Migraine and CGRP inhibitors

Deep Dive

From a western clinical standpoint, migraine arises when the trigeminovascular system becomes hyperexcitable. Peripheral trigeminal afferents re... From a western clinical standpoint, migraine arises when the trigeminovascular system becomes hyperexcitable. Peripheral trigeminal afferents release neuropeptides, prominently calcitonin gene–related peptide (CGRP). CGRP binds to receptors on vascular smooth muscle and meningeal immune cells, producing vasodilation, mast cell activation, and a feed-forward loop of neuronal sensitization that propagates pain. Elevated CGRP during attacks and normalization after effective therapy, alongside the ability of CGRP infusion to trigger migraine-like headaches, firmly implicate this peptide in attack biology. People with chronic migraine and those with prominent central sensitization features (e.g., cutaneous allodynia) often show higher interictal CGRP levels, suggesting sustained pathway upregulation. Targeting this pathway has reshaped prevention and acute care. Monoclonal antibodies against the CGRP ligand (galcanezumab, fremanezumab, eptinezumab) or its receptor (erenumab) are administered monthly or quarterly. Across pivotal trials, they reduce monthly migraine days by roughly 1–2 more than placebo and increase the odds of 50% response by about 10–20% over placebo. Onset is frequently observed within the first 1–4 weeks, and eptinezumab has shown day-1 onset after infusion. Small-molecule CGRP receptor antagonists—ubrogepant and rimegepant for acute treatment, zavegepant as an intranasal acute option, and atogepant for prevention—provide 2-hour pain freedom and symptom relief rates superior to placebo and yield modest preventive gains. Safety profiles are favorable compared with many traditional preventives. Common adverse effects include injection-site reactions and constipation with mAbs, and nausea, somnolence, or dysgeusia with gepants. Postmarketing surveillance notes a hypertension signal with erenumab. Because CGRP supports physiologic vasodilation, prudence is warranted in patients with severe or unstable cardiovascular disease, though these agents themselves do not cause vasoconstriction. Data in pregnancy, lactation, and pediatrics remain limited; regulatory approvals are largely for adults. Gepants have drug–drug interaction considerations (e.g., CYP3A4), whereas mAbs have minimal pharmacokinetic interactions. In the broader treatment landscape, CGRP inhibitors compare favorably to traditional preventives (beta-blockers, topiramate, tricyclics) on tolerability and often on speed of benefit, though absolute efficacy gains are modest and costs higher. They can be combined with behavioral therapies, sleep optimization, trigger management, and, in select cases, onabotulinumtoxinA. Shared decision-making weighs attack frequency, prior treatment trials, comorbidities, patient preferences, route and frequency of administration, and access constraints.