A system for delivering a pharmaceutical product from a cartridge (155,155'), comprising: an injector body (105, 105', 150") having a side wall (110, 110') having a proximal end portion (106, 106'), a distal end portion (107, 107'), an inner surface (120, 120') and an outer surface (115, 115'), said inner surface (120, 120') of said side wall (110, 110') defining a cavity (125, 125') for receiving at least a portion of said cartridge (150, 155'); one or more retention members (135, 135') disposed on said outer surface (115. 115') of said injector body (105, 105'): a plunger rod (130, 130', 130") having a proximal end portion (131, 131') and a distal end portion (132, 132') and one or more receiving members (133, 35'), between said proximal end portion (131, 131') and said distal end portion (132, 132'), adapted to engage said retention members; wherein said one or more retention members (135, 135') and said one or more receiving members (133, 35') are constructed to cooperatively retain said plunger rod (130, 130') adjacent to the outer surface (115, 115') of said injector body (105, 105') when said plunger rod (130,130') is in a first position, characterized in that said one or more retention members (135, 135') and said one or more receiving members (133, 35') are constructed to cooperatively release said plunger rod (130, 130') from said injector body (105, 105') when said plunger rod is transitioned axially toward said distal end (107, 107') of said injector body to a second position; and in that said plunger rod (130, 130') has a pushing surface (152, 152') for engaging said cartridge (155, 155') positioned in said cavity (125, 125') of said injector body (105, 105'), said pushing surface (152, 152') constructed to move said cartridge (155, 155') axially distally from said first position to said second position to simultaneously activate said cartridge (155, 155', 155"), and a tamper-evident band (194") having a first portion secured to said injector body (150, 150', 150") and a second portion (208") secured to said plunger rod (130, 130', 130"), wherein one of said first portion and said second portion (208") of said tamper-evident band (194") has a frangible portion (210") that is adapted to fracture upon movement of said plunger rod with respect to said injector body. an injector body (105, 105', 150") having a side wall (110, 110') having a proximal end portion (106, 106'), a distal end portion (107, 107'), an inner surface (120, 120') and an outer surface (115, 115'), said inner surface (120, 120') of said side wall (110, 110') defining a cavity (125, 125') for receiving at least a portion of said cartridge (150, 155'); one or more retention members (135, 135') disposed on said outer surface (115. 115') of said injector body (105, 105'): a plunger rod (130, 130', 130") having a proximal end portion (131, 131') and a distal end portion (132, 132') and one or more receiving members (133, 35'), between said proximal end portion (131, 131') and said distal end portion (132, 132'), adapted to engage said retention members; wherein said one or more retention members (135, 135') and said one or more receiving members (133, 35') are constructed to cooperatively retain said plunger rod (130, 130') adjacent to the outer surface (115, 115') of said injector body (105, 105') when said plunger rod (130,130') is in a first position, characterized in that said one or more retention members (135, 135') and said one or more receiving members (133, 35') are constructed to cooperatively release said plunger rod (130, 130') from said injector body (105, 105') when said plunger rod is transitioned axially toward said distal end (107, 107') of said injector body to a second position; and in that said plunger rod (130, 130') has a pushing surface (152, 152') for engaging said cartridge (155, 155') positioned in said cavity (125, 125') of said injector body (105, 105'), said pushing surface (152, 152') constructed to move said cartridge (155, 155') axially distally from said first position to said second position to simultaneously activate said cartridge (155, 155', 155"), and a tamper-evident band (194") having a first portion secured to said injector body (150, 150', 150") and a second portion (208") secured to said plunger rod (130, 130', 130"), wherein one of said first portion and said second portion (208") of said tamper-evident band (194") has a frangible portion (210") that is adapted to fracture upon movement of said plunger rod with respect to said injector body.