Hazardous agent injection system

1. A hazardous agent injection system comprising:

methotrexate in an amount of about 0.02 ml to about 4.0 ml and at a concentration of about 7.5 mg/ml to about 150 mg/ml;

a powered injector comprising:

a container containing the methotrexate;

an injection outlet member fluidly coupled with the container and configured to deliver the methotrexate to a patient subcutaneously;

a firing mechanism coupled to the container and configured to expel the methotrexate from the container through the injection outlet member for injecting the methotrexate;

an energy source coupled to the firing mechanism and configured to power the firing mechanism; and

a trigger mechanism coupled to the firing mechanism and configured to activate the firing mechanism,

wherein the powered injector is configured to eject the methotrexate from the injection outlet member such that one or more of confidence intervals of (a) the maximum concentration of methotrexate in blood plasma of the patient following administration of a dose of the methotrexate to the patient with the hazardous agent injection system, (b) the time to reach the maximum concentration of methotrexate in blood plasma of the patient following administration of a dose of the methotrexate to the patient with the hazardous agent injection system and (c) area under a curve of a concentration of methotrexate in blood plasma of the patient following administration of a dose of the methotrexate to the patient with the hazardous agent injection system falls between about 80% and about 125% of a measured confidence interval of an equivalent dose of methotrexate delivered by a hand-powered syringe, and

wherein the powered injector is configured to subcutaneously inject the methotrexate at a pressure of at least about 80 psi.

2. The hazardous agent injection system of claim 1 , wherein the powered injector is a jet injector.

3. The hazardous agent injection system of claim 2 , wherein the injection outlet member includes an injection-assisting needle, a gauge of the injection-assisting needle being selected from 26 gauge and a higher gauge number.

4. The hazardous agent injection system of claim 1 , wherein the powered injector is configured to inject the methotrexate such that the methotrexate is injected at a flow rate of at least about 0.5 ml/sec.

5. The hazardous agent injection system of claim 1 , wherein the energy source comprises a spring.

6. The hazardous agent injection system of claim 1 , wherein the energy source is configured to eject the methotrexate from the injection outlet member in less than about 5 seconds.

7. The hazardous agent injection system of claim 1 , wherein the powered injector further comprises an outer housing member.

8. The hazardous agent injection system of claim 7 , wherein the powered injector further comprises a safety member located at a proximal end of the outer housing member.

9. The hazardous agent injection system of claim 8 , wherein the safety member is removably affixed to the proximal end of the outer housing member.

10. The hazardous agent injection system of claim 9 , wherein the safety member is removably affixed to the proximal end of the outer housing by a plurality of tabs that extend through matching openings formed in the outer housing to form a press-fit between the safety member and the outer housing member.

11. The hazardous agent injection system of claim 1 , wherein the container and the injection outlet member coupled to the container comprise a syringe.

12. The hazardous agent injection system of claim 11 , wherein the powered injector further comprises a syringe sleeve, the syringe sleeve having a bore portion configured to abut an outside of a syringe wall so as to minimize movement of the syringe caused by activation of the firing mechanism.

13. A method of treating a patient having an autoimmune disease, the method comprising injecting the patient using the hazardous agent injection system of claim 1 .

14. The method of claim 13 , wherein the autoimmune disease is selected from the group consisting of rheumatoid arthritis, juvenile rheumatoid arthritis, psoriatic arthritis, systemic lupus erythematosus, steroid-resistant polymyositis or dermatomyositis, Wegener's granulomatosis, polyarteritis nodosa, and vasculitis.