Effects of Ibuprofen on the Circadian Rhythm Variation of Body Temperature and Plasma Concentration in Rats / 中国药房

ABSTRACT

OBJECTIVE:To study the effect of different administration time of ibuprofen on the changing characteristics of circadian rhythm about body temperature and plasma concentration in rats.METHODS:60 rats were given single oral administration of ibuprofen at the dose of 50 mg per kilogram at different time(2∶00,6∶00,10∶00,14∶00,18∶00,22∶00) according to a randomized block design with another 10 rats serving as blank control.The effects of ibuprofen on circadian rhythm variations of body temperature and plasma concentration in rats were observed and analyzed using chronogram and cosine method.RESULTS:The body temperature of rats prior to and after administration both showed a significant circadian rhythm,with mean declined only,yet acrophase and amplitude showed no significant differences.The best cosinor curve equation were Yt i=38.7+0.52 Cos(15??ti—86.80?) and Yt i=37.8+0.55 Cos(15??ti—117?) respectively.The plasma concentration also showed a significant circadian change in rats at the different time points of administration.The plasma concentration in light phase was higher than that in dark phase,and the best cosinor curve equation was Yt i=41.95+5.30 Cos(15??ti—272.83?).CONCLUSION:The differences of circadian rhythm were both shown about body temperature and plasma concentration in rats when ibuprofen was orally administered at the different time points.