Devices and methods for delivering a lyophilized medicament

An apparatus, comprising:

• a housing defining a gas chamber;
• an energy storage member configured to produce a pressurized gas within the gas chamber when the energy storage member is actuated;
• a medicament container assembly disposed within the housing, the medicament container assembly including a container body and an elastomeric member disposed within the container body, a surface of the elastomeric member defining a first portion of a boundary of the gas chamber, the medicament container assembly including a delivery member coupled to a distal end portion of the container body, wherein the surface of the elastomeric member that defines the first portion of a boundary of the gas chamber is disposed within the container body;
• and
• a sealing assembly coupled to the medicament container assembly and disposed within the housing, a proximal surface of the sealing assembly defining a second portion of the boundary of the gas chamber, the sealing assembly configured to move within the housing from a first sealing assembly position to a second sealing assembly position in response to a first force exerted by the pressurized gas on the proximal surface of the sealing assembly, the elastomeric member configured to move within the container body to deliver a dose of a medicament from the container body via the delivery member in response to a second force exerted by the pressurized gas in direct contact with the surface of the elastomeric member disposed within the container body;
• and
• a vent assembly including a vent opening defined by the housing, the vent opening being configured to vent a portion of the pressurized gas to reduce at least the first force exerted by the pressurized gas to a magnitude that is less than a retraction force exerted on the sealing assembly by a bias member.

A method of delivering a dose of a medicament, comprising:

• actuating a medical injector such that an energy storage member produces a force by releasing a pressurized gas within an internal volume of a housing of the medical injector, the force exerted on a container assembly containing the dose of the medicament, the force causing the container assembly to move distally within the housing to cause a needle to extend from the housing, the movement of the container assembly compressing a retraction spring of the medical injector, the pressurized gas directly contacting a surface of an elastomeric member and causing the elastomeric member to move within a container body of the container assembly to deliver the dose of the medicament from the container body via the needle, the surface of the elastomeric member being disposed within the container body;
• initiating a venting of the internal volume via a vent opening defined by the housing, the vent opening being sized to maintain the force produced by the pressurized gas on the container assembly at a magnitude that is greater than a retraction force applied by the retraction spring onto the container assembly during a delivery time during which a final portion the dose of the medicament is delivered, the vent opening being sized to decrease the force produced by the pressurized gas to a magnitude that is less than the retraction force applied by the retraction spring concurrent with the delivery of the final portion of the dose;
• and
• retracting the needle via a proximal movement of the container assembly within the housing after the delivery time and in response to the force applied by the retraction spring.