Oseltamivir
Mechanism :
Oseltamivir is a neuraminidase inhibitor. It acts as a transition-state analogue inhibitor of influenza neuraminidase, preventing progeny virions from emerging from infected cells.
Indication :
- Influenza infection and prophylaxis
Contraindications :
In patients allergic to oseltamivir.
Dosing :
Influenza Treatment:
Infants:
3 mg/kg/dose PO in 2 divided doses for 5 days.
1-13 years:
<15 kg: PO 30 mg twice daily for 5 days.
15-23 kg: PO 45 mg twice daily for 5 days.
23-40 kg: PO 60 mg twice daily for 5 days.
>40 kg: PO 75 mg twice daily for 5 days.
>13 years:
75 mg twice daily for 5 days PO, beginning within 2 days of onset of symptoms.
Influenza Prophylaxis:
If child is younger than 3 months old, use of oseltamivir for chemoprophylaxis is not recommended unless situation is judged critical due to limited data in this age group.
Infants:
3 months-1 year: 3 mg/kg/dose PO once daily for 7 days.
1-13 years:
<15 kg: PO 30 mg once daily for 7 days.
15-23 kg: PO 45 mg once daily for 7 days.
23-40 kg: PO 60 mg once daily for 7 days.
>40 kg: PO 75 mg once daily for 7 days.
>13 years:
PO 75 mg once daily for at least 7 days, starting within 2 days of exposure.
Adverse Effect :
Unstable angina, arrhythmia, confusion, delirium, seizures, self-injury, dermatitis, eczema, erythema multiforme, rash, Stevens-Johnson syndrome, toxic epidermal necrolysis, urticaria, conjunctivitis, vomiting, nausea, abdominal pain, pseudomembranous colitis, anemia, abnormal LFTs, aggravation of diabetes mellitus.
Interaction :
Live attenuated influenza vaccine. Because of potential interference between these products, avoid administration of live attenuated influenza vaccine within 2 weeks before or 48 h after oseltamivir.
Renal Dose :
Dose in Renal Impairment GFR (mL/min)
| 30-50 | Dose as in normal renal function |
| 10-30 | Treatment: 75 mg once daily or 30 mg twice daily Prophylaxis: 75 mg every 48 hours or 30 mg once daily |
| <10 | Treatment: 30 mg once off dose Prophylaxis: 30 mg every 10 days |
Dose in Patients undergoing Renal Replacement Therapies
| CAPD | Dialysed. Treatment: 30 mg stat; prophylaxis: 30 mg weekly |
| HD | Dialysed. Treatment: 30 mg stat; prophylaxis: 30 mg after alternate dialysis sessions |
| HDF/High flux | Dialysed. Treatment: 30 mg stat; prophylaxis: 30 mg after alternate dialysis sessions |
| CAV/VVHD | Unknown dialysability. Dose as in GFR=10–30 mL/min |
Hepatic Dose :
Mild to moderate hepatic impairment: No dosage adjustments are recommended.
Severe hepatic impairment: The safety has not been studied.