Galcanezumab

• Migraine Prevention
• Episodic Cluster Headache
• Chronic Migraine
• CGRP-Targeted Therapy

Galcanezumab is a humanized monoclonal antibody that targets calcitonin gene-related peptide (CGRP) ligand, approved for the preventive treatment of migraine and episodic cluster headache. This biologic provides a once-monthly dosing option for patients with these debilitating headache disorders.

Mechanism of Action

Galcanezumab is a humanized IgG4 monoclonal antibody that binds to calcitonin gene-related peptide (CGRP) with high affinity and specificity. CGRP is a neuropeptide that plays a crucial role in the pathophysiology of migraine and cluster headache. It is released from trigeminal sensory neurons during headache attacks and contributes to vasodilation, neurogenic inflammation, and pain transmission. By binding and sequestering CGRP, galcanezumab prevents it from interacting with its receptor, thereby reducing CGRP-mediated signaling and decreasing the frequency and severity of headache attacks.

Available Formulations

Galcanezumab is available as a solution for subcutaneous injection in single-dose prefilled pens and prefilled syringes containing 120 mg/mL. The medication requires refrigeration but can be kept at room temperature (up to 86°F/30°C) for up to 7 days. Patients can self-inject after proper training. Injection sites include the abdomen, thigh, back of upper arm, or buttocks.

Medical Uses

Galcanezumab is FDA-approved for the preventive treatment of migraine in adults and for the treatment of episodic cluster headache in adults. For migraine, it is effective for both episodic and chronic migraine. Clinical trials demonstrated significant reductions in monthly migraine days and cluster headache attack frequency compared to placebo. The medication is not intended for acute treatment of migraine or cluster headache attacks.

Dosing Guidelines

For migraine prevention, the recommended dose is a loading dose of 240 mg (two 120 mg injections) followed by 120 mg monthly. For episodic cluster headache, the dose is 300 mg (three 100 mg injections or from 120 mg presentations as directed) at the onset of the cluster period, then monthly until the cluster period ends. Injections should be given at approximately the same time each month. No dose titration is required.

Important Safety Information

Hypersensitivity reactions including rash, urticaria, dyspnea, and anaphylaxis have been reported. The medication should be discontinued if serious hypersensitivity reaction occurs. Galcanezumab is contraindicated in patients with serious hypersensitivity to galcanezumab or any of its excipients. Injection site reactions have been reported and are generally mild and transient.

Drug Interactions

No formal drug interaction studies have been conducted. Galcanezumab is not expected to be metabolized by cytochrome P450 enzymes as it is a monoclonal antibody eliminated through catabolism. Based on clinical trial experience, it can be used concomitantly with acute migraine treatments and other preventive medications without known interactions.

Special Populations

There are no adequate data on galcanezumab use during pregnancy. Animal studies did not show evidence of fetal harm. Women should be advised of the lack of human data. It is unknown whether galcanezumab is excreted in human breast milk; consider the developmental and health benefits of breastfeeding. Safety and efficacy have not been established in pediatric patients. Clinical trials included patients up to 65 years for migraine and older for cluster headache; no overall differences in safety or efficacy were observed in elderly patients. No dose adjustment is needed for renal or hepatic impairment.