UPDATE 1-Merck anesthesia-reversal agent faces new delay

March 15 (Reuters) - The U.S. Food and Drug Administration will not complete its review of Merck & Co's experimental medicine to reverse the effects of anesthesia until the second half of 2013, representing a three-month delay, the drugmaker.

Merck acquired the product, called sugammadex, through its merger in 2009 with Schering-Plough Corp. The product has faced numerous previous regulatory delays but is deemed by many analysts and doctors as one of the biggest advances in anesthesia in decades.

The FDA in 2008 said it could not approve sugammadex until Merck provided more clinical trial data related to allergic reactions and blood clots, possible side effects of the drug. Merck early this year said it had completed the necessary trials and that the FDA had accepted the company's resubmitted marketing application for the drug.

Merck spokeswoman Pam Eisele on Friday said the FDA, in notifying the drugmaker about the expected delay in making a decision on the drug, did not cite any new safety issues.

"We've maintained regular meetings and discussions with the FDA, with a commitment to making sugammadex available in the United States," she said.

The drug is already sold in 75 countries and had 2012 global sales of $261 million. That makes it a modest-sized product for Merck, the second-largest U.S. drugmaker.

Merck shares were down 0.6 percent in morning trading on the New York Stock Exchange.