Shares of

Columbia Laboratories

(CBRX)

sank Friday despite the company's announcement that it completed the treatment phase of a late-stage study.

The phase III trial involved Prochieve, a drug intended to prevent preterm births. Phase III is the stage of trials conducted just before a drug is reviewed by the Food and Drug Administration for marketing approval. The stock fell 5.4% to $5.24.

Bentley Pharmaceuticals

( BNT) announced that its marketing partner

Perrigo

received regulatory approval for a generic version of

Merck's

(MRK) - Get Report

blockbuster cholesterol drug Zocor. Bentley also said the FDA approved the manufacturing facility where the generic drug, known as simvastatin, will be produced. Shares gained 11.7% to $10.89.

Arena Pharmaceuticals

(ARNA) - Get Report

was up 5.1% to $13.54 on an upgrade by A.G. Edwards analyst Aaron Reamer. Since reaching a recent high of $17.69, "the stock's valuation has come back into a range which we feel undervalues the market opportunity" offered by a company with three drugs in human trials, five more in early trials, and partnerships with health care giant

Johnson & Johnson

(JNJ) - Get Report

, the analyst wrote in a research report Friday. He upgraded the stock to buy from hold with a price target of $18.

Among other health stocks rising were

Novo Nordisk

(NVO) - Get Report

, 1.8% higher to $84.36;

Par Pharmaceutical

( PRX), up 2% to $21.66;

Immunomedics

(IMMU) - Get Report

, gaining 11.4% to $3.91;

Hi Tech Pharmacal

(HITK)

, up 1% to $12.18;

Repros Therapeutics

(RPRX)

, rising 15% to $8.88; and

Ariad Pharmaceuticals

(ARIA)

, up 3.6% to $4.88.

Losers included

Bayer

( BAY), falling 1.5% to $52.81;

Keryx Biopharmaceuticals

(KERX) - Get Report

, off 1.3% to $13.68;

Catalyst Pharmaceutical Partners

(CPRX) - Get Report

, down 2.1% to $4.75; and

Minrad International

( BUF), falling 2.8% to $5.15.