Chemical formula: C₁₆H₂₈N₂O₄ Molecular mass: 312.405 g/mol PubChem compound: 65028
Oseltamivir interacts in the following cases:
Treatment: The recommended oral dose is 75 mg oseltamivir twice daily for 10 days for adults. Treatment should be initiated as soon as possible within the first two days of onset of symptoms of influenza.
Seasonal prophylaxis: Longer duration of seasonal prophylaxis up to 12 weeks has been evaluated in immunocompromised patients.
Dose adjustment is recommended for adults and adolescents (13 to 17 years of age) with moderate or severe renal impairment. Recommended doses are detailed in the table below.
| Creatinine clearance | Recommended dose for treatment |
|---|---|
| >60 (ml/min) | 75 mg twice daily |
| >30 to 60 (ml/min) | 30 mg (suspension or capsules) twice daily |
| >10 to 30 (ml/min) | 30 mg (suspension or capsules) once daily |
| ≤10 (ml/min) | Not recommended (no data available) |
| Haemodialysis patients | 30 mg after each haemodialysis session |
| Peritoneal dialysis patients* | 30 mg (suspension or capsules) single dose |
* Data derived from studies in continuous ambulatory peritoneal dialysis (CAPD) patients; the clearance of oseltamivir carboxylate is expected to be higher when automated peritoneal dialysis (APD) mode is used. Treatment mode can be switched from APD to CAPD if considered necessary by a nephrologist.
Dose adjustment is recommended for adults and adolescents (13 to 17 years of age) with moderate or severe renal impairment as detailed in the table below.
| Creatinine clearance | Recommended dose for prevention |
|---|---|
| >60 (ml/min) | 75 mg once daily |
| >30 to 60 (ml/min) | 30 mg (suspension or capsules) once daily |
| >10 to 30 (ml/min) | 30 mg (suspension or capsules) every second day |
| ≤10 (ml/min) | Not recommended (no data available) |
| Haemodialysis patients | 30 mg after every second haemodialysis session |
| Peritoneal dialysis patients* | 30 mg (suspension or capsules) once weekly |
* Data derived from studies in continuous ambulatory peritoneal dialysis (CAPD) patients; the clearance of oseltamivir carboxylate is expected to be higher when automated peritoneal dialysis (APD) mode is used. Treatment mode can be switched from APD to CAPD if considered necessary by a nephrologist.
There is insufficient clinical data available in infants and children (12 years of age and younger) with renal impairment to be able to make any dosing recommendation.
No dose adjustment is required when co-administering with probenecid in patients with normal renal function. Co-administration of probenecid, a potent inhibitor of the anionic pathway of renal tubular secretion, results in an approximate 2-fold increase in exposure to the active metabolite of oseltamivir.
Influenza is associated with adverse pregnancy and foetal outcomes, with a risk of major congenital malformations, including congenital heart defects. A large amount of data on oseltamivir exposure of pregnant women from post-marketing reports and observational studies (more than 1000 exposed outcomes during the first trimester) indicate no malformative nor feto/neonatal toxicity by oseltamivir.
However, in one observational study, while the overall malformation risk was not increased, the results for major congenital heart defects diagnosed within 12 months of birth were not conclusive. In this study, the rate of major congenital heart defects following oseltamivir exposure during the first trimester was 1.76% (7 infants out of 397 pregnancies) compared to 1.01% in unexposed pregnancies from the general population (Odds Ratio 1.75, 95% Confidence Interval 0.51 to 5.98). The clinical significance of this finding is not clear, as the study had limited power. Additionally, this study was too small to reliably assess individual types of major malformations; moreover women exposed to oseltamivir and women unexposed could not be made fully comparable, in particular whether or not they had influenza.
Animal studies do not indicate reproductive toxicity.
The use of oseltamivir may be considered during pregnancy if necessary and after considering the available safety and benefit information, and the pathogenicity of the circulating influenza virus strain.
In lactating rats, oseltamivir and the active metabolite are excreted in milk. Very limited information is available on children breast-fed by mothers taking oseltamivir and on excretion of oseltamivir in breast milk. Limited data demonstrated that oseltamivir and the active metabolite were detected in breast milk, however the levels were low, which would result in a subtherapeutic dose to the infant. Considering this information, the pathogenicity of the circulating influenza virus strain and the underlying condition of the breastfeeding woman, administration of oseltamivir may be considered, where there are clear potential benefits to breastfeeding mothers.
