Mechanism of action of diclofenac sodiumdiclofenac possess analgesic, anti-inflammatory and antipyretic action. it inhibits the enzyme cyclo-oxygenase and there by inhibits the synthesis of prostaglandins (pgs). it is more potent against cyclo-oxygenase-2 enzyme as compared to other nsaids like indomethacin, naproxen etc. it reduces intracellular concentrations of free arachidonic acid in leukocyte by altering its release or uptake. .pharmacokinets of diclofenac sodiumabsorption: diclofenac sodium is rapidly absorbed after oral administration. it undergoes first pass metabolism and its bioavailability is 50 % only. distribution: it is distributed in highly protein bound form. metabolism: diclofenac sodium is metabolised in the liver. excretion: drug and metabolites are primarily excreted in urine and some amount in the bile.