In many people living with migraine, there is a problem with the membranes that surround and protect the brain. These membranes are called meninges and are sensitive to pain, in much the same way the membranes of the eye can be irritated by dust or chemicals. This makes our eyes itch and become inflamed, a natural healing response.
In a migraine attack there is activation of pain reflexes in the nerves supplying the meninges. The nerve most affected is the trigeminal nerve which responds by releasing pain- and inflammation-causing chemicals. This inflammation results from changes in the blood vessels in the brain, making them relax (the more accurate term is dilate).
In the healing process, inflammation allows our immune system to fix a cut, or fight a bug. In migraine however this inflammation is not helpful, it causes redness, heat, swelling and pain, caused by certain proteins and chemicals leaving the bloodstream and surrounding the nerves.
As a consequence, the trigeminal nerve continues to sense pain even after the initial migraine trigger has passed; this inflammation can persist into a long-standing or chronic state. As a consequence, the trigeminal nerve continues to sense pain even after the initial migraine trigger has passed; this inflammation can persist into a long-standing or chronic state. This is believed to cause increased sensitivity to pain and making further migraine attacks more likely to happen ie chronic migraine, or difficult to manage migraine.
Rimegepant reduces or blocks the production of one of the chemicals called calcitonin gene-related peptide (CGRP) that acts on the blood vessels to cause inflammation in the coverings of the brain. CGRP receptor antagonists, which include drugs like rimegepant, work to stop the binding of CGRP preventing inflammation. With less inflammation in the arteries and in the brain there is less redness, heat, and swelling. This can reduce the level of pain that a patient experiences. This in turn helps to relieve migraine symptoms once a migraine starts to appear. This is why Rimegepant is also known as a CGRP antagonist.