Ibuprofen - Mechanism of Action

Mechanism of Action

Nonsteroidal anti-inflammatory drugs such as ibuprofen work by inhibiting the enzyme cyclooxygenase (COX), which converts arachidonic acid to prostaglandin H₂ (PGH₂). PGH₂, in turn, is converted by other enzymes to several other prostaglandins (which are mediators of pain, inflammation, and fever) and to thromboxane A₂ (which stimulates platelet aggregation, leading to the formation of blood clots).

Like aspirin and indomethacin, ibuprofen is a nonselective COX inhibitor, in that it inhibits two isoforms of cyclooxygenase, COX-1 and COX-2. The analgesic, antipyretic, and anti-inflammatory activity of NSAIDs appears to operate mainly through inhibition of COX-2, whereas inhibition of COX-1 would be responsible for unwanted effects on the gastrointestinal tract. However, the role of the individual COX isoforms in the analgesic, anti-inflammatory, and gastric damage effects of NSAIDs is uncertain and different compounds cause different degrees of analgesia and gastric damage.

To achieve the beneficial effects of ibuprofen and other NSAIDs without gastrointestinal ulceration and bleeding, selective COX-2 inhibitors were developed to inhibit the COX-2 isoform without inhibition of COX-1.