A stable liquid composition comprising warfarin sodium, glycerin, an alcohol such as ethanol, and a pH buffer such as a phosphate buffer providing a pH above 7 is provided. The stability of the composition is characterized by the amount of warfarin sodium in the composition degraded after 1 month at room temperature, which is 5% or less. A method for preparing the composition and a method for providing an anti-coagulant therapy are also disclosed.