1. A method for reducing the rate of disease progression of ALS in a patient the method comprising administering to the patient a therapeutically effective amount of 3-methyl-1-phenyl-2-pyrazoline-5-one or a pharmaceutically acceptable salt thereof in combination with a therapeutically effective amount of a deuterated arachidonic acid or a prodrug thereof; wherein the rate of disease progression in the patient is less than the aggregate achieved by either drug; and wherein the deuterated arachidonic acid or a prodrug thereof is administered using a dosing regimen that includes a loading dose and a maintenance dose.