I think it is the opposite for something ready to be administered. Sure, a certain mass of the active ingredient is suspended in a specific volume of an inactive medium like saline. But when a physician is ready to administer it, it is much easier to portion out the desired volume of medicine than to weigh it out. As long as the mixture has an established ratio of active ingredient to inactive medium, measuring out the desired volume should be quick and effective.
It could be that the inaprovaline hypospray they use has a ratio of 1mg per 1cc, and that everyone knows that. Meaning that one could say either "20 mg" or "20 cc" and they would be asking for the exact same quantity of the active ingredient.
One year later and he’s casually jumping back to the 1960s just to kinda, y’know, see what was up?
The intro of that episode just casually mentioning that they voluntarily went back in time as if it was just some common routine was rather jarring to me. Until then, time travel occurring in Star Trek had always been some kind of unintentional anomaly.
I recognize most of those as things from early TOS episodes that were contradicted even in later TOS episodes. Is that "thousands of light years" thing also an example of that?
It does seem like it was entirely written and shot as a TV series, and was only reworked as a feature length film during editing.