oseltamivir phosphate: prescribing and clinical use
Focused clinical detail for use alongside current product information, local policy and patient-specific assessment.
oseltamivir phosphate: clinical details
Prescribing considerations
- Base use on the likelihood of influenza, current circulation and susceptibility information; oseltamivir is ineffective against non-influenza pathogens.
- It does not replace seasonal influenza vaccination.
- Assess renal function before prescribing where impairment is possible.
- Seek infection-specialist input for poor clinical response, suspected resistance or complex severe influenza.
Contraindications and cautions
- Hypersensitivity to oseltamivir or an excipient.
- Use particular caution in renal impairment, premature infants and patients developing neuropsychiatric symptoms.
Monitoring
- Clinical response and progression of respiratory or systemic illness
- Renal function when clinically relevant
- New behavioural, cognitive or neurological changes, particularly in children and adolescents
- Repeated vomiting or inability to retain oral treatment
- Resistance where influenza persists or worsens, especially in immunosuppression
Clinical pharmacology
Oseltamivir phosphate is an orally absorbed prodrug converted by esterases to oseltamivir carboxylate, a selective influenza A and B neuraminidase inhibitor. The active metabolite has low protein binding and is eliminated by renal filtration and tubular secretion.
Formulation and product differences
- The selected product is a hard capsule containing oseltamivir phosphate.
- A commercially manufactured oral suspension is preferred for patients unable to swallow capsules or requiring smaller measured quantities.
- The selected capsule contains a small amount of ethanol originating from its printing ink.
oseltamivir phosphate preparations and strengths
Capsule
Route: Oral
Strengths: 30 mg, 45 mg, 75 mg
oseltamivir phosphate interactions
Clinically significant interactions are generally uncommon, but important examples include:
Probenecid
Increases exposure to the active metabolite, although adjustment is not normally required when renal function is normal.
Methotrexate, chlorpropamide or phenylbutazone
Use caution because competition for renal tubular secretion may be important for medicines with a narrow therapeutic margin.
Live attenuated influenza vaccine
Influenza antivirals may reduce the vaccine's effectiveness, so administration should be coordinated with the prescriber or vaccinator.
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.