CGRP Monoclonal Antibodies

What it is

First-in-class preventive therapies designed specifically for migraine. Available as Aimovig (erenumab), Ajovy (fremanezumab), Emgality (galcanezumab), and Vyepti (eptinezumab). Unlike repurposed medications (antidepressants, anticonvulsants, beta-blockers), CGRP mAbs were developed exclusively for migraine prevention.

How it works

Monoclonal antibodies targeting either the CGRP ligand (fremanezumab, galcanezumab, eptinezumab) or the CGRP receptor (erenumab). Block the CGRP pathway implicated in migraine initiation and sensitization. Administered monthly or quarterly (fremanezumab quarterly, eptinezumab IV quarterly). Onset of effect typically within 1–4 weeks.

What patients need to know

These medications were specifically designed to prevent migraine — they're the first treatments ever built for migraine from the ground up. They work by blocking a molecule called CGRP that plays a central role in triggering migraine attacks. Most people inject them at home once a month; one (Vyepti) is given as an IV infusion every three months. They don't work for everyone, but for many people they meaningfully reduce the number of migraine days per month.

Prior authorization

Almost universally require prior authorization. Standard step therapy requires 2–3 failed oral preventives (typically from different classes: one beta-blocker or calcium channel blocker, one antidepressant, one anticonvulsant) at therapeutic dose for adequate duration (≥8 weeks each). Chronic migraine indication (≥15 headache days/month, ≥8 migraine days) required for most payers. Emgality 300mg has a cluster headache indication. Vyepti (IV) often requires separate PA from SC formulations and may face additional payer restrictions. Step therapy exceptions apply for documented contraindications, prior treatment failure, or clinician attestation of medical necessity.

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