Merck & Co. received a "not approvable" letter from FDA for its MK-0524A (niacin/laropiprant) new drug application, the firm said April 28. The agency also rejected the firm's proposed trade name, Cordaptive .

This is the second such action Merck has received in as many business days for a drug/drug combination. FDA sent Merck/Schering-Plough a not approvable letter April 25 for its combination of Claritin/Singulair (loratadine/montelukast) to treat allergy symptoms, both seasonal and perennial (¹ Also see "Merck-Schering Claritin/Singulair Combo “Not Approvable” At FDA" - Pink Sheet, 25 April, 2008.).

Merck's Cordaptive NDA sought an indication for treatment of primary hypercholesterolemia or mixed dyslipidemia. The PDUFA date was April 29.

The firm plans to meet with FDA and submit additional information so the agency can further evaluate the compound's benefit/risk profile, Merck said in a statement.

Merck did get some good news during the week. Cordaptive received a marketing approval recommendation from the European Medicines Agency's Committee for Medicinal Products for Human Use on April 24.

"We firmly believe that MK-0524A provides physicians with an important option to manage their patients' cholesterol," Peter S. Kim, president of Merck Research Laboratories, said in a statement. "We will continue to pursue approval within individual markets in the EU and around the world," he added.

Merck said it would pursue an alternative trade name, Tredaptive , for use in the U.S. "at the appropriate time."

Niacin lowers bad cholesterol and boosts good cholesterol, but causes an annoying flushing, or blushing, side effect caused by prostaglandin D2 binding to the prostaglandin D receptor. Laropiprant selectively blocks this binding, thus reduces flushing.

The negative FDA decision for Cordaptive is a positive for Abbott's HDL cholesterol booster Niaspan (niacin). Sales of Niaspan jumped 24.2 percent to $176 million in the first quarter, fueled by the launch last year of a new film-coated tablet that offers dosing advantages (² Also see "Abbott Won’t Shrink From Competitor Merck’s Cordaptive" - Pink Sheet, 16 April, 2008.).

Niaspan would compete favorably against Cordaptive based on the former drug's safety record and efficacy, despite the flushing side effect, Abbott execs said during the firm's first quarter earnings call April 16.

Most Wall Street analysts assumed full approval of the Cordaptive combination in financial models, Sara Michelmore of Cowen and Company said in an April 28 note published before Merck's after-the-bell announcement. However, she said, "Approval of Cordaptive is not a given because some safety concerns have been raised about the laropiprant portion of the product."

-Pamela Taulbee (p.taulbee@elsevier.com)

Merck: Second “Not Approvable” Letter In Two Days – This Time, Cordaptive

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