Generic Name

Emgality

Mechanism

• Selective CGRP ligand inhibition – Galcanezumab binds with high affinity to CGRP, preventing it from interacting with the CGRP receptor on trigeminal vascular pathways.
• Rescues the vasodilatory and neurogenic inflammatory cascade responsible for migraine initiation.
• Does not cross the blood–brain barrier in significant amounts; action is peripherally mediated.

Pharmacokinetics

• Route: Subcutaneous injection.
• Absorption: Linear, peak serum concentrations reached 4–7 days post‑dose.
• Bioavailability: ~70 % after SC administration.
• Volume of distribution: ~5 L (reflects limited tissue penetration).
• Half‑life: ~27 days (steady‑state reached in ~3 months).
• Metabolism: Cleaved into peptides via proteolysis; not dependent on hepatic CYP enzymes.
• Excretion: Primarily through proteolytic catabolism; no renal clearance considerations.

Indications

• Preventive treatment of episodic migraine (≥4 and ≤14 headache days/28 days).
• Preventive treatment of chronic migraine (≥15 headache days/28 days) in adults.

*Not indicated for acute migraine relief or for use in children under 12.*

Contraindications

• Contraindicated:
• Known hypersensitivity to galcanezumab or any excipient.
• Warnings/Precautions:
• Pregnancy – No definitive safety data; use only if benefits outweigh risks.
• Breast‑feeding – Limited data; consider discontinuation.
• Impaired renal/hepatic function – No dose adjustment required, but monitor for hypersensitivity.
• Adverse reactions – Monitor for signs of anaphylaxis or severe injection‑site reactions.

Dosing

• Use a prefilled syringe or prefilled needle‑free system.
• Rotate injection sites (abdomen, thigh, upper arm).
• Allow the solution to equilibrate to room temperature before injection (≈10 min).

Adverse Effects

Common (≥2 % incidence):
• Injection‑site reactions (pain, erythema, induration)
• Constipation
• Headache
• Upper respiratory tract infection

Serious (≤1 % incidence):
• Hypersensitivity/anaphylactic reactions
• Serious injection‑site events (necrotizing fasciitis reported in post‑marketing)
• Potential for acute hypertension (rare).

*Monitor patient for any signs of systemic hypersensitivity; discontinue if severe reaction occurs.*

Monitoring

• Injection‑site inspection: Document pain, erythema, swelling; advise proper technique.
• Blood pressure: Baseline and periodic checks if patient has hypertension or renal disease.
• Medication Review: Identify concomitant migraine prophylactics; watch for additive effects.
• Pregnancy Test: For women of childbearing potential; counsel regarding contraception.

Clinical Pearls

• Convenient dosing: Monthly SC injections make adherence easier than daily oral preventives.
• Rapid onset: Clinical benefit may be seen within 1–2 weeks, often earlier than other biologics.
• Combination therapy: Safe to use with other migraine preventives (e.g., topiramate, propranolol) – no pharmacokinetic interaction as it is not metabolized by CYP450.
• Vaccine timing: Avoid intramuscular vaccinations at injection sites to minimize reaction risk.
• Re‑initiation after discontinuation: A brief washout (≈3 months) may be needed to achieve adequate serum levels if therapy is paused.
• Safety in pregnancy: MRI-based evidence of no significant teratogenicity, but still categorized as pregnancy category B; counsel patients accordingly.
• Adherence aids: Pre‑filled syringes have an integrated safety‑device latch that helps prevent accidental injections.

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• Reference: FDA label for Emgality (galcanezumab‑t.m.c.a), U.S. Food & Drug Administration, 2024. Use this drug card as a quick scan aid for migraine pharmacology, subcutaneous monoclonal antibody therapy, and preventive treatment strategies.