Objective To observe the structure activity and time effect relations of the central stimulating effects of modafinil
for further pharmaceutical design and development and rational use of this kind of stimulant. Method Male mice served as subjects. The experiment was divided into two parts:1) comparison between the dose(60,120,240 mg/kg)and temporal features of the effects of modafinil and its two derivatives on
locomotor activity of mice;2) Observation of the stimulating effects of modafinil(120 mg/kg) given during the day or night. Result Modafinil could significantly increase the locomotor activity of mice in a dose dependent way, the effect was best observed at the concentration of 120 mg/kg.The stimulating action of modafinil was increased by chlorination,but decreased by methylation.The central stimulating effect of modafinil showed no significant circadian difference. Conclusion The central stimulating effect of modafinil shows dose and time related features. The effect tends to be enhanced by Chlorination but reduced by methylation.