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# Migraines
- URL: https://balaustine.mymagic.page/migraines/
- Published: 2018-06-14T23:25:20.000Z
- Updated: 2018-06-14T23:25:20.000Z
- Author: VM
- Tags: Uncategorized, #Migrated-1787483357778, #wp, #wp-post, #Import 2026-08-23 11:09

I've had migraines since 2006, when I started college. The pain is excruciating, disabling, ruinous, usually on both sides of my head. I can sense a migraine coming 12-24 hours beforehand, in the form of a small sphere of ache embedded deep inside my brain that I can amplify if I shake my head once or twice vigorously. The onset is also accompanied by constipation and a growing throbbing pain, as if a part of my brain was swollen and pushing against blood vessels flowing on the inside of the skull. When the ache kicks in fully, I can feel my heart beat in my head.

There's two ways the pain goes away – a heavy dose of paracetamol (500 mg) or by avoiding triggers. Only the latter is 100% effective, and it took me half a decade to figure out what *some of* the triggers were.

Although it's recognised to be the most common form of disability worldwide, afflicting an est. one billion people, scientists don't know what causes a migraine. It's commonly believed that it's a mix of environmental and genetic factors, with one twins [study from 2007](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2779399/pdf/10194%5F2007%5FArticle%5F427.pdf?ref=balaustine.mymagic.page) suggesting the latter's influence ranges from 34% to 51%. However, this hasn't prevented researchers from developing medicines to fight it (in much the same way we don't know how selective serotonin re-uptake inhibitors work but they're widely prescribed to treat depression).

One [study from 2006](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2751866/?ref=balaustine.mymagic.page) noted that there are two prevailing theories about the genesis of migraines united by a common theme: "the generally accepted role of the trigeminal ganglion in the painful phase of migraine". It is this commonality that a [new class](https://www.bmj.com/content/361/bmj.k2507.full?ref=balaustine.mymagic.page) of drugs called [CGRPR antagonists](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2751866/?ref=balaustine.mymagic.page) – including erenumab, galcanezumb and eptinezumab – appears to address. Their mechanism of action throws some light on our understanding of this debilitating syndrome.

The acronym stands for calcitonin gene-related peptide receptor. Calcitonin is a hormone secreted by cells in the thyroid gland; it is responsible for reducing calcium and phosphorous levels in the blood when they rise above a threshold. The peptide in question is involved in the transmission of nociception – an ["intense chemical, mechanical or thermal stimulation of the sensory nerve cells"](https://en.wikipedia.org/wiki/Nociception?ref=balaustine.mymagic.page), carried by sensory cells called nociceptors to the brain.

According to one [2008 paper](https://www.nature.com/scientificamerican/journal/v299/n2/full/scientificamerican0808-56.html?ref=balaustine.mymagic.page), a migraine could be the result of nociceptors in the brain stem (connected to the trigeminal ganglion by a single sensory root) becoming over-sensitised, with the CGRP [involved in maintaining them](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3138175/?ref=balaustine.mymagic.page) in that state. Conversely, the CGRPR antagonists work against this state.

Erenumab was developed by Amgen and is being marketed under the name Aimovig. It was [approved for use](https://www.medscape.com/viewarticle/896851?ref=balaustine.mymagic.page) by adults by the FDA on May 17, 2018, following a [phase III clinical trial](https://www.nejm.org/doi/full/10.1056/NEJMoa1705848?ref=balaustine.mymagic.page) involving 955 subjects over six months. It is to be administered as a subcutaneous injection once a month, of dose 70mg or 140 mg.

According to the trial paper, [published in November 2017](https://www.nejm.org/doi/full/10.1056/NEJMoa1705848?ref=balaustine.mymagic.page), "A 50% or greater reduction in the mean number of migraine days per month was achieved for 43.3% of patients in the 70-mg erenumab group and 50.0% of patients in the 140-mg erenumab group, as compared with 26.6% in the placebo group." But this is not entirely good news because one year's worth of injections costs $6,900, which translates to Rs 39,000 per month.

Phase III trials for galcanezumab have been completed and Eli Lilly & Co., its maker, is [awaiting FDA approval](https://en.wikipedia.org/wiki/Galcanezumab?ref=balaustine.mymagic.page). Alder's eptinezumab [entered phase III trials](http://www.alderbio.com/therapeutics/pipeline/?ref=balaustine.mymagic.page) in August 2017.