03.01.3.2 Inhibitioin of Cyclooxygenase

For instance, cyclooxygenase is an enzyme involved in pain and fever, and the cyclooxygenase inhibitor paracetamol is used in the treatment of pain and fever. Normally, we have low levels of free arachidonic acid as it is mostly stored as a component of the cell membrane (Figure 3.10).

Figure 3.10 Activation of cyclooxygenase (Copyright QUT, Sheila Doggrell)

Many stimuli, including bacterial infection can reverse this to cause the release of arachidonic acid (Figure 3.10). Once released, arachidonic acid is readily metabolised to prostaglandins, in the presence of the widespread enzyme cyclooxygenase. The prostaglandins are mediators of pain and fever.

Paracetamol is a cyclooxygenase inhibitor (Figure 3.11).

Figure 3.11 Mechanism of action of paracetamol

Inhibition of the enzyme cyclooxygenase with paracetamol leads to reduced levels of prostaglandins, and consequently of the pain and fever mediated by prostaglandins.