A medication delivery device, comprising: a housing defined about a longitudinal axis (A-A), the housing including one or more housing rack teeth (134A, 134B); a plunger (64, 64a) having an elongated body with an end to drive a piston disposed within a medication cartridge barrel, the body including a plurality of ratchet teeth (74, 74a) disposed longitudinally spaced from one another; a plunger drive system configured to distally advance the plunger (64, 64a), the plunger drive system including an output drive member (68, 68a) having one or more pawled ends movably coupled with the ratchet teeth (74, 74a) of the plunger (64, 64a), the output drive member having one or more drive teeth (82, 82a, 84, 84a), at least one pinion drive (66, 66a, 67, 67a) engaged with the drive teeth of the output drive member and the housing rack teeth (13A, 134B) of the housing, and an actuator having a coupling end coupled to the at least one pinion drive, the actuator having a unitary piece body extending between a button end and the coupling end disposed within the housing, the actuator longitudinally movable between an extended position for dose setting and a retracted position for dose delivery, wherein, in response to movement of the actuator to the extended position from the retracted position, rotation of the at least one pinion drive (66, 66a, 67, 67a) in a first direction along the drive teeth (82, 82a, 84, 84a) is configured to axially translate the output drive member (68, 68a) relative to the plunger (64, 64a), with the one or more pawled ends of the output drive member sliding along the ratchet teeth (74, 74a) of the plunger (64, 64a), wherein, in response to movement of the actuator to the retracted position from the extended position, rotation of the at least one pinion drive (66, 66a, 67, 67a) in a second direction along the drive teeth (82, 82a, 84, 84a) is configured to axially translate the output drive member (68, 68a), with the one or more pawled ends of the output drive member in engagement with the ratchet teeth (74, 74a) of said plunger (64, 64a) to prevent said output drive member from translating axially relative to said plunger, thereby advancing the plunger in a distal direction, characterized in that the at least one pinion drive includes a first pinion drive member (67, 67a) and a second pinion drive member (66, 66a) disposed along opposite sides of the output drive member (68, 68a), wherein the drive teeth comprises a first rack (82, 82a) and a second rack (84, 84a) defined by the output drive member, wherein the first pinion drive member (67, 67a) is engaged with the first rack (82, 82a), and the second pinion drive member (66, 66a) is engaged with the second rack (84, 84a). a housing defined about a longitudinal axis (A-A), the housing including one or more housing rack teeth (134A, 134B); a plunger (64, 64a) having an elongated body with an end to drive a piston disposed within a medication cartridge barrel, the body including a plurality of ratchet teeth (74, 74a) disposed longitudinally spaced from one another; a plunger drive system configured to distally advance the plunger (64, 64a), the plunger drive system including an output drive member (68, 68a) having one or more pawled ends movably coupled with the ratchet teeth (74, 74a) of the plunger (64, 64a), the output drive member having one or more drive teeth (82, 82a, 84, 84a), at least one pinion drive (66, 66a, 67, 67a) engaged with the drive teeth of the output drive member and the housing rack teeth (13A, 134B) of the housing, and an actuator having a coupling end coupled to the at least one pinion drive, the actuator having a unitary piece body extending between a button end and the coupling end disposed within the housing, the actuator longitudinally movable between an extended position for dose setting and a retracted position for dose delivery, wherein, in response to movement of the actuator to the extended position from the retracted position, rotation of the at least one pinion drive (66, 66a, 67, 67a) in a first direction along the drive teeth (82, 82a, 84, 84a) is configured to axially translate the output drive member (68, 68a) relative to the plunger (64, 64a), with the one or more pawled ends of the output drive member sliding along the ratchet teeth (74, 74a) of the plunger (64, 64a), wherein, in response to movement of the actuator to the retracted position from the extended position, rotation of the at least one pinion drive (66, 66a, 67, 67a) in a second direction along the drive teeth (82, 82a, 84, 84a) is configured to axially translate the output drive member (68, 68a), with the one or more pawled ends of the output drive member in engagement with the ratchet teeth (74, 74a) of said plunger (64, 64a) to prevent said output drive member from translating axially relative to said plunger, thereby advancing the plunger in a distal direction, characterized in that the at least one pinion drive includes a first pinion drive member (67, 67a) and a second pinion drive member (66, 66a) disposed along opposite sides of the output drive member (68, 68a), wherein the drive teeth comprises a first rack (82, 82a) and a second rack (84, 84a) defined by the output drive member, wherein the first pinion drive member (67, 67a) is engaged with the first rack (82, 82a), and the second pinion drive member (66, 66a) is engaged with the second rack (84, 84a).