An automatic injection device (10) for containing a preloaded charge of medicament for automatically administering the medicament upon actuation thereof, the device comprising: a housing (110) having an interior chamber (150), the inner chamber (150) includes a dry compartment (152) for containing a dry medicament component and a wet compartment (151) for containing a liquid component for mixing with said dry component； a sealing structure (160) between the dry compartment (152) and the wet compartment (151), the seal structure (160) is initially in a sealing condition that maintains the sealed dry compartment (152) of the liquid compartment (151 )； a needle assembly (140) for dispensing a drug loading from the housing (110)； a plunger (170) disposed within the chamber (150) and movable through the chamber (150) to force drug loading through the needle assembly (140)； and an activation assembly (120) received within the housing (110) and including a stored energy source (250), wherein activation of the activation assembly (120) releases the stored energy from the stored energy source (250 )； characterized in that: the sealing structure (160) comprises a member outer seal (180), a flow path (167), a plug inner seal (166) movable relative to the member outer seal (180), and a filter or membrane (164) that creates a laminar flow of fluid when the liquid component passes through the sealing structure (160) from the wet compartment (151) to the dry compartment (152)； cap inner seal (166) seals the wet compartment (151) the dry compartment (152) in the sealing state and allows the contents of the wet and dry compartments (151, 152) are mixed when they move to a position mixing； and that: the release of the stored energy by the trigger assembly (120) causes: the plug inner seal (166) moves to the mixing position, which makes the sealing structure (160) from the state sealing a mixed state allowing said liquid component passes through the flow path (167) from the wet compar
