Patent ID: 8653139

Claim:
A drug substance preparation comprising (R)-(−)-2-(2-fluoro-4-biphenylyl) propionic acid, or a pharmaceutically acceptable salt thereof, as the active pharmaceutical ingredient, and between about 0.001% and about 3%, by weight, product-related impurities, wherein said product-related impurities comprise not more than about 0.5%, by weight, 2-(4-biphenylyl) propionic acid, or a salt thereof, and not more than about 2%, by weight, of the enantiomeric impurity (S)-(+)-2-(2-fluoro-4-biphenylyl) propionic acid, or a salt thereof, and not more than about 200 ppm of the process-related impurity, (R)-(+)-α-methylbenzylamine.