Plungers for drug delivery devices

An autoinjector device comprising:

• a housing;
• a syringe assembly at least partially received within the housing and including a syringe barrel with an annular sidewall extending between a first, open end and a second end having a dispensing opening;
• an actuating mechanism at least partially received within the housing and including a plunger received within the syringe barrel, the plunger comprising:
• a body portion having a sidewall, a leading surface, and a trailing surface, wherein the body portion does not include a cavity having an opening defined in the trailing surface configured to receive a plunger rod therein, and a ribbed portion comprising a plurality of ribs projecting radially outwardly from the sidewall of the body portion and spaced axially apart from one another, the plurality of ribs comprising at least a trailing rib and a leading rib, each of the ribs including an annular configuration and sized so that the ribs seal against an interior surface of the sidewall of the syringe barrel;
• a drive mechanism;
• and
• a drive member configured to be driven by the drive mechanism to push the plunger through the syringe barrel to the second end thereof to thereby force a medicament within the syringe barrel through the dispensing opening,
• the plunger having the plurality of ribs exhibiting a mean glide force in the range of approximately 0.4 to approximately 1.5 N, which represents a reduction in the mean glide force by at least 15% relative to a mean glide force of a plunger having a majority of the sidewall of the body portion contact the interior surface of the sidewall of the syringe barrel.

An on-body injector device comprising:

• a housing having an interior and a bottom wall within an opening extending therethrough, the housing configured to be secured to the tissue of a user;
• a reservoir with an annular sidewall extending between a first, open end and a second end having a dispensing opening;
• a drive mechanism including a plunger received within the reservoir, the plunger comprising:
• a body portion having a sidewall, a leading surface, and a trailing surface, wherein the body portion does not include a cavity having an opening defined in the trailing surface configured to receive a plunger rod therein, and a ribbed portion comprising a plurality of ribs projecting radially outwardly from the sidewall of the body portion and spaced axially apart from one another, the plurality of ribs comprising at least a trailing rib and a leading rib, each of the ribs including an annular configuration and being sized so that the ribs seal against an interior surface of the sidewall of the reservoir;
• a drive member configured to drive the plunger through the reservoir to the second end thereof;
• an insertion mechanism including a delivery member configured to shift from a retracted position within the housing to a deployed position extending outside of the housing through the opening thereof;
• a fluid pathway assembly configured to fluidly couple the reservoir to the insertion mechanism;
• and
• an actuator configured to cause the drive mechanism to drive the plunger through the reservoir to the second end thereof in response to an actuation thereof to thereby dispense medicament within the reservoir through the insertion mechanism,
• the plunger having the plurality of ribs exhibiting a mean glide force in the range of approximately 0.4 to approximately 1.5 N, which represents a reduction in the mean glide force by at least 15% relative to a mean glide force of a plunger having a majority of the sidewall of the body portion contact the interior surface of the sidewall of the chamber.