The present invention relates to an infusion dosage form comprising (i) an aqueous solution of morphine or its pharmaceutically acceptable salt as a sole active ingredient in a concentration ranging from about 0.1 mg/ml to about 10.0 mg/ml, filled in containers in volumes ranging from about 50 ml to about 250 ml, and having dissolved oxygen content of less than 2 ppm, (ii) the container being surrounded by an outer covering, and (iii) an inert gas or vacuum is present in the space between the container and outer covering, wherein the infusion dosage form is sterilized by autoclaving and is stable upon autoclaving, and further wherein the space between the container and outer covering does not have an oxygen scavenger pouch before or during autoclaving.