About dexamethasonea potent synthetic glucocorticoid, antiasthmatic, anti-inflammatory and immunosuppressant.mechanism of action of dexamethasonethe drug exerts it`s pharmacological action by penetrating and binding to cytoplasmic receptor protein and causes a structural change in steroid receptor complex. this structural change allows it`s migration in to the nucleus and then binding to specific sites on the dna which leads to transcription of specific m-rna and which ultimately regulates protein synthesis. it exerts highly selective glucocorticoid action. it stimulates the enzymes needed to decrease the inflammatory response. the drug exerts anti-inflammatory and immunosuppressant actions as follows: - 1) induce lipocortins in macrophages, endothelium, and fibroblasts which inhibits phospholipase a2 and thus decreases the production of prostaglandins, leukotriens (lt), and platelet activating factor, 2) causes negative regulation of genes for cytokines in macrophages, endothe