Abstract: The present invention has been made in an effort to more assuredly substitute oxygen in a vial. A gas substitution apparatus according to the exemplary embodiment of the present invention includes: a first gas substitution unit which seals a periphery of an opening of a vial disposed in a gas substitution section, and guides a flow of a first substitution gas to be supplied into the vial; and a second gas substitution unit which is coupled to an upper side of the first gas substitution unit, and guides a flow of a second substitution gas to be supplied directly into the vial.

Abstract: Provided is a composition of a ready-to-use injectable solution comprising pemetrexed or pharmaceutically acceptable salts thereof, containing pemetrexed; anhydrous sodium sulfite; and N-acetyl-L-cystein. With respect to use as an injectable preparation. The ready-to-use injectable solution composition is suitable for effective administration of pemetrexed since a melting process of main ingredients is not necessary before administration, and the composition can be used by being diluted immediately in a perfusate. In addition, the properties of the composition do not change even in long-term storage, and pharmaceutical stability is significantly improved by inhibiting related substances below a reference, whereby the composition can be stored in a liquid preparation state.