Calcitonin Gene-Related Peptide Blocker

Aka: Calcitonin Gene-Related Peptide Blocker, CGRP Antagonist, Injectable Calcitonin Gene-Related Peptide Blocker, Injectable CGRP Inhibitor, Erenumab, Ajovy, Fremanezumab, Emgality, Galcanezumab, Aimovig

1. See Also
   1. Gepant (Oral CGRP Inhibitor)
   2. Migraine Prophylaxis
2. Indications
   1. Migraine Prophylaxis if refractory to first-line agents
3. Mechanism
   1. CGRP Antagonists block CGRP activity (vasodilator)
   2. CalcitoninGene-Related Peptide (CGRP) levels increases at Migraine Headache onset
      1. Vasodilator
      2. Pain sensitizer
4. Preparations
   1. Erenumab (Aimovig) autoinjector
      1. Inject SQ once monthly in Abdomen, thigh, upper arm
   2. Ajovy (Fremanezumab)
      1. Three injections from prefilled syringes once every 3 months
   3. Emgality (Galcanezumab)
      1. Once monthly injection via pen
5. Adverse Effects
   1. Injection site mild reactions
   2. New onset or worsening Hypertension (Erenumab or Aimovig)
      1. Associated with 60 cases of systolic increase of 40 mmHg, diastolic increase of 30 mmHg
      2. Occurred within 1 week of first or second dose
      3. May be related to the blockade of CGRP which is a vasodilator
      4. Avoid in Uncontrolled Hypertension or significant cardiovascular risk
      5. Incorporate Home Blood Pressure Monitoring for the first few months after starting
      6. (2021) Presc Lett 28(4): 19-20
      7. Saely (2021) Headache 61(1):202-8 [PubMed]
6. Efficacy
   1. Reduces migraine Incidence by 2 fewer Migraine days/month
7. Disadvantages
   1. Limited safety data outside healthy patients without comorbidity at time of 2018 release
   2. Expensive: $6900 per year
8. References
   1. (2018) Presc Lett 25(8)
   2. (2018) Presc Lett 25(12): 70