Oseltamivir

Treatment: acute uncomplicated influenza A/B at age ≥2 weeks, with symptoms ≤48 hours. Prophylaxis: age ≥1 year. Oseltamivir does not replace annual vaccination, treat other pathogens or establish prevention of bacterial complications; resistance patterns can alter benefit. ESRD without dialysis is not recommended.

CDC recommends prompt treatment for hospitalized, severe/progressive or high-risk influenza, including later presentation; do not await confirmation in priority patients. This extends beyond the uncomplicated ≤48-hour label.

For normal renal function: age ≥13, treatment 75 mg twice daily for 5 days; prophylaxis 75 mg daily for at least 10 days after close contact, up to 6 weeks in a community outbreak or up to 12 weeks in immunocompromised patients. Start labeled treatment within 48 hours of symptoms and exposure prophylaxis within 48 hours of contact. Pediatric treatment is 5 days; labeled pediatric exposure prophylaxis 10 days.

Guideline, not FDA approval: term infants <14 days may receive treatment, 3 mg/kg twice daily for 5 days. CDC cites AAP’s 9–11-month treatment dose of 3.5 mg/kg twice daily. Premature-infant treatment uses postmenstrual age: <38 weeks, 1 mg/kg; 38–40 weeks, 1.5 mg/kg; >40 weeks, 3 mg/kg, each twice daily. Prophylaxis ages 3 months to <1 year: 3 mg/kg daily; under 3 months only in critical circumstances. CDC exposure prophylaxis: 7 days after last exposure; institutional outbreaks: ≥2 weeks and through 1 week after the last case. Longer severe-influenza treatment needs specialist assessment.

This is the FDA adult table; pediatric renal dosing is not established here. Use creatinine clearance and actual dialysis modality, not an automatic eGFR substitution. Prophylaxis duration follows the selected clinical plan.

CDC specifies CAPD treatment after an exchange; an initial hemodialysis dose may precede dialysis, with the postdialysis dose still given. Pediatric renal impairment needs specialist dosing.

Take with or without food; food can improve tolerance. Shake liquid before each use and use a suitable oral mL dispenser, especially for small infant doses. Take a missed dose when remembered unless the next is within 2 hours; skip then and do not double. If directed, the prescribed capsule dose may be opened into a small amount of a listed sweetened liquid and the entire mixture given; do not estimate a fraction of capsule powder.

Commercial powder: pharmacist adds 55 mL water and shakes 15 seconds to yield usable 60 mL at 6 mg/mL. If commercial suspension and appropriate capsule strengths are unavailable, only a pharmacist should use the complete section 2.6 emergency protocol from 75 mg capsules, specified vehicle and PET/glass container. Emergency preparation is also 6 mg/mL but has different storage limits. No home-compounding or injectable regimen is supplied.

Known serious hypersensitivity to oseltamivir or a product component. Serious allergic and severe skin reactions have been reported. ESRD without dialysis is a separate not-recommended population, not the label’s formal contraindication.

Selected current oseltamivir labels have no boxed warning. Serious skin/allergic reactions, behavioral events and suspension fructose-related precautions remain important.

Nausea, vomiting and headache are common; vomiting is prominent in pediatric trials. Infants also had diarrhea and diaper rash. Rare postmarketing reports include severe allergy/skin reactions, gastrointestinal bleeding, hepatitis, arrhythmia, seizure and behavioral changes; incidence/causality cannot be inferred from reports. For overdose contact medical/poison-center services; reported effects generally resemble therapeutic adverse reactions, with many reports asymptomatic.

Avoid intranasal live attenuated influenza vaccine within 2 weeks before or 48 hours after oseltamivir unless medically indicated; inactivated vaccine may be given at any time. Probenecid increases active-metabolite exposure about twofold, but the label requires no adjustment for that combination. No clinically significant interaction requiring adjustment was observed with listed agents including amoxicillin, acetaminophen, antacids and warfarin. This does not remove their independent risks or pediatric aspirin restrictions.

Influenza poses increased pregnancy risk. Available epidemiologic data do not suggest increased birth-defect risk with oseltamivir, but are insufficient to establish absence of risk. Label PK data do not support a routine pregnancy dose adjustment. Limited milk data show low oseltamivir/active-metabolite levels, unlikely to cause infant toxicity; consider maternal need and breastfeeding benefits, with milk-production effects unknown.

FDA treatment begins at 2 weeks and prophylaxis at 1 year; neonatal/off-label recommendations are identified in dosing. No routine age-only adjustment is needed in older adults, but renal function determines dosing. Mild/moderate hepatic impairment needs no adjustment; severe impairment is unstudied. Renal impairment increases active-metabolite exposure and needs the adult regimen above; dialysis/non-dialysis status is essential.

The selected label did not establish symptom-alleviation efficacy in chronic cardiac/respiratory disease trials, or treatment/prophylaxis efficacy in immunocompromised patients; prophylaxis safety was demonstrated up to 12 weeks. These evidence limitations do not negate separately stated CDC priority-treatment guidance. Severe/prolonged illness needs individualized duration and susceptibility assessment.

Hepatic esterases convert the prodrug to oseltamivir carboxylate, which inhibits influenza A/B neuraminidase and impairs release of viral particles. At least 75% of an oral dose reaches circulation as active metabolite. Active-metabolite protein binding is about 3%, half-life 6–10 hours and elimination >99% renal, including tubular secretion. Parent half-life is 1–3 hours. Neither form is a CYP substrate/inhibitor; food has no clinically significant exposure effect. Resistance can reduce antiviral activity.

Review symptom/exposure onset, diagnosis, dose, weight and renal/dialysis status. Monitor ability to take oral medicine, vomiting, hydration, skin/allergy symptoms, behavior and signs of bacterial infection or deterioration. Follow renal function when it may change. Lack of response needs clinical reassessment rather than automatic double dosing; no routine serum drug-level monitoring is prescribed.

Complete the prescribed treatment/prevention course and keep the schedules distinct. Use food for tolerance if helpful; measure liquid in mL and shake first. Do not double missed doses or switch concentrations. Seek urgent help for breathing/swelling reactions, blistering rash, confusion or dangerous behavior. Annual influenza vaccination remains important. Children/neonates, dialysis and hereditary fructose intolerance need the prescriber/pharmacist’s exact plan.

Tamiflu 75 mg capsule: grey/light-yellow hard gelatin capsule marked ROCHE and 75 mg; ten-capsule blister NDC 0004-0800-85. This is product identity, not local inventory.

Selected labels describe 30, 45 and 75 mg oral capsules and commercial 6 mg/mL suspension after constitution. Current FDA: branded Tamiflu 75 mg and 6 mg/mL are Prescription; branded 30/45 mg capsules and older 12 mg/mL suspension are Discontinued. Selected Strides generic 30/45/75 mg capsules remain Prescription. Do not infer discontinuation of all generic pediatric capsule strengths or a current IV formulation.

Capsules and unconstituted powder: 25°C, excursions 15–30°C. Commercial 6 mg/mL liquid: 17 days refrigerated at 2–8°C or 10 days at 25°C; do not freeze. Pharmacist emergency capsule-derived preparation: 5 weeks refrigerated or 5 days at 25°C in the specified PET/glass bottle. Follow the dated pharmacy label and discard remaining emergency liquid after the course; do not transfer commercial storage limits to compounded supply.