After an enthusiastic midweek hop, biotech stocks rounded out a blasé end-of-week performance with business updates and legal matters Friday.

Celera

( CRA), however, emerged as a winner. The company said Friday it received a $2 million milestone payment from

Merck

(MRK) - Get Report

for the advancement of odanacatib for osteoperosis into a phase III clinical trial.

Celera, an

Applera

(ABI)

subsidiary, and Merck have had a collaboration agreement since 1996 on a program targeting cathepsin K, an enzyme believed to play a role in osteoperosis. Merck has been sole responsible for research and development since February 2003.

Celera shares gained 3.7% to $14.05. Applera was unchanged. Merck was 1.2% lower at $51.65.

Other stocks dealt with the aftermath of business updates:

Idenix Pharmaceuticals

(IDIX)

lost ground after announcing a

restructuring plan to focus on hepatitis C virus (HCV) and HIV programs. The company amended an agreement with

Novartis

(NVS) - Get Report

to discontinue all activities for hepatitis B treatment Tyzeka and cutting a third of its workforce. The plan is expected to result in annual savings of $40 million to $45 million.

Idenix, a component of the Nasdaq biotechnology index, lost 17 cents, or 5.6%, to $2.86. The index was down 5.03, or 0.6%, to 854.37.

Also on the way down was

Par Pharmaceuticals

( PRX), which said it expects lower earnings as competitive pressures have resulted in scaled back sales of several products. It gave guidance of between 95 cents a share and $1.10 a share -- or between $1.05 and $1.20 a share after one-time events -- on revenue of $730 million to $765 million. The Thomson Financial consensus target was $1.56 a share.

Par also announced today that its board approved an expansion of its share-repurchase program of up to $75 million of the company's common stock. Shares rolled down $3.07, or 14%, to $18.61.

Elsewhere,

Isis Pharmaceuticals

(ISIS)

said after the market close Thursday it purchased all of the equity of Symphony GenIsis for $120 million. Earlier in the month, Isis announced that it would do so before closing

a metabolic-disease focused collaboration with

Johnson & Johnson's

(JNJ) - Get Report

Ortho-McNeil. Isis was down 2.5% at $14.97.

And some stocks moved on legal news.

Pfizer

(PFE) - Get Report

said today that the Canadian Federal Court in Toronto ruled that its second medical use patent covering Viagra would be infringed by Apotex's proposed generic product and granted the company's application for an order preventing Apotex from launching a generic version of Viagra until expiration of Canadian Patent No. 2,163,446 in 2014. The decision is subject to appeal. Nonetheless, Pfizer edged down 32 cents, or 1.4%, to $24.43.

Also,

Bristol-Myers Squibb

(BMY) - Get Report

announced Friday that it finalized a civil settlement agreement with the Department of Justice and the U.S. Attorney for the District of Massachusetts, wrapping up previously disclosed investigations beginning several years ago with regard to pricing and sales and marketing activities. The company entered a five-year corporate integrity agreement and will pay a previously announced $499 million in civil resolution. Shares were down just 19 cents, or 0.7%, to $28.82.