US FDA rejects Merck's Vioxx successor

NEW YORK, Apr 28 (Reuters) Merck&Co. said that US regulators have rejected its arthritis drug Arcoxia, the drugmaker's follow-up to Vioxx, informing the company it cannot be approved without new supportive data.

The rejection by the U.S. Food and Drug Administration came after an advisory panel to the agency earlier this month recommended against Arcoxia's approval.

Members of the U.S. advisory panel, by a lopsided vote, had spurned 30-milligram and 60-milligram doses of the drug, saying the medicine could damage the heart and had not shown any benefits over the approximately 20 pain relievers already on the market.

U.S. studies of 90-milligram doses of Arcoxia -- the dose widely used overseas to treat rheumatoid arthritis -- have linked Arcoxia to elevated rates of blood pressure, tissue swelling that can lead to heart problems, and congestive heart failure.

The FDA turned down Arcoxia in a so-called non-approvable letter, saying it could not be approved for osteoarthritis without ''additional data in support of the benefit-to-risk profile for the proposed doses of Arcoxia,'' Merck said on Friday. Osteoarthritis is the most common form of arthritis, caused by wear and tear of the joints.

''We're evaluating the letter,'' said Merck spokesman Ron Rogers, who declined to say whether Merck will renew its efforts to win marketing approval.

''Our regulatory strategy is proprietary,'' he said.

Merck had been awaiting U.S. approval of the pill as a treatment for osteoarthritis since December 2003. The pill is already sold in more than 60 other countries.

The company had been evaluating whether to also seek U.S.

approval of the product for rheumatoid arthritis, the less-common but often-crippling form of arthritis in which an overactive immune system attacks joints.

The same cardiovascular side effects that emerged in the U.S. Arcoxia trials had been seen in studies of Vioxx, which Merck withdrew in September 2004 after it was linked to heart attacks among long-term users. Both Vioxx and Arcoxia target the COX-2 enzyme involved in inflammation.

Despite the negative safety trends seen in U.S. trials of Arcoxia, Rogers said Merck remains comfortable about the safety of the medicine in overseas markets and has provided all information about the U.S. trials to European health authorities.

He said he was not immediately able to determine how many countries, if any, had access to the unfavorable U.S. data before they approved Arcoxia.

''Right now we have no plans to change our marketing plans for Arcoxia outside the United States,'' he said.

Merck was hoping that Arcoxia, which had 2006 sales of 5 million, could win far bigger revenue if approved in the United States -- the world's most profitable market for prescription drugs.

Shares of Merck closed down 1.1 percent to .86 on the New York Stock Exchange, amid a slight decline for the drug sector.

REUTERS DKS BST0452