Flow communication unit with preservative

An assembly comprising (a) a cartridge with a drug-filled interior, (b) a flow conducting device, and (c) a flow communication unit adapted to provide flow communication between the cartridge and the flow conducting device,

• (a) the drug-filled cartridge comprising:
• an outlet sealed by a needle-penetrable septum,
• (b) the flow conducting device comprising:
• a hollow tubular structure with a skin-piercing distal end, and
• a proximal flow inlet,
• (c) the flow communication unit comprising:
• a proximal hollow needle adapted to penetrate the needle-penetrable septum,
• a first flow way in flow communication with the proximal needle and comprising pressure-controlled valve structure,
• a second flow way in flow communication with the first flow way,
• an amount of preservative arranged to react with a substance received by the second flow way, and
• distal flow communication structure adapted to provide flow communication between the second flow way and a flow conducting device flow inlet,
• whereby:
• a combined flow way can be established between the cartridge interior and the hollow tubular structure via at least two of the proximal needle, the first flow way, and second flow way, when the cartridge, the flow communication unit and the flow conducting device are connected to each other,
• the valve structure is controlled to open when the cartridge interior is pressurized, and
• the preservative can react with a substance introduced to the second flow way via the hollow tubular structure with a skin-piercing distal end;
• wherein the flow conducting device is a needle unit, wherein the hollow tubular structure is a hollow expelling needle with the skin-piercing distal end;
• wherein:
• the needle unit comprises the hollow tubular structure comprising a proximal portion with an open end forming the proximal flow inlet, and
• the second flow way is adapted to receive the tubular conduit proximal portion when the needle unit is connected to the flow communication unit;
• wherein:
• the second flow way is in the form of a conduit comprising an amount of preservative, the conduit being closed by a septum adapted to be penetrated by the tubular conduit proximal portion when the needle unit is connected to the flow communication unit.

A flow communication unit comprising:

• a proximal hollow needle adapted to penetrate a needle-penetrable septum,
• a first flow way in flow communication with the proximal needle and comprising pressure-controlled valve structure,
• a second flow way in flow communication with the first flow way,
• an amount of preservative arranged to react with a substance received by the second flow way, and
• distal flow communication structure adapted to provide flow communication between the second flow way and a flow conducting device flow inlet,
• a tubular conduit comprising a distal portion with an open end, the tubular conduit forming the second flow way, and
• a preservative unit comprising the amount of preservative and having a first axial position in which the tubular conduit distal portion is embedded in preservative, and a second axial position in which the tubular conduit distal portion protrudes distally from the preservative unit,
• wherein the preservative unit is moved from the first position to the second position when the needle unit is connected to the flow communication unit, the tubular conduit distal portion thereby providing the distal flow communication structure,
• wherein the valve structure is controlled to open when the proximal hollow needle is pressurized.