Simplified disposable needle-free injection apparatus and method

A needle-free injection system comprising:

• a cartridge for holding liquid drug prior to injection, the cartridge having a rear end and a front end;
• a plug mounted to the front end of the cartridge, the plug including a channel and a body and a flange that extends rearwardly into the cartridge;
• a displaceable valve positioned within the channel prior to injection;
• and
• a nozzle portion for receiving liquid drug from the glass cartridge for injection, the nozzle portion including an injection orifice and a drug chamber having a valve seat designed to receive the valve to facilitate injection of liquid drug through the injection orifice.

A needle-free injection system comprising:

• a cylindrical glass cartridge for holding liquid drug prior to injection, the cartridge having a rear end and a front end and a longitudinal axis;
• a nozzle portion defining an injection orifice at a front end thereof for injecting liquid drug received from the glass cartridge;
• a plug mounted to and having a portion positioned forward of the front end of the cartridge, the plug defining a narrowed throat and including a channel in coaxial alignment with the longitudinal axis of the cartridge and the injection orifice, the channel being smaller in dimension than the cartridge;
• and
• a displaceable valve positioned within the channel prior to injection.

A needle-free injection system comprising:

• a cylindrical glass cartridge for holding liquid drug prior to injection, the cartridge having a rear end and a front end and a longitudinal axis;
• a nozzle portion defining an injection orifice at a front end thereof for injecting liquid drug received from the glass cartridge;
• a plug mounted to the front end of the cartridge, the plug including a channel in coaxial alignment with the longitudinal axis of the cartridge and the injection orifice, the channel being smaller in dimension than the cartridge;
• wherein the plug fits tightly against the cartridge and the plug includes a body that exerts a rearward force on the cartridge and includes a flange that extends rearwardly into the cartridge, exerting an outward force on an interior surface of the cartridge;
• and
• a displaceable valve positioned within the channel prior to injection.

A needle-free injector comprising:

• a housing for holding various injector components;
• a gas cartridge mounted in the housing for providing a source of pressurized gas;
• a mechanism for piercing the gas cartridge upon demand, the mechanism being mounted in the housing such that it is moveable with respect to the gas cartridge;
• a drug cartridge mounted in the housing for storing liquid drug prior to injection, the drug cartridge having a plunger initially positioned at a rearward portion thereof;
• an injection orifice defined in a front end of the housing and having a fluid inter connection with the drug cartridge;
• a gas piston for converting gas pressure from the gas cartridge into a forward force exerted on the plunger;
• and
• a seal system mounted in the housing for preventing pressurized gas leaving the pierced gas cartridge from reaching the gas piston prior to injection;
• wherein the seal system includes a first axial gas channel extending forwardly from the gas cartridge, a first radial gas channel extending radially outwardly from the axial gas channel;
• and an axially displaceable seal that is displaceable from a first position covering the first radial gas channel to a second position where the first radial gas channel is uncovered.

A method for filling a cartridge with liquid drug for use in a needle-free injection device, comprising:

• providing a plug with a front and a rear and having a rearwardly extending portion and a central channel;
• positioning a valve in the central channel at a point set back from the front of the plug;
• providing a cylindrical glass drug cartridge having a front and a rear;
• positioning a plunger in the rear end of the cartridge;
• filling the cartridge with liquid drug;
• and
• inserting the plug with the valve disposed therein in the front end of the cartridge, and simultaneously having the rearwardly extending portion displace some of the liquid drug in the cartridge so that the liquid drug enters the channel, displacing the valve forwardly within the channel.