What is CGRP?

Calcitonin Gene Related Peptide is an important chemical neurotransmitter involved in the transmission of pain signals through the nervous system and associated with the triggering of migraine attacks. It was discovered in 1984 and has been extensively studied since. It is a type of protein produced in various tissues in the body and, when it builds up in the nervous system, it triggers receptors which initiate pain pathways and start the migraine attack.

What are anti-CGRP drugs?

These are drugs which stop the action of CGRP. They may be used either as migraine preventers or for acute attacks depending on the type of medication. This factsheet is about the preventers.

The new anti-CGRP medications for prevention of migraine:

Monoclonal antibody medications -the Mabs

How do they work?

There are some new drugs called Monoclonal antibodies (Mabs) which work on the pain pathway that CGRP is involved in. Monoclonal antibodies are man-made proteins that act like human antibodies by attaching themselves to target proteins and enhancing the body’s immune system to attack and destroy the target proteins.

One of these binds to the receptor (Erenumab/Aimovig); the others bind to the ligand, the protein itself (Fremanezumab/Ajovy; Galcanezumab/Emgality; Eptinezumab/Vyepti).

They have been studied over the last few years to see how safe and effective they are and they have all recently been approved by the FDA in the USA for use in migraine. Some of them are now approved or awaiting approval in Europe and the UK. (See later)

Who are they suitable for?

They may be useful to anyone with episodic or chronic migraine, with or without aura with certain exceptions. They cannot be used in pregnancy and the recommendation is to stop them 6 months before trying to conceive. They are not licensed in children. Only one of them (Galcanezumab/Emgality) has been studied in people with migraine aged over 65. There are no restrictions in terms of other conditions apart from co-existing active heart disease.

What are the side effects?

The commonest reported side effects are constipation, stinging at the site of injection and upper respiratory tract infections have been reported by some.

Do they work for everyone?

No. Unfortunately no migraine treatments currently available work for everyone. They work in about 50- 60% of people who try them. In some cases, the improvement is dramatic but in others, it is not as effective but can reduce the severity and frequency of the migraines enough to make a difference on their impact on daily life. There are some people who do not respond to these at all.

How quickly do they work?

If the Mabs are going to help, they often start to work more quickly than other preventatives and may improve things even in the first month. We recommend trying an initial course of three months before judging efficacy.

How long should they be taken?

The recommendation is to stay on them for a year and then review whether to continue or stop. The decision will be made by discussion with the Headache Specialist and the patient.

What if one does not work?

It is possible to change to one of the other Mabs. If one is just not working, it is possible to switch straight over to an alternative. If there have been side effects, the manufacturers advise a washout period of 3-6 months before trying a different one.

Anti-CGRP injections via the National Migraine Centre

As we are a charity and these are expensive medications, we do charge for the consultation for these. The current costs are as follows:
Initial Consultation: £200
Follow Up consultation: £100

The cost of the injections are paid directly to the pharmacy and not the National Migraine Centre.  The cost for the injections are:

AIMOVIG: 

Price per injection: £386.50

Offer: 3 injections for the price of 2 (so the cost per injection is therefore £257.67)

AJOVY:

Price per injection: £385

Offer: For the first 3 months the cost per injection is £224.90 and afterwards the cost per injection is £299.

EMGALITY:

Price per injection: £386.50

Offer: 3 injections for the price of 2 (so the cost per injection is therefore £257.67)

Anti-CGRP medication on the NHS

In Scotland both Aimovig and Ajovy have been approved for use under certain circumstances and individual Health boards in Scotland have interpreted the guidelines differently.

In the rest of the UK, Aimovig was initially not approved by NICE but an appeal is pending.

Ajovy has been approved for use in Chronic Migraine sufferers who have tried and failed three other preventers. It cannot be prescribed by GPs. It must be prescribed by a Headache Specialist Clinic. This was due to be implemented on April 15th 2020 but the COVID19 pandemic has resulted in a delay and we have no information about when this will be implemented now. There are likely to be long delays in getting an appointment in Specialist NHS Headache clinics even when this is finally approved and implemented.

 

This information is provided as a general guide only and is not a comprehensive overview of prescribing information. If you have any queries or concerns about your headaches or medications please discuss them with your GP or the doctor you see at the National Migraine Centre.