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Biologic — Anti-IL-5 Monoclonal Antibody

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.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

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. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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