An injector (10,86), comprising: a prefilled syringe (18, 88) comprising: a container portion defining a fluid chamber (22, 106) containing a medicament; an injection-assisting needle disposed at the distal end of the fluid chamber (22, 106) having an injecting tip configured for piercing an insertion location and defining a fluid pathway in fluid communication with the fluid chamber (22, 106); and a plunger (28, 104) movable within the fluid chamber (22, 106); a housing (12, 108) that houses the prefilled syringe (18, 88) and comprises an outer housing and a guard that is movable with respect to the outer housing, wherein the guard comprises a distal surface and is configured to allow the needle to extend beyond the distal surface at a maximum distance of about 15 mm; a syringe support supportively mounting the prefilled syringe (18, 88) to the outer housing, such that the prefilled syringe (18, 88) remains stationary within the outer housing and is fixed thereto; a syringe cushion (38, 118) associated with the syringe support and the prefilled syringe (18, 88) to compensate for shape irregularities of the pre-filled syringe (18, 88); and an energy source configured for biasing the plunger (28, 104) with a force selected to produce an injecting pressure in the medicament in the fluid chamber (22, 106) that substantially remains from about 5.5 Bar (80 p.s.i.) to about 68.9 Bar (1000 p.s.i.) during injection of the medicament to inject the medicament from the fluid chamber (22,106) through the needle to an injection site, wherein a penetration depth and the injecting pressure are sufficient to substantially prevent backflow of the injected medicament. a container portion defining a fluid chamber (22, 106) containing a medicament; an injection-assisting needle disposed at the distal end of the fluid chamber (22, 106) having an injecting tip configured for piercing an insertion location and defining a fluid pathway in fluid communication with the fluid chamber (22, 106); and a plunger (28, 104) movable within the fluid chamber (22, 106); a housing (12, 108) that houses the prefilled syringe (18, 88) and comprises an outer housing and a guard that is movable with respect to the outer housing, wherein the guard comprises a distal surface and is configured to allow the needle to extend beyond the distal surface at a maximum distance of about 15 mm; a syringe support supportively mounting the prefilled syringe (18, 88) to the outer housing, such that the prefilled syringe (18, 88) remains stationary within the outer housing and is fixed thereto; a syringe cushion (38, 118) associated with the syringe support and the prefilled syringe (18, 88) to compensate for shape irregularities of the pre-filled syringe (18, 88); and an energy source configured for biasing the plunger (28, 104) with a force selected to produce an injecting pressure in the medicament in the fluid chamber (22, 106) that substantially remains from about 5.5 Bar (80 p.s.i.) to about 68.9 Bar (1000 p.s.i.) during injection of the medicament to inject the medicament from the fluid chamber (22,106) through the needle to an injection site, wherein a penetration depth and the injecting pressure are sufficient to substantially prevent backflow of the injected medicament.