XOLAIR
Clinical safety rating: caution
Comprehensive clinical and safety monograph for XOLAIR (XOLAIR).
Recombinant humanized monoclonal antibody that binds to free immunoglobulin E (IgE), preventing IgE from binding to high-affinity FcεRI receptors on mast cells and basophils, thereby inhibiting allergen-induced release of mediators.
| Metabolism | Degraded by reticuloendothelial system and target-mediated clearance via binding to IgE; no cytochrome P450 involvement. |
| Excretion | Omalizumab undergoes proteolytic degradation and is eliminated via reticuloendothelial system (RES) and catabolism; renal excretion is minimal. Biliary/fecal excretion of intact drug is negligible; metabolites are excreted in urine and feces. |
| Half-life | Terminal elimination half-life is approximately 26 days (range 20–30 days) in patients with asthma. This long half-life supports every 2- or 4-week dosing. Half-life decreases with higher body weight and baseline IgE levels. |
| Protein binding | Omalizumab binds specifically to free IgE (high affinity); no significant binding to other plasma proteins. As a monoclonal antibody, it does not bind to albumin or α1-acid glycoprotein. Binding to free IgE is >95%. |
| Volume of Distribution | Approximately 0.06 L/kg (range 0.04–0.08 L/kg) in adults after subcutaneous administration. This low Vd (equivalent to plasma volume) indicates minimal extravascular distribution, consistent with a large monoclonal antibody that remains primarily in the vascular space. |
| Bioavailability | Subcutaneous: Absolute bioavailability is approximately 62% (range 50–70%) after injection into the arm or thigh. Bioavailability is not affected by injection site (arm, thigh, abdomen) in clinical studies. |
| Onset of Action | Subcutaneous: Clinical improvement (reduction in asthma exacerbations) is observed within 4–8 weeks of starting therapy; maximum effect may take 12–16 weeks. No IV formulation available. |
| Duration of Action | Duration of therapeutic effect is sustained with regular dosing (every 2–4 weeks). After discontinuation, drug levels decline slowly; clinical benefit may persist for weeks to months but eventually wanes as IgE levels return to pretreatment values (within 6–12 months). |
| Molecular Weight | 149000 |
| Action Class | Anti IgE monoclonal antibodies |
| Brand Substitutes | Bolstran 150mg Injection, Emzumab 150mg Injection, Omalirel Injection |
150–375 mg subcutaneously every 2 or 4 weeks; dose and frequency based on baseline serum IgE (IU/mL) and body weight (kg) per dosing table.
| Dosage form | VIAL |
| Renal impairment | No dose adjustment required for renal impairment; not studied in severe renal impairment. |
| Liver impairment | No formal studies; no specific dose adjustment recommended based on Child-Pugh class. |
| Pediatric use | Approved for ages ≥6 years with allergic asthma: dose (mg) and frequency determined by weight (15–150 kg) and baseline IgE (30–1500 IU/mL) using the Xolair dosing table. For chronic spontaneous urticaria: ages ≥12 years, 150–300 mg every 4 weeks. |
| Geriatric use | No specific dose adjustment in elderly; use caution due to higher incidence of adverse events (e.g., anaphylaxis, injection site reactions) and comorbidities. |
| 1st trimester | Limited data; use only if clearly needed. IgG antibodies cross placenta minimally in first trimester, but theoretical risk of fetal harm exists. |
| 2nd trimester | Use only if potential benefit justifies risk. Omalizumab is an IgG1 monoclonal antibody; placental transfer increases as pregnancy progresses. |
| 3rd trimester | Use with caution; may cross placenta more readily in third trimester. There is a risk of neonatal Fc receptor-mediated transfer, but limited human data suggest no major teratogenicity. |
Clinical note
Comprehensive clinical and safety monograph for XOLAIR (XOLAIR).
| Placental transfer | Omalizumab is a humanized IgG1 monoclonal antibody. Like other IgG antibodies, it crosses the placenta by active transport via neonatal Fc receptors, with transfer increasing progressively during the second and third trimesters. Detectable levels in cord blood have been reported. First trimester transfer is minimal. |
| Breastfeeding |
■ FDA Black Box Warning
Anaphylaxis can occur after administration, even in patients who have tolerated previous doses. Observe patients for a period of time after injection. Discontinue if severe hypersensitivity reaction occurs.
| Serious Effects |
Hypersensitivity to omalizumab or any excipientsSevere allergic reaction to omalizumab in the past
| Precautions | Risk of anaphylaxis, Malignancy observed in clinical trials, Eosinophilic conditions, Serum sickness and delayed hypersensitivity reactions, Parasitic infections (increased risk), Do not abruptly discontinue systemic or inhaled corticosteroids upon initiation |
| Food/Dietary | No known food interactions. Avoid if allergic to any components (recombinant DNA-derived monoclonal antibody). No dietary restrictions. |
Loading safety data…
| Omalizumab is a large protein molecule; minimal excretion into breast milk is expected. Based on limited case reports, no adverse effects in breastfed infants have been reported. Consider benefits of breastfeeding and importance of drug to mother. |
| Lactation Rating | L3: Probably Compatible |
| Teratogenic Risk | Insufficient human data; animal studies showed no evidence of fetal harm. IgG antibodies cross placenta minimally in first trimester, increasing in second and third trimesters. Risk cannot be excluded; use only if clearly needed. |
| Fetal Monitoring | Monitor for signs of anaphylaxis or hypersensitivity reactions; assess asthma control and lung function periodically. |
| Fertility Effects | No evidence of impaired fertility based on animal studies; human data not available. |
| Clinical Pearls | XOLAIR (omalizumab) is a monoclonal anti-IgE antibody for moderate-to-severe persistent allergic asthma and chronic idiopathic urticaria. Administer subcutaneously every 2-4 weeks based on pretreatment IgE levels and body weight. Monitor for anaphylaxis for 2 hours after first 3 injections and 30 minutes thereafter. Do not use in acute bronchospasm or status asthmaticus. Significant reduction in IgE levels occurs within 1 hour; clinical response may take weeks. Do not abruptly discontinue systemic corticosteroids; taper gradually. |
| Patient Advice | XOLAIR is not a rescue medication and should not be used to treat sudden asthma attacks. · Report any signs of allergic reaction (hives, swelling, difficulty breathing) immediately after injection. · Continue taking other asthma medications unless your doctor advises otherwise. · Store XOLAIR vials in the refrigerator, do not freeze, and protect from light. · Keep a record of injection dates and any symptoms between visits. |