Updated from 2:41 p.m. EDT

Shares of

Avanir Pharmaceuticals

(AVN)

were among the worst-performing health-related stocks Monday, falling 10.5% after the company posted a wider second-quarter loss and announced the resignation of its chief executive.

The company posted a loss of $14.1 million, or 14 cents a share, on sales of $645,000. Results included a $7.2 million charge related to the company's acquisition of additional rights to Neurodex. Analysts polled by Thomson First Call were expecting a loss of 8 cents a share. A year ago, the company reported a loss of $6.7 million, or 9 cents a share, on sales of $856,000.

Separately, Avanir announced that Gerald Yakatan resigned as CEO, effective immediately. After his resignation, Yakatan will serve as a consultant for one year, advising the company on its Neurodex new drug application. Charles Mathews, the company's chairman, will assist management on day-to-day operational matters until a permanent CEO is found. Shares traded down 29 cents to $2.48.

PetMed Express

(PETS) - Get Report

rose 11.1% after the pet pharmacy company posted fourth-quarter earnings that were better than expected. The company earned $2.4 million, or 10 cents a share, on sales of $23.5 million. Analysts were expecting earnings of 7 cents a share on sales of $23.8 million. A year ago, the company earned $1.3 million, or 6 cents a share, on sales of $21.5 million. Shares traded up 72 cents to $7.22.

Shares of

Dialysis Corp. of America

( DCAI) rose 0.5% after the company posted a 23% increase in first-quarter sales on a double-digit increase in earnings. The company, which manages freestanding kidney hemodialysis centers, earned $324,000, or 4 cents a share, on sales of $10.6 million. A year ago, the company earned $288,000, or 3 cents a share, on sales of $8.6 million. Shares traded up 9 cents to $17.60.

Bioenvision

( BIVN) traded actively after the company posted a third-quarter loss that was narrower than expected. The company reported a loss of $2.9 million, or 8 cents a share, on sales of $1.4 million. Analysts were expecting a loss of 12 cents a share on sales of $1.24 million. A year ago, the company posted a loss of $4.1 million, or 21 cents a share, on sales of $850,000. Shares traded down 11 cents to $6.77.

Other health-care volume movers included

Pfizer

(PFE) - Get Report

, up 37 cents to $28.23;

Onyx Pharmaceuticals

(ONXX)

, down $4.56 to $27.29;

Elan

TST Recommends

(ELN)

, down 4 cents to $7.22;

Celgene

(CELG) - Get Report

, up $1.65 to $38.65;

Amgen

(AMGN) - Get Report

, up 87 cents to $62.99;

Genentech

( DNA), up $1.07 to $73.77;

Merck

(MRK) - Get Report

, down 1 cent to $33.45;

Cell Therapeutics

(CTIC) - Get Report

, down 7 cents to $3.48;

Johnson & Johnson

(JNJ) - Get Report

, up 54 cents to $67.64;

Bristol-Myers Squibb

(BMY) - Get Report

, up 16 cents to $25.46; and

Schering-Plough

( SGP), up 10 cents to $20.35.