I've put autoinjectors in my lifesaver belt for years despite not really ever using them. In most aspects they are less valuable than simply using pill bottles, because while they are a little faster to use than toggling your belt and taking pills out of bottles with one click (since pills need the patient to stand still for a second or so) they have considerably less medicine in them, and taking them out to use them messes up the order you put them in. Auto injectors are still capable of OD'ing or addicting your patient, so while you'd like to run in jamming injectors down everyone's throats a second after they take damage, in reality you still need to double check their blood stream.
I have a few suggestions to make autoinjectors more usable and make them a somewhat viable alternative to just taking a single pill out of a pill bottle in your belt. My first suggestion would be that all autoinjectors on inject run a short check to see if the amount of medicine in the injector would cause an overdose in the patient's bloodstream. With the amount of unneccesary legacy code we've been running I don't think a brief local check on auto injector use would too hardly strain the system, as it's only needed to run the check on the tick the injector injects. If the amount of medicine in the autoinjector would cause an OD, it spits out a brief line saying something to the effect of "autoinjector safeties activated" and the injector simply won't work. This would allow medics to quickly bap people in a crowd of people hit by a grenade or something without having to worry if they just damned their patient to a painful death. First responder autoinjectors, firstaid/painstop injectors, and research injectors should probably not be able to bypass the safeties for obvious reasons.
My second suggestion ties into the first, to give a bypass to these safeties. It would require using an autoinjector on harm intent, and upon successfully bypassing the OD safety on inject, it would spit out a line saying, "Warning: Autoinjector safeties bypass, dangerous levels of medicine administered" Doing so should probably send a notification to admins as this wouldn't have a lot of legitimate use outside of bicard ODs or emergency applications, but doing so would make it incredibly easy and obvious to admins if a griffon tried to do this.
My third and final suggestion would be a small animation that plays over the head of the medic and patient, like how we do now with most medic/engi stuff, it should be unique so all the medics nearby know to not double dip the patient with a pill afterwards.