Reason for the aggravation of diseases caused by inflammation and the ineffectiveness of NSAIDs on these diseases in rainy weather.

In this study, the anti-inflammatory activity of indomethacin, diclofenac, meloxicam and nimesulide were investigated on sunny and rainy days. Parallel to these experiments, the question of whether endogenous adrenaline and cortisol (corticosterone in rats) are factors that affect medicinal activity of these anti-inflammatory drugs on sunny and rainy days was examined. Our experimental results show that the drugs used produced significant anti-inflammatory effects on sunny days (76.5, 62.8, 56.9 and 64.7%, respectively) but were less effective on rainy days. On sunny days, adrenaline levels decreased by 83-86% in the groups that received indomethacin, diclofenac, meloxicam or nimesulide, compared to the control group. In contrast, there was no significant difference in corticosterone levels in any of these groups. In addition, the adrenaline and corticosterone levels of intact (versus adrenalectomized) rats decreased by 83% and 58.8%, respectively, on rainy days compared to sunny days. Indomethacin, diclofenac, meloxicam and nimesulide were found to exert anti-inflammatory effects by decreasing adrenaline levels but not affecting corticosterone levels. The anti-inflammatory effects of the tested drugs was eliminated on rainy days due to the low level of corticosterone.