Armodafinil (brand names Nuvigil, Acronite, R-Modawake, Artvigil, Waklert) is the enantiopure of the wakefulness-promoting agent, or eugeroic, modafinil (Provigil). It consists of just the (−)-(R)-enantiomer of the racemic modafinil. Armodafinil is produced by the pharmaceutical company Cephalon Inc. and was approved by the U.S. Food and Drug Administration (FDA) in June 2007.
Although they have similar half-lives, armodafinil reaches its peak concentration in the blood later after administration than modafinil does, which may make it more effective at improving wakefulness in patients with excessive daytime sleepiness. More: en.wikipedia.org.