Feb 26 (Reuters) - Merck has received a letter that Hikma Pharmaceuticals US unit has sought a pre-patent expiry approval from the US FDA to sell a generic version of its Bridion injection, the drugmaker said in filing on Monday.

Merck said, on Feb. 5, it received the letter under the Hatch-Waxman Act, through which a company can seek FDA approval to market a copycat before the expiration of patents related to the brand-name drug.

Merck said in the filing that it is currently considering its options.

Both Merck and Hikma did not immediately respond to Reuters requests for comment.

Bridion, chemically known as sugammadex, is approved to reverse the effects of muscle relaxants used in surgery. The injection has a patent protection through at least Jan. 2026. (Reporting by Sriparna Roy in Bengaluru; Editing by Shailesh Kuber)