The anti-inflammatory effect of nimesulide is due to the inhibition of cyclooxygenase-2 (COX-2), an enzyme involved in prostaglandin synthesis via the arachidonic acid pathway. This results in decreased levels of prostaglandins that mediate pain, fever, and inflammation.
Nimesulide is rapidly absorbed after oral administration. Nimesulide has a relatively rapid onset of action, with significant reductions in pain and inflammation observed within 15 minutes of drug ingestion. Plasma protein binding is greater than 97%. Nimesulide undergoes extensive biotransformation, primarily to 4-hydroxynimesulide. 4-Hydroxynimesulide is also biologically active. Elimination is largely renal and to a lesser extent fecal. The half-life of nimesulide is 2-4 hours.