injection vs injectant

injection and injectant both are nouns.

Word	Noun	Adjective	Verb	Adverb
injection	Yes	No	No	No
injectant	Yes	No	No	No

As nouns, injection and injectant are synonyms defined as:

injection and injectant: any solution that is injected (as into the skin)

injection (noun)	injectant (noun)
the forceful insertion of a substance under pressure	any solution that is injected (as into the skin)
the act of putting a liquid into the body by means of a syringe
any solution that is injected (as into the skin)