A few health stocks peeked through dreary indices on Monday, while

Encysive

( ENCY) fell hard on word from the Food and Drug Administration.

Encysive tumbled $1.80, or 44%, to $2.30, after announcing the

FDA's refusal to approve Thelin, its pulmonary arterial hypertension treatment.

Encysive wasn't the only one cast in a downward direction.

Keryx Biopharmaceuticals

(KERX) - Get Report

took a less-pronounced hit. The New York-based company's CFO, Ronald Renaud, is resigning effective June 27. Renaud said he has decided to pursue an opportunity closer to his home in Boston. Chief Accounting Officer Mark Stier will take over for all financial functions. Shares were down 71 cents, or 6.3%, to $10.77.

As an aside, Keryx also said Monday that it has finished the randomization of the last patient in a late-stage trial for diabetic neuropathy drug Sulonex. It expects to have the last patient to complete the six-month trial by the end of the year.

Renaud is taking over the CFO position at

Idenix,

(IDIX)

in Cambridge, Mass., at month's end. Shares of Idenix were down 34 cents, or 5.2%, to 6.5%.

Geron

(GERN) - Get Report

was also down at the week's start. The biopharmaceutical company increased its stake in TA Therapeutics, a joint venture with Hong Kong-based Biotechnology Research Corp. to 75% from 50%. Its shares lagged 17 cents, or 2.14%, to $7.70

On the other hand,

Labopharm

( DDSS) picked up the pace, rising 33 cents, or 12%, to $3.23. The Canada-based specialty pharmaceutical company reported that the FDA's Canadian counterpart gave marketing and sale approval for its once-daily pain treatment tramadol.

Labopharm said it's in active discussions to finish a licensing and distribution agreement for the product and expects to launch it later this year. Tramadol is currently available in a multidose-per-day version in several countries.

Other winners were

Vical

(VICL)

and

Lexicon Pharmaceuticals

(LXRX) - Get Report

.

Vical climbed 89 cents, or 18%, after announcing that its Japanese licensee found

positive interim results for a late-stage trial involving its DNA delivery technology in an angiogenesis product.

Lexicon Pharmaceuticals entered an agreement in which investment firm Invus Group will take ownership of 16.4 million shares of Lexicon common stock for $3.09 each. On top of that, Invus is purchasing 20.4 million shares for $4.50 apiece, making it a 40% owner in Lexicon when all of its shares are accounted for.

Woodlands, Tex.-based Lexicon also announced a $60 million collaboration with Symphony Capital Partners, in which $15 million is allocated for Lexicon's general corporate purposes and $45 million will go to Symphony Icon, a new company created to accelerate Lexicon's first three products and hold the license to their intellectual property.

For $60 million in funding, Symphony Icon investors are receiving 7.7 million Lexicon shares for $3.13 each. As part of this agreement, Lexicon has the option to acquire 100% of the equity of Symphony Icon at exercise prices from $72 million in the second year to $90 million in the fourth year, according to the company. Lexicon was up 17 cents, or 5.5%, to $3.25.

The upward moves in Labopharm and Lexicon weren't quite enough to balance out stocks including Encysive, Keryx and Geron in the Nasdaq Biotechnology Index, which was down 6.73, or 0.8%, to 826.14.