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Dual-chamber injection cartridge

  • US 5,472,422 A
  • Filed: 02/24/1994
  • Issued: 12/05/1995
  • Est. Priority Date: 07/07/1992
  • Status: Expired due to Term
First Claim
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1. A method for manufacturing an injectable preparation of a pharmaceutically active agent suitable for storage in a dual-chamber injection cartridge, said method comprising the steps of:

  • A. providing a dual chamber injection cartridge including a cartridge barrel having a front end and a rear end;

    a front chamber in a vicinity of said front end of said barrel for a solid component of an injectable preparation;

    a rear chamber in a vicinity of said rear end of said barrel for a liquid component of an injectable preparation;

    a displaceable front piston of a resilient material for separating said front chamber and said rear chamber;

    a closure for sealing said front end of said barrel;

    a constriction arranged in said barrel between said front end and said rear end, said constriction having a non-circular cross-section; and

    an openable bypass connection for permitting a passage of liquid from said rear chamber to said front chamber, wherein prior to opening said bypass connection said front piston is positioned between said constriction and said rear end of said barrel, said constriction exerting a resistance against a displacement of said front piston in a direction of said front end of said barrel when said piston is in a vicinity of said constriction, and such that said constriction prevents said front piston from being displaced toward said front end of said barrel when a vacuum exists in said front chamber and a pressure in a vicinity of atmospheric pressure exists in said rear chamber, and wherein said front piston is deformed while being displaced through said constriction in a direction of said front end of said barrel while overcoming said resistance, said deformation establishing said liquid bypass connection;

    B. filling said rear chamber of said injection cartridge with said liquid component of the injectable preparation;

    C. sealing said rear chamber;

    D. charging a solution of the pharmaceutically active agent in said front chamber of said injection cartridge;

    E. subjecting said injection cartridge to a freeze-drying process prior; and

    F. sealing said front chamber of said injection cartridge.

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