What injectable calcitonin gene‑related peptide (CGRP) inhibitors are available for migraine prevention?

Injectable CGRP Inhibitors for Migraine Prevention

Four injectable CGRP monoclonal antibodies are FDA-approved for migraine prevention: eptinezumab, erenumab, fremanezumab, and galcanezumab. 1

Available Injectable CGRP Monoclonal Antibodies

The injectable CGRP-targeting therapies include:

• Eptinezumab - administered as an intravenous infusion every 3 months 1
• Erenumab - subcutaneous injection targeting the CGRP receptor 2, 3
• Fremanezumab - subcutaneous injection targeting the CGRP ligand 2, 3
• Galcanezumab - subcutaneous injection targeting the CGRP ligand 2, 3

Efficacy and Clinical Performance

These injectable CGRP monoclonal antibodies demonstrate substantial efficacy with evidence vastly exceeding that of traditional first-line preventive treatments. 2

Response Rates and Timeline

• The ≥50% responder rates progressively improve over time: 45.9% at 3 months, 57.0% at 6 months, 63.6% at 12 months, and 71.0% at 24 months 4
• Monthly fremanezumab 225 mg showed the most robust efficacy in reducing monthly migraine days and achieving 50% response rates 5
• Monthly erenumab 140 mg was optimal for reducing acute medication usage days 5
• Significant reductions in monthly migraine days are sustained across 24 months of treatment 4

Response Patterns

• Early responders (≥50% reduction by month 3) had the lowest baseline migraine burden 4
• Late responders (months 4-5) and ultralate responders (after month 6) had higher baseline monthly migraine days, higher disability scores, and more prior preventive treatment failures 4
• Nonresponders typically had the highest baseline migraine frequency, highest disability scores, and highest rates of medication overuse headache and psychiatric comorbidities 4

Safety and Tolerability Profile

Injectable CGRP monoclonal antibodies demonstrate favorable safety profiles with generally mild adverse events occurring in only 12.6% of patients. 4

• Adverse events are typically mild, including injection site reactions, constipation, and muscle cramps 1
• Serious adverse events are rare 2
• Treatment discontinuation due to adverse events is not significantly different from placebo 5
• No black box warnings are associated with these medications (unlike some traditional preventive agents like topiramate) 1

Treatment Persistence

• Continuation rates were 68.3% at 12 months, 58.0% at 18 months, and 50.6% at 24 months 4
• These persistence rates reflect real-world adherence patterns and are substantially better than traditional oral preventive medications 4

Cost Considerations

The primary limitation of injectable CGRP monoclonal antibodies is cost, with median annual treatment costs ranging from $7,071 to $22,790. 1

• These medications are not available as generic formulations 1
• Cost-effectiveness analyses with low certainty suggest erenumab and fremanezumab may have intermediate value compared to no preventive treatment in patients with at least one previous treatment failure 1
• Eptinezumab requires additional costs for outpatient intravenous infusion administration every 3 months 1

Clinical Positioning

The American Headache Society position statement designates CGRP-targeting therapies as first-line options for migraine prevention without requiring prior failure of other preventive treatment classes. 2

However, the American College of Physicians 2025 guideline recommends prioritizing less costly alternatives (metoprolol, propranolol, valproate, venlafaxine, amitriptyline) as initial treatments due to lack of appreciable differences in efficacy but substantial cost differences 1. This reflects the reality that while CGRP monoclonal antibodies have equal or superior efficacy and tolerability compared to traditional first-line agents, economic factors influence guideline recommendations in the absence of clear superiority in mortality or morbidity outcomes 1.

Patient Preference Considerations

• Patients probably prefer oral treatments over injectable therapies (moderate-certainty evidence) 1
• When cost is not a limiting factor, patients prefer CGRP monoclonal antibodies; when cost matters, less expensive alternatives are preferred 1
• Route of administration is probably as important to patients as the effect on migraine frequency 1

Common Pitfalls to Avoid

• Do not discontinue treatment prematurely - response may occur late or even after 6 months in some patients, particularly those with higher baseline migraine burden and prior treatment failures 4
• Do not assume all patients will respond equally - patients with medication overuse headache and psychiatric comorbidities have lower response rates and may require additional interventions 4
• Do not overlook the need for insurance authorization - the high cost necessitates prior authorization processes that can delay treatment initiation 1