Symmetrical Sequential Stopper for a Multi-Chamber Medical Injection Device

A sequential stopper configured to be positioned inside a barrel of a multi-chamber injection device for injecting at least one fluid through a distal end of the barrel, the sequential stopper comprising:

• a membrane comprising a proximal face and a distal face, the membrane being configured to separate a first, distal chamber of the barrel from a second, proximal chamber of the barrel, with the membrane including at least a slit extending therethrough between the proximal face and the distal face, with the slit configured to selectively create a fluid path through the membrane from the proximal face to the distal face depending on the pressure exerted by a composition onto the proximal face of the membrane for transferring fluid only from the proximal chamber to the distal chamber;
• and
• a lateral wall joined to the membrane to define a distal cavity and a proximal cavity, the lateral wall comprising a sealing surface including a plurality of circumferential ribs configured to sealingly engage the inner surface of the barrel;
• wherein the sequential stopper comprises a symmetrical stopper where the proximal face and the distal face have a corresponding configuration and wherein the membrane is positioned intermediate between a distal end and a proximal end of the sequential stopper.