oseltamivir: prescribing and clinical use
Focused clinical detail for use alongside current product information, local policy and patient-specific assessment.
oseltamivir: clinical details
Prescribing considerations
- Confirm influenza is clinically or epidemiologically plausible; oseltamivir has no established efficacy against non-influenza illnesses.
- Consider circulating-virus susceptibility and seek infection or virology advice for poor response, suspected resistance, critical illness or substantial immunosuppression.
- Assess renal function where impairment is possible.
- Evidence is insufficient to guide routine use in premature infants below 36 weeks post-conceptual age.
Contraindications and cautions
- Hypersensitivity to oseltamivir or a formulation excipient.
- The oral suspension contains sorbitol and must not be used in hereditary fructose intolerance.
Monitoring
- Monitor for behavioural or neuropsychiatric changes, particularly in children and adolescents.
- Review clinical response in severe or immunocompromised illness and investigate alternative diagnoses or antiviral resistance where appropriate.
- Monitor for serious skin, allergic, hepatic or gastrointestinal reactions when clinically indicated.
Clinical pharmacology
Oseltamivir is an orally absorbed prodrug converted mainly by hepatic esterases to oseltamivir carboxylate. The active metabolite inhibits influenza A and B neuraminidase and is eliminated predominantly by the kidneys; cytochrome P450-mediated interactions are unlikely.
Formulation and product differences
- Capsules and reconstituted oral suspension are bioequivalent options.
- The suspension should preferably be reconstituted by a pharmacist, shaken before use and measured with its supplied oral dispenser.
- The reconstituted suspension contains sorbitol and sodium benzoate; sodium benzoate may increase jaundice in newborn babies.
- When a suitable liquid product is unavailable, capsule contents may be mixed with a small amount of sweet food using product-specific instructions.
oseltamivir preparations and strengths
Capsule
Route: Oral
Strengths: 30 mg, 45 mg, 75 mg
Oral suspension
Route: Oral
Strengths: 6 mg/mL
oseltamivir interactions
Clinically significant interactions are generally unlikely, but relevant examples include:
Probenecid
Increases exposure to oseltamivir's active metabolite; consider the clinical context and renal function.
Renally secreted medicines with a narrow therapeutic margin, including methotrexate, chlorpropamide and phenylbutazone
Use with caution because competition for renal tubular secretion may alter exposure.
Live attenuated influenza vaccine given as a nasal spray
Influenza antivirals may reduce vaccine effectiveness, so administration timing should be coordinated with a clinician or pharmacist.
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.