Emgality (galcanezumab) works by blocking the effect of a protein, called CGRP (calcitonin gene-related peptide) which is involved in pain transmission. Emgality binds to CGRP and prevents it from interacting with the CGRP receptor.

Emgality belongs to the class of medicines called CGRP inhibitors. There are two types of CGRP inhibitors – monoclonal antibodies and CGRP receptor antagonists (gepants). Emgality is a monoclonal antibody, which is a collection of identical proteins that have been developed to only target one substance in the body (in this case CGRP). Emgality is given by injection subcutaneously (under the skin), to avoid degradation by the stomach. Because it is a large molecule, it takes longer to start working, and works in the lining of the brain rather than in the brain itself. Monoclonal antibodies tend to have few drug interactions and are unlikely to cause liver or kidney damage.

Emgality may be used in adults to prevent migraines or to treat episodic cluster headaches.

What is CGRP and how is it involved in migraine?

CGRP is a small protein that is highly prevalent in the sensory nerves that supply the head and the neck.

When CGRP is released it causes intense inflammation in the coverings of the brain (called the meninges), and for most migraine patients, causes the pain of a migraine attack. Levels of CGRP are increased during a migraine attack and CGRP may also help initiate a migraine attack.

Trials have shown that if you inject CGRP into a person without migraine, within four hours most of them will develop a migraine. It was from this research that CGRP inhibitors were developed.