Effects of modafinil on heat thermoregulatory responses in humans at rest.
The effects of modafinil on heat thermoregulatory responses were studied in 10 male subjects submitted to a sweating test after taking 200 mg of modafinil or placebo. Sweating tests were performed in a hot climatic chamber (45 degrees C, relative humidity <15%, wind speed = 0.8 m x s(-1), duration 1.5 h). Body temperatures (rectal (Tre) and 10 skin temperatures (Tsk)), sweat rate, and metabolic heat production (M) were studied as well as heart rate (HR). Results showed that modafinil induced at the end of the sweating test higher body temperatures increases (0.50 +/- 0.04 versus 0.24 +/- 0.05 degrees C (P < 0.01) for deltaTre and 3.64 +/- 0.16 versus 3.32 +/- 0.16 degrees C (P < 0.05) for deltaTsk (mean skin temperature)) and a decrease in sweating rate throughout the heat exposure (P < 0.05) without change in M, leading to a higher body heat storage (P < 0.05). AHR was also increased, especially at the end of the sweating test (17.95 +/- 1.49 versus 12.52 +/- 1.24 beats/min (P < 0.01)). In conclusion, modafinil induced a slight hyperthermic effect during passive dry heat exposure related to a lower sweat rate, probably by its action on the central nervous system, and this could impair heat tolerance.
Launay
Jean-Claude
JC
Département des Facteurs Humains, Centre de Recherches du Service de Santé des Armées, La Tronche, France. jclaunay@crssa.net
Besnard
Yves
Y
Guinet
Angélique
A
Bessard
Germain
G
Raphel
Christian
C
Savourey
Gustave
G
D000328:Adult; D000704:Analysis of Variance; D001559:Benzhydryl Compounds / Q000494:pharmacology*; D001833:Body Temperature Regulation / Q000187:drug effects* / Q000502:physiology; D006358:Hot Temperature; D006801:Humans; D008297:Male; D000077408:Modafinil; D012146:Rest / Q000502:physiology*; D013546:Sweating / Q000187:drug effects / Q000502:physiology
D001559:Benzhydryl Compounds; D000077408:Modafinil