Abbott Labs'

(ABT) - Get Report

strong sales of antibiotics and pain relievers during the first quarter have bolstered analysts' expectations for the company's earnings report Tuesday morning.

For the first quarter, the Thomson First Call consensus estimate calls for a profit of $912.2 million, or 58 cents a share, on revenue of $5.3 billion, vs. $831.9 million, or 53 cents a share, on revenue of $4.64 billion for the same period a year ago, adjusted for the spinoff of its hospital products group,

Hospira

(HSP)

.

Some analysts see Abbott possibly beating those estimates by a penny a share because of increased U.S. sales of its antibiotics Biaxin and Omnicef during the late flu season and safety concerns about Cox-2 inhibitors. Analysts also believe seven diagnostic launches in the quarter and the weak dollar will benefit Abbott's earnings.

Increased demand for non-Cox-2 inhibitors boosted sales of Abbott's painkiller Mobic following an FDA public health advisory on the Cox-2 class of drugs that warned of an increased risk of heart attack and stroke. The FDA asked doctors to exercise caution when prescribing the drugs, which include

Merck's

(MRK) - Get Report

Vioxx and

Pfizer's

(PFE) - Get Report

Bextra. Both drugs have been voluntarily withdrawn by the companies.

For the quarter, Abbott expects one-time charges of one cent a share, related to acquisitions in 2004 and minor restructuring charges. In the first quarter of last year, Abbott announced one-time charges amounting to 5 cents a share related to acquisitions and the spinoff of its hospital products group, Hospira.

Bear Stearns analyst Rick Wise expects the company will report 165% sales growth for Mobic, a nonsteroidal anti-inflammatory drug licensed from Germany's

Boehringer Ingelheim

. "Mobic is benefiting from Vioxx withdrawal and reduced Celebrex demand," Wise says.

Wise also predicts 98% growth in sales of the drug Humira, a treatment for the inflammation and joint destruction of rheumatoid arthritis, psoriatic arthritis and Crohn's disease. Humira works by targeting the protein tumor necrosis factor alpha, or TNF-a, which is overproduced in those with these diseases. Abbott has 30% of the self-injectable anti-TNF-a market.

Wise estimates worldwide first-quarter sales of Mobic at $273 million compared with $103 million a year ago. Abbott co-promotes Mobic with Boehringer Ingelheim. Wise sees sales of the cholesterol-lowering drug Tricor at $216 million, compared with $166 million last year. Sales of Flomax, which treats noncancerous enlargement of the prostate gland, should be at $224 million, compared with $217 million last year, he says. Bear Stearns says it is affiliated with a specialist who makes a market in Abbott's common stock.

J.P. Morgan's Michael Weinstein, however, says the current gross margin on Flomax has dropped from 30% to 6% since the company agreed to give back marketing rights to Boehringer Ingelheim while continuing to distribute and recognize revenue on the drug until 2007. Weinstein says Abbott will lose about $50 million in gross profit in the first quarter due to this agreement.

Weinstein predicts a 10% increase in sales of the protease inhibitor Kaletra for the first quarter and a 3% increase in sales of neurological drug Depakote, driven mainly by price increases. J.P. Morgan says it does and seeks to do business with the companies it covers.

Though Abbott outperformed the Amex index of drug stocks in the first quarter -- it gained 0.5% compared with a 0.6% loss for the index -- the Illinois-based company's shares could face pressure now that

Andrx

(ADRX)

and

Ranbaxy Labs

plan to sell generic equivalents of Abbott's antibiotic Biaxin after it loses patent protection on May 23.

The generic drug companies have received approval from the Food and Drug Administration to sell an immediate-release form of the generic clarithromycin. Abbott is fighting to delay approval for generic versions of the extended release Biaxin XL, which accounts for 65% of Biaxin sales.

"Should Abbott be able to hold off XL generics, it could mean a more immediate catalyst for the shares," says J.P. Morgan's Weinstein.

Abbott also is making progress toward the launch of its drug-eluting stent -- a market dominated by

Boston Scientific

(BSX) - Get Report

,

Johnson & Johnson,

(JNJ) - Get Report

.

Abbott shares jumped 2% last week on word the FDA gave the company the OK to begin trials on its Zomaxx stent -- a mesh tube that props open arteries that have been cleared of the plaque that can cause heart attacks. The company hopes to launch an approved product by the second quarter of 2007.

Abbott's shares were up 12 cents recently to $47.98 -- close to their 52-week high of $48.49.