Two-chamber drug delivery device comprising a separating membrane

An automatic two-chamber injector for delivery of a drug which comprises a mixture of a lint substance and a second substance, the device comprising a barrel having a first end with a receiving portion for an injection needle and a second end with a slideable plunger, the barrel comprising a first chamber which houses the first substance, a second chamber which houses the second substance, a peelable membrane which in a first disposition thereof is welded to a surface of the first chamber so as to close the first chamber off from the second chamber to prevent mixture of the first and second substance;

• the membrane having a laminate structure, and a mechanism operable to displace the membrane from the first disposition to a second disposition in which the first and second substances are able to be mixed, wherein the laminate structure of the membrane comprises:
• a barrier material comprising a polymer selected from the group consisting of polychlorotrifluoroethylene, a copolymer of polychlorotrifluoroethylene, polyvinylidene chloride, a copolymer of polyvinlylidene chloride, and a silicon oxide;
• an outer layer comprising a material through which the membrane is welded to the surface of the first chamber, wherein the outer layer of the membrane and at least the surface of the first chamber to which the outer layer is welded are respectively formed of materials which provide a weld joint there between;
• and
• a first layer of a polyester material arranged between the barrier material and the outer layer,
• wherein said weld joint is of a strength which enables the membrane to be brought to the second disposition by peeling of the membrane off the first chamber, and further wherein the mechanism is adapted in use to cause the membrane to be displaced from the first disposition to the second disposition by peeling of the membrane off the first chamber.