Shares of

Dov Pharmaceutical

( DOVP) were among the worst-performing health-related stocks Tuesday, plunging 41% after the company said its medication for chronic low back pain didn't achieve a statistically significant effect compared with a placebo.

Dov said that bicifadine didn't show a significant difference at any of the doses tested in its first phase III trial. "We are disappointed by the unexpected results of our phase III trial, study 020," the company said. Dov said it plans to continue phase II trials of the drug in osteoarthritis and neuropathic pain, along with two other phase III trials of bicifadine in chronic low back pain. "We will provide more detailed guidance regarding our bicifadine chronic pain program once we are in a position to do so," Dov said. Shares were trading down $6.05 to $8.64.

Shares of

Serologicals

( SERO) jumped 33% after the biological products company agreed to be acquired by

Millipore

(MIL)

in a deal valued at $1.4 billion. Serologicals shareholders will receive $31.55 a share, representing a 35% premium to Monday's closing price of $23.32. The deal, which also includes the assumption of debt, is expected to close by June 30.

On the basis of 2006 projections, Millipore expects the combined company to post annual revenue of $1.4 billion. Millipore expects 2007 sales growth of 9% to 11%. Assuming the transaction closes on time, Millipore expects Serologicals to add 10 cents to 15 cents a share to 2006 earnings, resulting in pro forma earnings of $3 to $3.10 a share. "The strategic combination of Millipore and Serologicals will significantly strengthen Millipore's bioscience division by giving it leading positions in high-growth segments such as drug discovery products and services, antibodies, cell biology reagents and stem cell research," Millipore said in a statement. Shares of Serologicals were trading up $7.79 to $31.11, while shares of Millipore rose $5.30 to $74.65.

Shares of

NutriSystem

(NTRI) - Get Report

soared 32% after the provider of weight-management and fitness products posted first-quarter results that flew by Wall Street expectations. The company earned $22.3 million, or 60 cents a share, on revenue of $146.8 million. Analysts polled by Thomson First Call expected earnings of 41 cents a share and revenue of $125.1 million. During the year-earlier quarter, the company earned $3.2 million, or 10 cents a share, on revenue of $37.4 million. "NutriSystem continues to be in high growth mode and we continue to show improvement against our most important metrics, including customer and revenue growth, free cash flow generation and declining customer acquisition costs," the company said.

For the second quarter, NutriSystem sees earnings of 44 cents to 46 cents a share, with revenue of $118 million to $122 million. Analysts project earnings of 35 cents a share and revenue of $105 million. Shares were up $16.22 to $66.92.

Shares of

LCA-Vision

(LCAV)

rose 7% after the laser vision-correction services company posted better-than-anticipated first-quarter results and raised its full-year forecast. The company earned $13.1 million, or 61 cents a share, on revenue of $73.4 million. Analysts expected earnings of 50 cents a share and revenue of $67.5 million. A year ago, the company earned $9.3 million, or 44 cents a share, on revenue of $50.2 million.

Looking ahead, LCA-Vision predicts 2006 earnings of $1.75 to $1.85 a share, up from an earlier view of $1.65 to $1.75 a share. The company said it continues to expect revenue growth of at least 30% to 40% for the balance of 2006. Analysts project full-year earnings of $1.74 a share and revenue of $252.1 million. Shares were up $3.56 to $54.76.

Despite posting better-than-expected earnings,

Alcon

( ACL) tumbled 11% Tuesday, as investors focused on the eye-care company's slight first-quarter revenue miss. Alcon's earnings rose to $295.7 million, or 95 cents a share, from $249.5 million, or 80 cents a share, a year earlier. Revenue rose to $1.16 billion from $1.1 billion. Analysts expected earnings of 90 cents a share on revenue of $1.17 billion.

Alcon forecast 2006 earnings of $4.03 to $4.12 a share on revenue of $4.8 billion to $4.85 billion. Analysts project earnings of $4.09 a share on revenue of $4.8 billion. Shares were trading down $11.86 to $98.89.

Other health care volume movers included

Pfizer

(PFE) - Get Report

, up 4 cents to $24.83;

Boston Scientific

(BSX) - Get Report

, down 2 cents to $22.06;

Discovery Labs

(DSCO)

, down $2.36 to $2.33;

Sepracor

( SEPR), down $2.90 to $45.07;

UnitedHealth Group

(UNH) - Get Report

, down 86 cents to $49.30;

Amgen

(AMGN) - Get Report

, down 37 cents to $66.37;

Johnson & Johnson

(JNJ) - Get Report

, down 12 cents to $58.21;

Medtronic

(MDT) - Get Report

, down 76 cents to $49.03;

Merck

(MRK) - Get Report

, down 20 cents to $34.17;

Bristol-Myers Squibb

(BMY) - Get Report

, up 28 cents to $24.87;

Schering-Plough

( SGP), down 2 cents to $19.30.