An ink cartridge has a container main body 2 having a through hole 60 for making an ink storage chamber and an atmospheric open chamber 501 to communicate with each other, and an atmospheric open valve 601 having a valve body 65 capable of opening and closing the through hole 60 of the container main body 2 and an elastic member 62 capable of pressing the valve body 65 in a closed direction. The interface supports communication between any components having any difference in capacity and over any distance. The P2Y receptor agonist can be administered with therapeutic and adjuvant agents commonly used to treat edematous retinal disorders.