Omalizumab in dermatology
Omalizumab in dermatology is a recombinant humanized monoclonal antibody directed against IgE. It can be used in the following indications in dermatology.
Indications
- Refractory chronic spontaneous urticaria (add‐on therapy).
- Refractory cases of dermatographism.
- Refractory cholinergic urticaria.
- Refractory solar urticaria.
- Refractory cases of Cold urticaria.
- Refractory heat urticaria.
- Refractory delayed pressure urticaria.
- Resistant atopic dermatitis.
- Bullous pemphigoid.
- Hyper IgE syndrome.
- Job syndrome.
- Mastocytosis.
Mechanism of action
Omalizumab is a humanized monoclonal antibody (IgG1) which selectively binds to free immunoglobulin E antibodies and inhibits binding to IgE receptors on the surface of mast cells and basophils preventing release of inflammatory mediators. It was approved by the US Food and Drug Administration (FDA) in 2014 for chronic idiopathic urticaria unresponsive to high doses of H1 antihistamines in adults and children aged 12 years or older.
Dosage
- 150 or 300 mg administered subcutaneously every 4 weeks.
- Supervised administration remains the preferred approach.
Monitoring of Omalizumab
Baseline
- Routine history, clinical assessment.
- Blood tests (full blood count, liver function tests, renal function).
- Total blood IgE level : Non responders to Omalizumab had lower baseline total IgE. Pretreatment total IgE levels of less than 40 IU/mL, a cutoff that was found to be linked to autoimmune CSU.
Follow up
- Total blood IgE level.
Side effects
- Upper respiratory tract infections (sinusitis)
- Headache.
- Joint pain.
- Injection site reactions, urticaria and serum sickness.
- Nasopharyngitis.
- Gastrointestinal disorders.
- Anaphylaxis (0.2%) : may occur within the first 2 hours. There are reports of anaphylaxis occurring as early as the first dose and as late as one year after regularly scheduled treatment.
- Cardiovascular and cerebrovascular serious adverse events.
- Eosinophilic granulomatosis with polyangiitis.
- Hair loss.
- Thrombocytopenia.
- Abnormal immune responses to parasitic infections.
Contraindications
- Severe hypersensitivity reaction to Omalizumab.
Pregnancy &Lactation
- Omalizumab is a humanized monoclonal antibody (IgG1) and IgG crosses the placenta, so the fetus of a woman receiving omalizumab would be exposed to the drug.
- Omalizumab is pregnancy category B.
- IgG is excreted into human milk but the amount is very low. Omalizumab is considered acceptable to use during breastfeeding.
Precautions
- Inform the patient about the possibility of anaphylaxis and how to use epinephrine autoinjector to treat them.
- Administer only in a healthcare setting prepared to manage anaphylaxis.
- Anaphylaxis happens usually within 2 h of injection but occasionally up to 24 h post‐injection.
- Observe your patient for 2 hours after the first 3 injections and for 30 minutes after each subsequent injection.
- Omalizumab may present particular risk to patients with a susceptibility to helminthic/other parasitic infections in endemic areas.
- If any of the following manifestations develop, omalizumab should be stopped:
- Marked eosinophilia.
- Vasculitic rash,
- Worsening pulmonary symptoms in asthmatic patients.
- Paranasal sinus abnormalities.
- Cardiac complications.
- Neuropathy.
Drug Interactions
- No specific interactions.
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