Schering-Plough

( SGP), up 1 cent to $19.18.