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). |
| 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 | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for XOLAIR (XOLAIR).
| Breastfeeding | Present in breast milk in low levels; M/P ratio unknown. Consider developmental benefits of breastfeeding versus potential for adverse effects. Caution advised. |
| 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 |
■ 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 ingredient","Severe acute bronchospasm or status asthmaticus (not for acute rescue)"]
| 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"] |
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| 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. |