Anti-IgE Monoclonal Antibody Pregnancy: Use with caution — IgG antibody crosses placenta; limited pregnancy data; use if clearly needed

Omalizumab (CRSwNP)

Brand names: Xolair

Adult dose

Dose: 75–600 mg SC every 2–4 weeks (IgE/weight-based dosing table); CRSwNP: typically 300 mg every 4 weeks

Route: Subcutaneous injection

Frequency: Every 2–4 weeks (dose table)

Max: 600 mg per dose (IgE/weight-dependent)

CRSwNP add-on to intranasal steroids; IgE 30–1500 IU/mL and weight-based dosing; different from fixed 300 mg used in chronic urticaria

Paediatric dose

Dose: Not established for CRSwNP <18 years N/A/kg

Route: N/A

Frequency: N/A

Max: N/A

Allergic asthma licensed ≥6 years; CRSwNP adults only

Dose adjustments

Renal

No dose adjustment required

Hepatic

No dose adjustment required

Paediatric weight-based calculator

Patient weight (kg)

Allergic asthma licensed ≥6 years; CRSwNP adults only

Clinical pearls

POLYP 1 and POLYP 2 trials (Gevaert et al. NEJM 2019): omalizumab significantly reduced nasal polyp score and congestion vs placebo at 24 weeks — NICE TA671 approved for CRSwNP; serum IgE and blood eosinophil levels predicted response
IgE-mediated mechanism in CRSwNP: local IgE production in nasal polyp tissue drives mast cell activation and perpetuates type 2 eosinophilic inflammation — omalizumab reduces free IgE, downregulates FcεRI receptors, and decreases mast cell and basophil sensitivity
Biomarker-guided prescribing: patients with higher serum IgE (>100 IU/mL) and blood eosinophils (≥260 cells/μL) respond best — useful for treatment selection between dupilumab, mepolizumab, and omalizumab
Concurrent allergic asthma: omalizumab treats both conditions — particularly valuable in patients with IgE-mediated (atopic) CRSwNP and allergic asthma; single agent addresses both
NICE TA671: requires inadequate response to intranasal corticosteroids after ≥4 weeks AND at least one of: prior nasal surgery or contraindication to surgery, systemic corticosteroid use ≥2 courses in past year, significantly impaired QoL

Contraindications

Known hypersensitivity to omalizumab
Total IgE <30 or >1500 IU/mL (outside dosing table)

Side effects

Injection site reactions
Anaphylaxis (rare — observe 30 min after first 3 doses)
Headache
Arthralgia
Eosinophilic conditions (rare — Churg-Strauss)

Interactions

Live vaccines — caution

Monitoring

Nasal polyp score and SNOT-22 at 16 weeks (response assessment)
Total IgE (baseline — for dosing)
Anaphylaxis observation (30 min post-injection)
Eosinophil count

Reference: BNFc; BNF 90; POLYP 1 & 2 trials (Gevaert et al. NEJM 2019); NICE TA671; MHRA SPC Xolair; EPOS 2020. Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

Calculators

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