NEW PAIN RELIEVER APPROVED; VIOXX TO CHALLENGE DRUG FOR ARTHRITIS.

Byline: Randolph E. Schmid Associated Press 

The federal government approved Merck & Co.'s new pain drug Vioxx on Friday, setting up a high-stakes showdown with Monsanto and Pfizer's arthritis drug Celebrex, which this spring became the second fastest-selling new drug in history.

Vioxx, which was approved to treat osteoarthritis and general pain in adults, should be in pharmacies by mid-June.

Celebrex, which is indicated for patients with osteoarthritis and rheumatoid arthritis, has sold about 4.4 million prescriptions since introduced in January.

Vioxx's average wholesale price is $2.02 for 12.5 mg and 25 mg tablets, the same as Celebrex's standard dosage.

The number of potential customers for each drug is huge. The Arthritis Foundation estimates that osteoarthritis afflicts 15.8 million Americans, while about 2.1 million in the United States suffer from rheumatoid arthritis.

Analysts say that by 2002, both drugs could bring in annual sales topping $2 billion each.

Vioxx also will be available in liquid form, which is one of several ways Merck hopes to differentiate its drug from Celebrex.

``We think we are in great shape,'' said Wendy Dixon, Merck's vice president of marketing.

Monsanto officials said they are ready for Merck.

``We are confident we can compete with the label we have,'' said Jeff Bergau, a spokesman for Monsanto's drug division, called Searle.

In the tests on acute pain, Merck officials said the drug was tested and worked well on patients following extraction of wisdom teeth, patients undergoing hip or knee replacements and women with severe menstrual pain.