Technically, that should be SomnambutolTM, which is how it inevitably appears when mentioned – even when a character says it name in dialogue (I always wondered if they actually said the TM’s or not – Mr Chaykin, if you’re reading, please let us know :)).
A recreational barbituate and hallucinogen, SomnambutolTM, is sold in pill form by the Plex, and is soluble in most common drinks. It does not seem to have much of a taste when in drinks, so it’s presumably a popular date-rape drug in the Chicago of the 2030’s.
It is also available in a more concentrated aerosolised form, in which it is commonly used by law enforcement and private security agencies for crowd control, since it knocks people out for about an hour, and does so quickly and mostly harmlessly – although use does seem to lead to slight hangover-like symptoms afterwards.
Related drugs: Mañanacillan.