Objective: To review the pharmacology, efficacy, and safety of the calcitonin 
gene-related peptide (CGRP) inhibitor erenumab for migraine preventive therapy. 
Data Sources: A MEDLINE/PubMed search (January 2000 to January 2019) was 
conducted using the keywords erenumab-aooe, erenumab, migraine, migraine 
prophylaxis, migraine prevention, and chronic migraine. Additional articles were 
identified by hand from references. Study Selection and Data Extraction: We 
included English-language articles (excluding poster presentations) evaluating 
erenumab pharmacology, efficacy, or safety in humans for migraine prevention. 
Data Synthesis: Erenumab is a CGRP inhibitor that inhibits vasodilation in 
response to acute migraines, which decreases pain perception during the 
migraine. Erenumab efficacy and safety has only been compared with placebo, but 
its reduction in monthly migraine days (MMDs) and medication response (≥50% 
reduction in MMDs) are comparable to current recommended off-label therapies for 
migraine prevention in short-term treatment studies. Additionally, erenumab is 
associated with low adverse event burden with no difference found compared with 
placebo per published clinical trials. Relevance to Patient Care and Clinical 
Practice: Erenumab is the first medication approved in the United States for the 
prevention of migraines in adults. No head-to-head data are available, but 
existing data suggest that erenumab is at least as effective as current 
off-label products and with reduced adverse effects. Conclusion: Erenumab is an 
effective once-monthly injectable agent for migraine prevention in patients with 
chronic or episodic migraine. It is also effective for patients who have 
previously failed migraine preventive therapy. Erenumab has a favorable adverse 
effect profile, which may improve patient adherence.