FIG. 1 is a front elevational view of a medication injection device showing our new design; FIG. 2 is a rear elevational view thereof; FIG. 3 is a side elevational view thereof from the left of FIG. 1; FIG. 4 is a side elevational view thereof from the right of FIG. 1; FIG. 5 is a top plan view thereof; FIG. 6 is a bottom plan view thereof; and, FIG. 7 is a front, bottom and side perspective view thereof.