Zanamivir

Inhalation
Influenza A and B
Adult: As powder for oral inhalation: 10 mg (2 inhalations) bid for 5 days via inhalation device. Initiate treatment within 48 hours after onset of symptoms.
Child: As powder for oral inhalation: ≥5 years 10 mg (2 inhalations) bid for 5 days via inhalation device. Initiate treatment within 36 hours after onset of symptoms. Dosing recommendations may vary among individual products and between countries (refer to specific product guidelines).

Inhalation
Prophylaxis of influenza A and B
Adult: As powder for oral inhalation: Household or close contact exposure: 10 mg (2 inhalations) once daily for 10 days via inhalation device. Community outbreak: 10 mg (2 inhalations) once daily for up to 28 days via inhalation device. Initiate treatment within 36 hours of exposure.
Child: ≥5 years Same as adult dose. Dosing recommendations may vary among individual products and between countries (refer to specific product guidelines).

Intravenous
Influenza A and B
Adult: In patients with complicated and potentially life-threatening infection, resistant and/or unsuitable to other treatments: 600 mg bid for 5-10 days, via infusion over 30 minutes. Initiate treatment within 6 days of the onset of symptoms.
Child: In patients with complicated and potentially life-threatening infection, resistant and/or unsuitable to other treatments: As zanamivir hydrate: 6 months to <6 years 14 mg/kg bid. ≥6 years 12 mg/kg bid; max: 600 mg bid. All doses are given via infusion over 30 minutes. Treatment duration: 5-10 days.
Renal impairment: Patients on intermittent haemodialysis or peritoneal dialysis, dose is given after dialysis session.

CrCl (ml/min)	Dosage Recommendation
50-<80	6 years to <18 years weighing <50 kg: Initially, 12 mg/kg followed by 8 mg/kg bid, to be started 12 hours after initial dose.
<15	Adult and children ≥6 years weighing ≥50 kg: Initially, 600 mg followed by 60 mg bid, to be started 48 hours after initial dose.
15-<30	Adult and children ≥6 years weighing ≥50 kg: Initially, 600 mg followed by 150 mg bid, to be started 24 hours after initial dose.
30-<50	Adult and children ≥6 years weighing ≥50 kg: Initially, 600 mg followed by 250 mg bid, to be started 12 hours after initial dose.
50-<80	Adult and children ≥6 years weighing ≥50 kg: Initially, 600 mg followed by 400 mg bid, to be started 12 hours after initial dose.
<15	6 years to <18 years weighing <50 kg: Initially, 12 mg/kg followed by 1.2 mg/kg bid, to be started 48 hours after initial dose.
15-<30	6 years to <18 years weighing <50 kg: Initially, 12 mg/kg followed by 3 mg/kg bid, to be started 24 hours after initial dose.
30-<50	6 years to <18 years weighing <50 kg: Initially, 12 mg/kg followed by 5 mg/kg bid, to be started 12 hours after initial dose.
<15	6 months to <6 years weighing ≥42.8 kg: Initially, 600 mg followed by 60 mg bid, to be started 48 hours after initial dose.
15-<30	6 months to <6 years weighing ≥42.8 kg: Initially, 600 mg followed by 150 mg bid, to be started 24 hours after initial dose.
30-<50	6 months to <6 years weighing ≥42.8 kg: Initially, 600 mg followed by 250 mg bid, to be started 12 hours after initial dose.
50-<80	6 months to <6 years weighing ≥42.8 kg: Initially, 600 mg followed by 400 mg bid, to be started 12 hours after initial dose.
<15	6 months to <6 years: Initially, 14 mg/kg mg followed by 1.4 mg/kg bid, to be started 48 hours after initial dose.
15-<30	6 months to <6 years weighing <42.8 kg: Initially, 14 mg/kg followed by 3.5 mg/kg bid, to be started 24 hours after initial dose.
30-<50	6 months to <6 years
50-<80	6 months to <6 years weighing <42.8 kg: Initially, 14 mg/kg followed by 9.3 mg/kg bid, to be started 12 hours after initial dose.

Reconstitution: IV infusion: May infuse undiluted or dilute in 0.9% NaCl inj to a final concentration of ≥0.2 mg/mL.

Hypersensitivity.

Patient with underlying respiratory disease (e.g. severe asthma, persistent asthma, severe COPD), unstable chronic illness. Immunocompromised, nursing home patients. Not a substitute for influenza vaccination. Renal impairment (IV). Children. Pregnancy and lactation. Monitoring Parameters Monitor for behavioural changes. Evaluate benefits and risks of continuing treatment. Monitor respiratory function.

Significant: Allergic reactions (e.g. anaphylaxis, facial and oropharyngeal oedema, serious skin rashes [e.g. erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis]). Rarely, neuropsychiatric events in paediatric patients (e.g. confusion, delirium, hallucinations, seizure, self-injury); hepatocellular injury (IV). Gastrointestinal disorders: Abdominal pain; diarrhoea (IV). Investigations: Increased ALT, increased AST (IV). Nervous system disorders: Vasovagal-like reactions (in patients with influenza symptoms), dizziness. Respiratory, thoracic and mediastinal disorders: Dyspnoea, throat tightness or constriction. Skin and subcutaneous tissue disorders: Rash, urticaria.
Potentially Fatal: Bronchospasm, decreased lung function.

May decrease the therapeutic effect of live or attenuated influenza virus vaccine.

Zanamivir selectively inhibits influenza virus neuraminidase surface enzyme, thus potentially altering the virus particle aggregation and release. It reduces reproduction of both influenza A and B viruses by suppressing the release of infective influenza virions from the epithelial cells of the respiratory tract.
Absorption: Poorly absorbed from the gastrointestinal tract. Bioavailability: 2% (oral). Time to peak plasma concentration: 1-2 hours (inhalation).
Distribution: Widely deposited throughout the respiratory tract after oral inhalation. Volume of distribution: Approx 16 L. Plasma protein binding: <10%.
Excretion: Via urine (as unchanged drug); faeces (unabsorbed drug). Elimination half-life: 2.5-5.1 hours (oral inhalation); approx 2-3 hours (IV).

Inhalation: Store below 30°C. Intravenous: Store diluted solution between 2-8°C for up to 24 hours.

Antivirals

J05AH01 - zanamivir ; Belongs to the class of neuraminidase inhibitors. Used in the systemic treatment of viral infections.