Hazardous agent injection system

1. A hazardous agent injection system, the hazardous agent injection system comprising:

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

a needle-assisted jet injector, the needle-assisted jet injector comprising:

a container configured to contain the methotrexate;

an injection outlet member associated with the container, the injection outlet member including an injection-assisting needle configured to pierce the skin of a patient and deliver a jet of methotrexate to the patient subcutaneously;

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

an energy source associated with the firing mechanism and configured to power the firing mechanism and to jet inject the methotrexate from the injection outlet member as a fluid jet; and

a trigger mechanism associated with the firing mechanism and configured to activate the firing mechanism,

wherein the needle-assisted jet 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 a patient following administration of a dose of the methotrexate to the patient (“C max ”) with the hazardous agent injection system, (b) the time to reach the maximum concentration of methotrexate in blood plasma of a patient following administration of a dose of the methotrexate to the patient with the hazardous agent injection system (“T max ”) and (c) area under the curve of the concentration of methotrexate in blood plasma of a patient following administration of a dose of the methotrexate to the patient with the hazardous agent injection system of the needle-assisted jet injected methotrexate (“AUC”) falls between about 80% and about 125% of a corresponding measured confidence interval of the same dose of methotrexate delivered subcutaneously or intramuscularly by a hand-powered syringe, and wherein the needle-assisted jet injector is configured to subcutaneously inject the methotrexate at a pressure of at least 80 psi.

2. The jet injector of claim 1 , wherein the amount of methotrexate is therapeutically effective to treat an inflammatory disease.

3. The jet injector of claim 2 , wherein the inflammatory disease is rheumatoid arthritis.

4. The jet injector of claim 1 , wherein the container is received within the jet injector for expelling the methotrexate.

5. The jet injector of claim 1 , wherein the gauge of the needle is selected from 26 gauge and a higher gauge number.

6. The jet injector of claim 5 , wherein the gauge of the needle is selected from 26 gauge, 27 gauge and 28 gauge.

7. The jet injector of claim 1 , wherein the jet injector is configured to inject the methotrexate such that the methotrexate is jet injected at a flow rate of at least about 0.5 ml/sec.

8. The injection system of claim 1 , wherein the gauge of the injection-assisting needle is selected from 26 gauge, 27 gauge and 28 gauge, and the methotrexate is jet injected at a flow rate of from 0.5 ml/sec-1.0 ml/sec.

9. A method of treating a patient having an autoimmune disease, the method comprising administering methotrexate to the patient using the jet injector of claim 1 .

10. The method of claim 9 , 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.