TFA doesn't explain why changing the propellant chemical means that the active medical ingredient has to change as well. Why can't epinephrine be delivered via a non-CFC propellant?

I think you misunderstood what I meant - I was implying using a series of two capacitors charged to a total of 4.2V - rather than one or two capacitors in parallel charged to 2.1V (2.1V is the maximum charge of the capacitor); this would be for cases where 2.1V is an insufficient operating voltage. So the voltage doubles as the capacitance drops in half, doubling the total energy.