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Biologic DMARD — Dual IL-17A and IL-17F Inhibitor Pregnancy: Avoid — insufficient data; no identified teratogenic signal in limited animal studies

Bimekizumab

Brand names: Bimzelx

Adult dose

Dose: 160 mg subcutaneous injection
Route: Subcutaneous
Frequency: Every 4 weeks for first 6 months, then every 8 weeks
Max: 160 mg every 4 weeks (active PsA); 160 mg every 8 weeks (maintenance)
First and only biologic to simultaneously inhibit both IL-17A and IL-17F (unlike secukinumab and ixekizumab which inhibit IL-17A only). Approved for psoriatic arthritis, plaque psoriasis, and ankylosing spondylitis. Prefilled pen — allow to reach room temperature for 30 minutes before injection.

Paediatric dose

Route:
Not licensed for paediatric use — seek specialist opinion

Dose adjustments

Renal

No dose adjustment required

Hepatic

No dose adjustment required

Clinical pearls

  • First dual IL-17A/F inhibitor: IL-17F, long overlooked, contributes significantly to mucosal inflammation and skin disease — dual blockade achieves superior skin clearance and joint outcomes compared to IL-17A alone
  • BE OPTIMAL trial (NEJM 2023): bimekizumab achieved PSARC response in 70% vs 32% placebo and MDA (minimal disease activity) in 45% vs 10% — landmark results for biologic-naive PsA patients
  • Oral candidiasis: substantially higher rate than secukinumab (IL-17A only) — dual IL-17A/F blockade impairs mucosal antifungal defence more comprehensively; nystatin mouthwash prophylaxis or ready access to treatment advised
  • IBD risk: all IL-17 inhibitors are associated with new onset or worsening of IBD — contraindicated in active Crohn's disease; use with caution in patients with IBD history
  • MHRA 2023 approval for PsA and plaque psoriasis — BE ACTIVE, BE OPTIMAL, and BE VIVID trials established efficacy; NICE appraisal ongoing at time of approval

Contraindications

  • Active serious infection
  • Active Crohn's disease — IL-17 inhibition associated with IBD exacerbation
  • Hypersensitivity to bimekizumab
  • Live vaccines

Side effects

  • Oral candidiasis — most distinctive and frequent side effect (due to dual IL-17A + IL-17F blockade); significantly higher than secukinumab (IL-17A only)
  • Upper respiratory tract infections
  • Injection site reactions
  • Tinea infections
  • IBD new onset or exacerbation — screen for IBD history
  • Conjunctivitis

Interactions

  • Live vaccines — contraindicated
  • CYP450 substrates — possible alteration via IL-17 axis effects; warfarin and ciclosporin monitoring
  • Other immunosuppressants — increased infection risk

Monitoring

  • Signs of infection — especially oral candidiasis at each visit
  • IBD symptoms — new abdominal pain, blood PR, change in bowel habit
  • TB screening before initiation
  • Clinical response at 16–24 weeks
  • Skin surveillance

Reference: BNFc; BNF 90; BE OPTIMAL Trial (NEJM 2023); BE ACTIVE Trial (Ann Rheum Dis 2023); MHRA Approval Bimzelx 2023; SPC Bimzelx. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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