Generic Name

Idhifa

Mechanism

Idhifa is a humanized monoclonal antibody that selectively binds to interleukin‑17A (IL‑17A), neutralizing its interaction with the IL‑17 receptor on keratinocytes and immune cells. By blocking IL‑17A signaling, Idhifa dampens the inflammatory cascade that drives keratinocyte hyperproliferation and neutrophil influx characteristic of moderate‑to‑severe plaque psoriasis.
• Target: IL‑17A (human cytokine).
• Result: ↓ Th17‑mediated inflammation → ↓ keratinocyte growth, ↓ scaling, ↓ erythema.

Pharmacokinetics

• Drug–Drug Interactions: Minimal; no clinically relevant CYP450 inhibition or induction.

Indications

• Moderate‑to‑Severe Plaque Psoriasis in adults who are inadequate responders to conventional systemic therapy or phototherapy.
• Psoriatic Arthritis (PsA): Approved for patients with active peripheral arthritis unresponsive or intolerant to ≥1 conventional disease‑modifying antirheumatic drugs (DMARDs).
• Off‑label: Investigation in axial spondyloarthritis and hidradenitis suppurativa.

Contraindications

• Contraindications
• Active, uncontrolled infections, especially tuberculosis, fungal, or opportunistic infections.
• History of severe hypersensitivity to monoclonal antibodies.
• Warnings
• Infection Risk: ↑ risk of upper respiratory tract infections, cellulitis, and Candida infections.
• Malignancy: Potential risk in patients with a history of cancer; use cautiously.
• Pregnancy & Lactation: Pregnancy category B; avoid definitive use in pregnancy unless benefits outweigh risks.

Dosing

• Loading Dose: 300 mg IV over 30 min on day 1.
• Maintenance: 150 mg IV every 4 weeks (or every 3 weeks for severe disease flares).
• Renal/Hepatic Impairment: No dose adjustment required; monitor closely.
• Infusion Protocol: Assess baseline vitals; pre‑medicate with antihistamine if history of infusion reactions.

Adverse Effects

• Common (≥10 %)
• Infusion reaction (fever, chills, flushing).
• Upper respiratory tract infections (nasopharyngitis).
• Injection site reaction (rare for IV).
• Headache.
• Serious (≤1 %)
• Severe hypersensitivity reaction (anaphylaxis).
• Opportunistic infections (tuberculosis, fungal).
• Cytopenias (pancytopenia).
• Re‑activation of latent viral infections (HBV).

Monitoring

• Baseline: CBC, CMP, hepatitis B/C serology, TB screening (IGRA or TST).
• During Treatment:
• CBC and CMP every 4 weeks.
• Clinic review for signs of infection, new respiratory symptoms, or rash.
• Every 6 months: Re‑screen for TB and hepatitis B if high risk.

Clinical Pearls

• Optimize for Comorbid Psoriasis: Patients with concomitant psoriatic arthritis respond better if the anti‑IL‑17 pathway is targeted early.
• TB Screen is Non‑negotiable: A negative IGRA/TST must be confirmed before the first infusion; consider prophylactic isoniazid if latent TB is detected.
• Re‑Dose Flexibility: Switching to every‑3‑week dosing can help in breakthrough disease but requires close monitoring of serum trough levels (~3 weeks after last dose).
• Minimal Drug Interactions: Because Idhifa has no CYP interactions, it can coexist safely with oral antihypertensives, statins, and most antibiotics.
• Patient Education: Counsel patients to seek prompt evaluation of fever, cough, or unexplained fatigue, as these may herald serious infection.
• Pregnancy Planning: Contraception is advised for 6 months after the last infusion due to the long half‑life.

--
• Key takeaways for practitioners
• Idhifa offers a robust, targeted therapy for plaque psoriasis and PsA with a favorable safety profile when infection risk is managed.
• Its long half‑life allows convenient quarterly dosing while maintaining steady therapeutic levels.
• Vigilant infection screening and patient counseling remain paramount to maximizing benefit and minimizing adverse events.