Dispensed by Cally to counter fatigue shock in Horizon: described as one third adrenalin, two thirds soma. The crew had been virtually living on it for weeks, according to Cally, yet Vila still had to ask what it was.
Adrenalin is a stimulant hormone, raising heart rate in response to sudden stress.
Soma has a number of meanings. It can refer to the cell body of a nerve cell (from the Greek *soma* the body), but the more likely connection seems to be to Hindu mythology where Soma is the moon-plant, the juice of which bestows immortality -- an intoxicating drink called soma is used in some Vedic rituals. This strongly echoes the tranquillising drink of the same name in Aldous Huxley's Brave New World. However, the derivation here may also be from the Latin *somnus* to sleep.
"Adrenalin and Soma" implies a combined stimulant/tranquilliser (Justin referred to it as a "stimulant", although it appeared to work on Vila as a relaxant in Horizon and Volcano. The names are not, perhaps, to be taken too literally. Taking large quantities of adrenalin in particular seems distinctly unwise. Adrenalin and Soma might therefore have been the trade name of a marketed product, or even a colloquial term of reference.