It is described an aqueous, sterile, ready-to-use pharmaceutical composition suitable for parenteral administration by infusion for the treatment of cardiac conditions, being packaged in a sealed container, having a pH between 3.5 and 6.5 and comprising: a) 0.1 to 100 mg/ml methyl-3- [4-(2-hydroxy-3- isopropylamino)propoxy] phenylpropionate hydrochloride (esmolol hydrochloride) ； b) 0.01 to 0.5 M buffering agent； and c) 1 to 100 mg/ml osmotic-adjusting agent selected from at least one of sodium chloride, dextrose, sodium bicarbonate, calcium chloride, potassium chloride, sodium lactate, Ringer's solution and lactated Ringer's solution； a method for preparing this composition.It is described an aqueous, sterile, ready-to-use pharmaceutical composition suitable for parenteral administration by infusion for the treatment of cardiac conditions, being packaged in a sealed container, having a pH between 3.5 and 6.5 and comprising: a) 0.1 to 100 mg/ml methyl-3- [4-(2-hydroxy-3- isopropylamino)propoxy] phenylpropionate hydrochloride (esmolol hydrochloride) ； b) 0.01 to 0.5 M buffering agent； and c) 1 to 100 mg/ml osmotic-adjusting agent selected from at least one of sodium chloride, dextrose, sodium bicarbonate, calcium chloride, potassium chloride, sodium lactate, Ringer's solution and lactated Ringer's solution； a method for preparing this composition.
