A therapeutic agent delivery system (10, 210), comprising: a housing (12, 214) having a distal end portion; a therapeutic agent delivery assembly carried by the housing (12, 214), the therapeutic agent delivery assembly comprising: a chamber (148, 242) comprising a passageway; a therapeutic agent carried in the passageway; a needle (18, 238) in communication with the passageway; the therapeutic agent delivery assembly being translatable relative to the housing (12, 214) from a stowed configuration to a deployed configuration, in the deployed configuration the needle (18, 238) at least partially extending distally from the distal end portion of the housing (12, 214); a user input (22, 218) configured to be actuated by a user, actuation of the user input (22, 218) translating the therapeutic agent delivery assembly from the stowed configuration to the deployed configuration; an input restraint being rotatable relative to the housing (12, 214) from a first rotational configuration to a second rotational configuration, in the first rotational configuration the input restraint inhibiting actuation of the user input (22, 218), and in the second rotational configuration the input restraint permitting actuation of the user input (22, 218); and a sleeve (24, 212) being translatable relative to the housing (12, 214) from an exposed configuration to a retracted configuration, in the exposed configuration the sleeve (24, 212) at least partially extending distally from the distal end portion of the housing (12, 214), and the sleeve (24, 212) rotating the input restraint from the first rotational configuration to the second rotational configuration when translating from the exposed configuration to the retracted configuration; wherein the therapeutic agent delivery assembly further comprises a pressure generating actuator, wherein actuation of the user input (22, 218) causes the pressure generating actuator to pressurize the therapeutic agent, deliver the therapeutic agent from the passageway to the needle (18, 238), and discharge the therapeutic agent from the needle (18, 238); and wherein the pressure generating actuator comprises a mixing chamber (106, 108) and a shuttle carried by the mixing chamber (106, 108), and the pressure generating actuator pressurizes the therapeutic agent upon the shuttle rotating relative to the mixing chamber (106, 108). a housing (12, 214) having a distal end portion; a therapeutic agent delivery assembly carried by the housing (12, 214), the therapeutic agent delivery assembly comprising: a chamber (148, 242) comprising a passageway; a therapeutic agent carried in the passageway; a needle (18, 238) in communication with the passageway; a chamber (148, 242) comprising a passageway; a therapeutic agent carried in the passageway; a needle (18, 238) in communication with the passageway; the therapeutic agent delivery assembly being translatable relative to the housing (12, 214) from a stowed configuration to a deployed configuration, in the deployed configuration the needle (18, 238) at least partially extending distally from the distal end portion of the housing (12, 214); a user input (22, 218) configured to be actuated by a user, actuation of the user input (22, 218) translating the therapeutic agent delivery assembly from the stowed configuration to the deployed configuration; an input restraint being rotatable relative to the housing (12, 214) from a first rotational configuration to a second rotational configuration, in the first rotational configuration the input restraint inhibiting actuation of the user input (22, 218), and in the second rotational configuration the input restraint permitting actuation of the user input (22, 218); and a sleeve (24, 212) being translatable relative to the housing (12, 214) from an exposed configuration to a retracted configuration, in the exposed configuration the sleeve (24, 212) at least partially extending distally from the distal end portion of the housing (12, 214), and the sleeve (24, 212) rotating the input restraint from the first rotational configuration to the second rotational configuration when translating from the exposed configuration to the retracted configuration; wherein the therapeutic agent delivery assembly further comprises a pressure generating actuator, wherein actuation of the user input (22, 218) causes the pressure generating actuator to pressurize the therapeutic agent, deliver the therapeutic agent from the passageway to the needle (18, 238), and discharge the therapeutic agent from the needle (18, 238); and wherein the pressure generating actuator comprises a mixing chamber (106, 108) and a shuttle carried by the mixing chamber (106, 108), and the pressure generating actuator pressurizes the therapeutic agent upon the shuttle rotating relative to the mixing chamber (106, 108).