The USPTO awards patents no. 8,754,257 and no. 8,754,258 to Keryx Biopharmaceuticals (KERX +2.2%) covering a form of ferric citrate with a specific intrinsic dissolution rate. Ferric citrate is the active ingredient in Zerenex. The '257 patent also contains claims pertaining to the dosing and daily administration regimen of Zerenex that is included in the company's NDA which is currently under FDA review.
The patents, which expire in 2024, increase the Zerenex-related patents to seven.