DRUG CLASS AND MECHANISM: Modafinil is an oral drug that is used for improving wakefulness in patients with excessive sleepiness.It is similar to armodafinil (Nuvigil). Like amphetamines, modafinil promotes wakefulness by stimulatIng the brain. The exact mechanism of action of modafinil is unknown.RUG CLASS AND MECHANISM: Modafinil is an oral drug that is used for improving wakefulness in patients with excessive sleepiness.