In the human body, a headache is signalized by so-called prostaglandins. Prostaglandins are locally acting messenger molecules. They are mediators and have a variety of strong physiological effects, such as regulating the contraction and relaxation of smooth muscle tissue. Moreover, they sensitize nerve endings that transmit pain signals to the brain.
Prostaglandin is generated by the enzyme cyclooxygenase (COX). Pharmacological inhibition of COX-2 can provide relief from the symptoms of inflammation and pain, since the prostaglandin synthesis is prevented and no pain signals can be transmitted to the brain.
The area in the COX-2 enzyme, where prostaglandins are produced, is called the binding pocket of the enzyme. It is the center of the enzym's activity and you can compare it to a lock, where only a suitable key, namely the drug molecule, can fit.
On the next page you can learn more about drugs to treat headaches.