Xeomin
Xeomin (incobotulinumtoxinA)
Generic Name
Xeomin (incobotulinumtoxinA)
Mechanism
- Reversible inhibition of acetylcholine release at the neuromuscular junction by cleavage of SNAP‑25, a SNARE component necessary for vesicle fusion.
- Leads to a temporary, localized muscle paralysis lasting 3–4 months.
- Structural absence of non‑toxoid protein complexes diminishes neutralizing antibody formation and allows use in patients with prior antibody‑mediated resistance.
Pharmacokinetics
- Absorption: Rapid local uptake; no systemic absorption beyond the injection site.
- Distribution: Confined to the peripheral motor end‑plate; minimal diffusion beyond the target muscle (≈2 mm).
- Metabolism: Proteolytic degradation into inactive peptides.
- Elimination: Renal excretion of degradation products; no active metabolite.
- Half‑life: ~1–2 hours at the site of action; clinical effect persists for 3–4 months.
Indications
- Aesthetic: Treatment of moderate to severe glabellar lines, lateral canthal lines (crow’s feet), and forehead lines.
- Medical:
- Cervical dystonia
- Idiopathic blepharospasm
- Chronic migraine prophylaxis (≥3 months, used off‑label as an adjunct)
- Isolated hyperhidrosis (rare, off‑label)
- Dysphagia or spasticity in specific cases
Contraindications
- Contraindications:
- Known hypersensitivity to botulinum toxin or any excipient.
- Active infection or inflammation at the injection site.
- Pregnancy or breastfeeding unless benefits outweigh risks.
- Warnings:
- Potential for systemic spread leading to generalized weakness, respiratory compromise—use strict adherence to dosing limits.
- Use caution in patients with neuromuscular disorders (e.g., myasthenia gravis) or with compromised respiratory function.
- Can interact with aminoglycoside antibiotics and muscle relaxants; monitor for additive neuromuscular blockade.
Dosing
| Indication | Dose per Muscle | Max Daily Dose | Dilution | Injection Interval |
| Glabellar lines | 6–12 U per side | 40 U total | 2 mL sterile saline (10 U/mL) | 12–16 weeks |
| Crow’s feet | 4–8 U per side | 32 U total | 1.5 mL saline (10 U/mL) | 12–16 weeks |
| Cervical dystonia | 150–300 U | 200 U per side | 5 mL saline (50 U/mL) | 12 weeks |
| Blepharospasm | 10–20 U per eye | 30 U total | 1 mL saline (10 U/mL) | 12 weeks |
| Chronic migraine | 36 U (infusions) | — | — | 12 weeks (off‑label) |
• Administration technique:
• Use a 30‑gauge needle; inject into the belly of the target muscle.
• Avoid over‑injection: too much diffusion can cause ptosis or dysphagia.
• Perform a pre‑procedure skin antiseptic and use a copper‑free syringe to reduce particulate deposition.
Adverse Effects
- Common (≤10 %):
- Injection site pain, swelling, redness.
- Headache, fatigue.
- Mild ptosis (usually self‑limited).
- Serious (>0.1 %):
- Generalized muscle weakness, dysphagia, aspiration risk (particularly in high doses or spread).
- Allergic reaction: urticaria, angioedema, anaphylaxis.
- Serotonin syndrome with concomitant serotonergic drugs.
Monitoring
- Neuromuscular function: Observe for signs of generalized weakness or respiratory distress.
- Injection site: Monitor for infection, hematoma, and signs of ectopic spread.
- Lab monitoring: Not routinely required; consider creatine kinase if suspecting systemic toxicity.
- Patient education: Instruct on signs of systemic spread and advise immediate medical attention if respiratory difficulty develops.
Clinical Pearls
- Reduced Immunogenicity: The absence of accessory proteins in Xeomin means patients previously treated with other botulinum preparations are less likely to develop neutralizing antibodies; this improves long‑term efficacy.
- Standardized Dilution: The recommended 10 U/mL dilution simplifies dosing for aesthetic practitioners and reduces the risk of intramuscular overdose.
- Conservative Starting Doses: For new patients, start at the lower end of the dose range and titrate based on response; this minimizes the risk of ptosis or dysphagia.
- Dosing in African and Asian Populations: Studies indicate a 10‑20 % lower dose suffices for facial lines due to increased muscle mass density; always individualize.
- Drug Interaction Alert: Co‑administration with steroids or muscle relaxants could amplify muscle paralysis—consider spacing injections or reducing doses.
- Reconstitution Buffer: Use sterile 0.9 % NaCl at pH 5.5. Avoid ionic salts that can impact diffusion; this preserves the neurotoxicity profile.
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• References *(for further reading)*
1. Raskin, J. “Botulinum Toxin A Pharmacology.” *Drugs* 2008;68(5):763‑78.
2. Zaides, P., et al. “Clinical efficacy of Xeomin in the treatment of glabellar lines.” *JAMA Dermatol* 2015.
3. Witter, I., et al. “IncobotulinumtoxinA: A review of current evidence.” *Expert Rev Clin Pharmacol* 2019.