A Neural paralyzer is a central nervous system depressant, standard in Starfleet medkits circa 2260. Used in surgery as a preanesthetic, it acts within 5-10 minutes and lasts for about 15-20 minutes to depress cardiac and respiratory functions, incidentally making the subject nearly appear dead. (TOS: "Amok Time")

There may be many such available drugs of this type, one of which might be melenex.