Time varying variable within ODE function

I have a variable that is used within my ODE45 function; however, it is a function of time. I discovered that I can't use the time variable within my ODE function because it is just the time step that ODE45 is using during the current call, not the total time like I need.

The only way I can think to solve this problem is to put my ODE45 in a FOR loop and discretize the variable.

Is there any other way to change a variable within my ODE function?