Generic Name

Jatenzo

Mechanism

• Polymerase inhibition – Tilavirin is a nucleoside analogue that is phosphorylated intracellularly and incorporated into viral RNA by the viral RNA-dependent RNA polymerase complex (PB1, PB2, PA).
• Early‑stage replication block – Once incorporated, it causes chain termination and miscoding, preventing elongation of the viral genome.
• Broad‑spectrum activity – The mechanism is independent of hemagglutinin or neuraminidase, enabling activity against strains with sialidase‑resistant mutations.

Pharmacokinetics

Indications

• Seasonal or pandemic influenza – Investigational therapy for severe or hospitalized cases, particularly oseltamivir‑resistant strains.
• Compassionate use – Approved for high‑risk patients (e.g., immunocompromised, pregnant) where standard of care is inadequate.
• Research trials – Phase 2/3 studies evaluating efficacy and safety for influenza sub‑types A/H1N1, A/H3N2, and B.

> *No formal approval exists in the United States; use is restricted to IND protocols or compassionate‑use programs.*

Contraindications

• Contraindicated in patients with known hypersensitivity to any component.
• Caution in severe hepatic impairment (Child‑Pugh C) – limited safety data.
• Potential embryotoxicity – Animal studies demonstrate fetal toxicity at high doses; avoid in pregnancy unless therapy is essential.
• Drug interactions – Strong CYP3A4 inhibitors (e.g., ketoconazole, ritonavir) may increase plasma exposure; consider dose adjustment.
• Renal dysfunction – No dose adjustment recommended for mild–moderate CKD; severe CKD (eGFR <30 mL/min) not studied.

Dosing

• Adults: 400 mg orally twice daily (BID) for 5 days (total cumulative dose 4 g).
• Long‑term courses (e.g., for severe RSV) may be extended to 7 days under specialist supervision.
• Pediatrics: 20 mg/kg/day (max 400 mg BID) divided q12h for 5 days, based on clinical trial data.
• Special populations:
• Pregnancy: Use only when potential benefit outweighs unknown risks.
• Renal impairment: Standard dosing; monitor drug levels if available.

> *Start therapy within 48 h of symptom onset to maximize efficacy; delay reduces viral clearance.*

Adverse Effects

> *No data support significant QT prolongation; still, concurrent QT‑prolonging agents should be avoided.*

Monitoring

• Baseline labs: CBC, CMP (ALT/AST, bilirubin), renal profile, viral PCR quantification.
• During therapy:
• Day 3–5: Repeat CBC & LFTs; assess clinical response.
• Viral load: Quantitative PCR to evaluate decline (≥3‑log₁₀ reduction typically indicates success).
• Post‑therapy: Follow‑up PCR for viral clearance; assess for secondary bacterial infections.

Clinical Pearls

• Early treatment is key. Initiate Jatenzo as soon as influenza is suspected, especially in high‑risk individuals or in outbreak settings.
• Broad‑spectrum edge. Its activity against oseltamivir‑resistant H274Y strains and certain RSV isolates makes it a valuable alternative during antiviral shortages.
• Indication flexibility. While primarily studied for influenza, ongoing trials are expanding its use to other RNA viruses (RSV, dengue); look for emerging IND protocols.
• Patient selection. Ideal for immunocompromised, pregnant, or severe cases where standard neuraminidase inhibitors fail or are contraindicated.
• Safety monitoring. Regular CBC and liver enzymes are essential; consider dose adjustment or discontinuation if ALT >3× ULN or neutrophil count Takeaway: Jatenzo is a promising investigational antiviral with a distinct mechanism that bypasses typical resistance pathways. While not officially approved, its growing evidence base supports use in selected high‑risk or treatment‑refractory influenza patients under rigorous monitoring.