To the OP: Is yours a vented system? If so, can't you save the water and put
it back into the header tank so as not to lose the inhibitor? That's what I
do.

You can even if it's a sealed system.

For my secondary circuit that provides heating to my workshop, I
decided to use an inhibitor containing an anti-freeze - Fernox
Alphi-11. To achieve what I felt to be a good margin of minimum
temperature, several containers were needed and it is fairly expensive.
I therefore fitted two filling points. One is in the house and
mains water can be used in the normal way. The other is in the
workshop together with a drain point. The expansion vessel is also in
the workshop. I can isolate the garage part of the circuit from the
house with two valves.

I made up a filling gizmo consisting of a garden sprayer with several
plumbing fittings attached to the wand to adapt it to fit the filling
point. I can drain part or all of the system and collect the water.
I can then pump it back in using the sprayer. There is enough oomph
in these things than I can just about get 2 bar, so in effect I can
repressurise using the old water.

Since the sprayer is about the same cost as a dose of regular Fernox,
it may well be worth something like this during extended plumbing
operations.