Epinephrine is a hormone and neurotransmitter that, among other functions, increases breathing and heart rate, inhibits insulin, and increases blood sugar levels. It is also known as adrenalin/adrenaline. The two names it goes by are etymologically the same, just from two different languages. Epinephrine is secreted by the glands which sit on top of the kidneys, known as the adrenal glands. From this the Latin name, adrenaline, is derived. ‘Adrenal’ comes from the Latin ad (on) + ren (kidney). In Greek, this is epi (above) + nephros (kidney): epinephrine. The adrenal glands are also sometimes called the suprarenal glands (supra is Latin for ‘above’), which is why at one point this hormone also went by ‘suprarenalin’ and ‘suprarenin’ (‘adrenin’ also competed with ‘adrenaline’ for a while).
Epinephrine is the favored term in Japan, Canada, the US, and Spain. It is also the primary term used by the WHO’s International Non-propietary Names list. Adrenaline is generally used elsewhere (funny enough, this includes Greece). According to Jeffrey K. Aronson, there are strong reasons to favor the use of ‘adrenaline’ over ‘epinephrine’:
- Safety: epinephrine can be easily mistaken in hospitals for ephedrine, whereas there is no such problem with adrenaline.
- Consistency: the glands which produce the hormone are called the adrenal glands, not the epinephric glands. ‘Adrenal’ glands is also more commonly used than ‘suprarenal’ glands. The term ‘epinephrin’ was first used by John Abel on the suggestion by Josef Hyrtl that the adrenal glands be called ‘epinephris’ (although Abel himself called them the suprarenal capsules), which has clearly not been taken up.
- History: John Abel chose ‘epinephrin’ to describe his extract from the adrenal glands. However, he had only extracted an inactive form of the hormone. The first pure extract was done later by Jokichi Takamine, who patented his extract as adrenaline.
Since choice of words is done subordinate to the end of clear communication, I would say the first of these is strongest. The historical argument is weakest, since it relies on a principle that someone who isolated an inactive form of a compound should not get the honor of naming it.
EDIT: I also forgot that another argument that Aronson mentions is that ‘adrenaline’ is the colloquial term for the substance that causes excitement (e.g., ‘adrenaline rush’ is commonly used whereas nobody says ‘epinephrine rush’). This does have a benefit of making medical terminology more transparent to patients.