Modafinil is a crystalline powder that is white to off-white in color and virtually insoluble in water and cyclohexane. It is just mildly to moderately soluble in methanol and acetone. The inactive ingredients in Modafinil tablets are croscarmellose sodium, lactose monohydrate, magnesium stearate, microcrystalline cellulose, povidone, and pregelatinized starch. Each tablet of Modafinil contains 100 mg or 200 mg of modafinil.