Ask the Pharmacist

Q) I have heard there is a new medication designed to prevent migraines. What can you tell me about it and how does it compare to existing treatments?

A) While Health Canada has undoubtedly been spending much of its resources assessing the safety and effectiveness of the new COVID-19 vaccines just hitting the market, it has also found the time to approve a few other drugs as well.

One of these drugs is Ajovy (fremanezumab), an injectable drug intended to prevent migraines. It is the third member from a class of drugs known as the calcitonin gene-related peptide (CGRP) inhibitors. It joins its predecessors Aimovig (erenumab) and Emgality (galcanezumab).

This class of drugs was first introduced to Canada in the summer of 2018 and have been literally life changers for some of the people who have been prescribed them. They work by interfering with the actions of CGRP, a protein that inflames the endings of nerves and is intimately involved in the development of migraines (note, there is now proof that Emgality also helps prevent cluster headaches which are a series of super intense headaches that last up to 3 hours and can recur repeatedly over a 24 period, sometimes continuing for a few weeks at a time).

They are all given by a subcutaneous injection which can be easily done by a patient at home, much like insulin. The good news is that you don’t have to “poke” yourself daily like a diabetic has to. They are generally administered once per month, although this newest member, Ajovy, can be administered once every 3 months as a series of 3 consecutive injections on the same day. This class of drugs seems to work very well, perhaps befitting the fact that they are the first drugs designed to specifically prevent migraines.

Previously, all of the other drugs that we use for this purpose were originally designed to treat conditions like high blood pressure, seizures, depression and others. Studies show that patients taking the CGRP inhibotors experience about 50% fewer migraine days per month, on average this means about an additional 1-2 migraine free days a month. That may not seem like much to some of us, but for most of my migraine patients that is an extra 2-4 weeks a year they can live, work and enjoy life (well, at least when COVID goes away) rather than lying in bed in a darkened room trying not to vomit.

That being said, this sort of success rate is about equal to that of the more traditional pill types that have been repurposed for this indication such as topiramate, valproic, metoprolol and amitriptyline among others.

Side effects with the CGRP’s are generally mild and compare very favourably to those of the oral options. The most common one noted is what you would expect from a needle, namely pain, redness or itchiness at the injection site. Other common effects include constipation (3-4% of people complain about this) and muscle cramps or spasms. They also do not have any known interactions with other drugs. This is all very positive, but as with everything, there are downsides.

First off, these drugs have not been around very long so we are still not sure if there will be any long-term safety risks with them. The data looks promising thus far, but these are still the early days. Since the protein CGRP is found throughout our body, and is involved with dilating (i.e. widening) our blood vessels, there are theoretical concerns about whether these drugs could put one at risk of cardiovascular disorders such as a stroke.

Secondly, the CGRP’s are not cheap, a regrettable reality for just about every new drug these days. Ajovy will cost about $620 per month as compared to about $670 for Emgality and $580 for Aimovig. This is many times the costs of their oral rivals which frequently cost under $50 a month.

As well, none of the CGRP’s are usually covered by the provincial health plan and many private insurers are either not paying for them or are requiring patient’s to get special authorization before the insurance company will pick up the tab (this is a process in which paperwork is sent to the prescribing doctor asking him/ her to make a case as to why the drug should be covered and usually means you must have previously tried at least a few of the existing less expensive options).

The manufacturers of the CGRP’s may provide ongoing financial help or even pay the full cost of these treatments until such time as your insurance company/ government health plan has had time to assess your situation. These can be accessed via the internet or your pharmacy/doctor can help you make the connection.

Regardless, whether you are paying for it or not, the CGRP’s are expensive and still relative “newbies” which is why it is suggested that they be reserved for patients who have failed several other tablet type therapies either due to side effects or a lack of effectiveness. It is also suggested that only those patients who experience 4 or more migraines a month (or 8 or more headache days depending upon how long your migraines last for) be prescribed this class.

As to the differences between the three members, besides price, there is not really very much to say. All are stored in the refrigerator but there are differences as to how long they can remain stable at room temperature. As well, the manner in which they are injected can differ (Ajovy is a prefilled syringe, Aimovig is an auto-injector & Emgality comes in both forms).

While there are as of yet, no great head-to-head comparisons between the three drugs, they do seem to be equally effective with very similar side effect profiles. If one of the agents does not work, it is reasonable to try a different member although only about 1 in 3 people who do this find the new CGRP works better than the previous one.

The CGRP’s look like they can be combined with the oral options safely but it is still too early to tell if the combination works better than either drug alone. While it’s always nice to have a new option, Ajovy looks more like yet another “me too” type drug rather than presenting a true breakthrough in migraine prevention type therapy. For more information about this or any other health related questions, contact you pharmacist.