Adrafinil is a mild central nervous system stimulant drug used to relieve excessive sleepiness and inattention in elderly patients. It is also used off-label by individuals wishing to avoid fatigue, such as night workers or others who need to stay awake and alert for long periods of time.

Adrafinil is a prodrug; it is primarily metabolized in vivo to modafinil (Provigil), resulting in nearly identical pharmacological effects. Unlike modafinil, however, it takes time for the metabolite to accumulate to active levels in the bloodstream. Effects usually are apparent within 45-60 minutes when taken orally on an empty stomach.

Adrafinil, also known by the codename CRL 40028, has as its chemical name 2-(Diphenylmethyl) sulfinyl acetohydroxamic acid. Its molecular formula is C15H15NO3S. The drug's molecular weight is 289.4 daltons.

Adrafinil does not currently have FDA approval in the United States, although it is used in France and elsewhere in Europe. The drug is marketed by the USAn pharmaceutical company Cephalon, which acquired Group Lafon in 2001, under the brand name Olmifon.