Mepolizumab (Eosinophilic GPA)
Brand names: Nucala
This is mepolizumab used in rheumatology for eosinophilic granulomatosis with polyangiitis (EGPA, formerly Churg–Strauss), given as a specialist-initiated subcutaneous injection to control eosinophilic vasculitic disease and reduce corticosteroid burden.
Adult dose
Dose adjustments
No dose adjustment is required in patients with renal or hepatic impairment.
Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.
Contraindications
- Hypersensitivity to the active substance or to any of the excipients
Side effects
- Headache (very common — 32% in the EGPA study)
- Injection site reactions (15% in the EGPA study) and back pain (13% in the EGPA study)
- Lower respiratory tract infection, urinary tract infection and pharyngitis (common)
- Systemic allergic (hypersensitivity) reactions — common, reported by 4% of EGPA patients; anaphylaxis is rare
- Nasal congestion (common)
- Herpes zoster (common)
Interactions
- Formal drug interaction trials have not been performed with mepolizumab (US labelling §7)
Clinical monograph
How it works
It is a monoclonal antibody against interleukin-5 (IL-5), reducing eosinophil production and survival that drive tissue damage in EGPA.
Prescribing in practice
- Hypersensitivity reactions, including delayed systemic reactions, can occur and require monitoring after administration.
- It is not a treatment for acute vasculitic flares, and existing immunosuppression or corticosteroids should not be stopped abruptly when starting it.
- Parasitic (helminth) infection should be treated before initiation, as eosinophils contribute to host defence.
Monitoring
Monitor for hypersensitivity and injection-site reactions and for clinical disease control allowing corticosteroid tapering, in line with the SPC.
Counselling the patient
- Report rash, swelling or breathing difficulty after an injection.
- Do not stop your steroids suddenly; reduce only as advised.
- Continue to report any return of vasculitis symptoms.
Evidence & guidelines
A randomised controlled trial in relapsing or refractory EGPA showed more accrued remission time and reduced oral corticosteroid use with mepolizumab.
Reference: NICE TA671; MIRRA Trial (NEJM 2017); EULAR EGPA Guidelines; SPC Nucala; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).
Related
Curated clinical cross-links plus same-class fallbacks.
- PASI Score (Psoriasis Area and Severity Index) · Psoriasis
- DLQI (Dermatology Life Quality Index) · Quality of Life
- Revised Original International Autoimmune Hepatitis Score (IAIHG) · Autoimmune Liver Disease
- Eosinophilic Oesophagitis Endoscopic Reference Score (EREFS) · Upper GI
- Index of Severity for Eosinophilic Oesophagitis (I-SEE) · Oesophageal Disease
- Ho Index for Predicting Response to Medical Therapy in IBD · Inflammatory Bowel Disease
- Cutaneous Lupus Erythematosus · BAD; EULAR
- Osteoporosis / Fragility Fracture · NOGG 2021; NICE NG147; NG224
- Arteritic AION (Giant Cell Arteritis) · RCOphth; BSR
- Osteoarthritis Hip / Knee Management · NICE NG226 (2022)
- Lupus Nephritis · EULAR/ERA-EDTA 2019; KDIGO 2024
- Rheumatoid Arthritis Management · NICE CG79 2018 / EULAR 2022