Behavioral effects of modafinil in marmoset monkeys

Rationale: Modafinil is increasingly used in sleep disturbances in general and in neurodegenerative diseases and is recently being used in healthy people for attention control. However, the application of modafinil is possibly not only restricted to alertness enhancing effects. More insight in this compound may lead to new applications. Not all behavioral aspects have been studied sufficiently; therefore, more detailed investigations on modafinil's positive and aversive behavioral effects are addressed in this paper. Objectives: Determination of effects of modafinil in marmoset monkeys with observational methods and with behavioral tests measuring locomotor activity, hand-eye coordination, response to a threat situation and startle response. Materials and methods: Two hours after oral administration of modafinil in doses of 50, 100, 150, and 225 mg/kg, animals were observed and tested in the behavioral test systems. Results: Locomotor activity was increased after 100 mg/kg modafinil in the Bungalow test and after 100, 150, and 225 mg/kg, as found in the movement parameters of the human threat test. Moreover, modafinil showed anxiolytic-like effects in the human threat test. No other side effects were observed, nor were the hand-eye coordination and startle response affected. Conclusions: Besides psychostimulation, modafinil has no aversive effects in the doses used in the domains measured. The potential anxiolytic-like effects of modafinil may create new possibilities for the therapeutic use of modafinil.