Refillable autoinjectors should be added as a new item to be used by the Paramedic. They should be stored in Medical Storage.
Autoinjectors are superior to syringes for emergency medical situations. They are far faster than syringes. Syringes are useful for giving measured doses, but there is rarely enough time for careful dosing when someone is in critical condition and seconds from death. These new autoinjectors should have a different appearance than the disposable ones that currently exist. They should be fillable from bottles and administer the same dosage as the disposable autoinjectors.
I understand that autoinjectors used to be refillable in SS13 in the past (perhaps not on this server, though). They were removed because they were too effective when used by antagonists for delivering poisons. The syringe gun is even more effective at delivering poisons than an auto injector yet they remain in Medical Storage. There should be no problems with antagonists using refillable autoinjectors if they are stored in Medical Storage because they would already have access to the syringe guns at that point.
It is not clear if reusing syringes causes infections. I have tested this on myself many times during extended rounds and have never been infected. If I am wrong, then the needle assembly of the refillable autoinjector should be replaceable (grab the tip with empty hand while the autoinjector is in the other hand).