Spray applicator

From Memory Alpha, the free Star Trek reference

The spray applicator, circa 2260s to 2270s, was a medical device standard in medkits. It is capable of dispensing a wide variety of topical liquids, foams and gels. The spray applicator was routinely preloaded with a flesh-colored suspension of a coagulant, numbing anesthetic, and antibiotic.

It was used to treat Pavel Chekov's burns when he was injured by a sparking bridge console. (Star Trek: The Motion Picture)