Based on preclinical data, there is no evidence that oseltamivir has an effect on male or female fertility.
Oseltamivir has no influence on the ability to drive and use machines.
The overall safety profile of oseltamivir is based on data from 6049 adult/adolescent and 1473 paediatric patients treated with oseltamivir or placebo for influenza, and on data from 3990 adult/adolescent and 253 paediatric patients receiving oseltamivir or placebo/no treatment for the prophylaxis of influenza in clinical trials. In addition, 199 immunocompromised adult patients received oseltamivir for the treatment of influenza and 475 immunocompromised patients (including 18 children, of these 10 oseltamivir and 8 placebo) received oseltamivir or placebo for the prophylaxis of influenza.
In adults/adolescents, the most commonly reported adverse reactions (ARs) were nausea and vomiting in the treatment studies, and nausea in the prevention studies. The majority of these ARs were reported on a single occasion on either the first or second treatment day and resolved spontaneously within 1-2 days. In children, the most commonly reported adverse reaction was vomiting. In the majority of patients, these ARs did not lead to discontinuation of oseltamivir.
The following serious adverse reactions have been rarely reported since oseltamivir has been marketed: Anaphylactic and anaphylactoid reactions, hepatic disorders (fulminant hepatitis, hepatic function disorder and jaundice), angioneurotic oedema, Stevens-Johnson syndrome and toxic epidermal necrolysis, gastrointestinal bleeding and neuropsychiatric disorders.
The ARs listed below fall into the following categories: Very common (≥1/10), common (≥1/100 to <1/10), uncommon (≥1/1,000 to <1/100), rare (≥1/10,000 to <1/1,000), and very rare (<1/10,000). ARs are added to the appropriate category according to the pooled analysis from clinical studies.
In adult/adolescent treatment and prevention studies, ARs that occurred the most frequently at the recommended dose (75 mg bid for 5 days for treatment and 75 mg od for up to 6 weeks for prophylaxis) are shown in the list below.
The safety profile reported in subjects who received the recommended dose of oseltamivir for prophylaxis (75 mg once daily for up to 6 weeks) was qualitatively similar to that seen in the treatment studies, despite a longer duration of dosing in the prophylaxis studies.
Adverse reactions in studies investigating oseltamivir for treatment and prevention of influenza in adults and adolescents or through post-marketing surveillance:
Common: Bronchitis, Herpes simplex, Nasopharyngitis, Upper respiratory tract infections, Sinusitis
Rare: Thrombocytopenia
Uncommon: Hypersensitivity reaction
Rare: Anaphylactic reactions, Anaphylactoid reactions
Rare: Agitation, Abnormal behaviour, Anxiety, Confusion, Delusions, Delirium, Hallucination, Nightmares, Self-injury
Very common: Headache
Common: Insomnia
Uncommon: Altered level of consciousness, Convulsion
Rare: Visual disturbance
Uncommon: Cardiac arrhythmia
Common: Cough, Sore throat, Rhinorrhea
Very common: Nausea
Common: Vomiting Abdominal pain (incl. upper abdominal pain), Dyspepsia
Rare: Gastrointestinal bleedings, Haemorrhagic colitis
Uncommon: Elevated liver enzymes
Rare: Fulminant hepatitis, Hepatic failure, Hepatitis
Uncommon: Eczema, Dermatitis, Rash, Urticaria
Rare: Angioneurotic oedema, Erythema multiforme, Stevens-Johnson syndrome, Toxic epidermal necrolysis
Common: Pain Dizziness (incl. vertigo), Fatigue, Pyrexia, Pain in limb
A total of 1473 children (including otherwise healthy children aged 1-12 years old and asthmatic children aged 6-12 years old) participated in clinical studies of oseltamivir given for the treatment of influenza. Of those, 851 children received treatment with oseltamivir suspension. A total of 158 children received the recommended dose of oseltamivir once daily in a post-exposure prophylaxis study in households (n=99), a 6-week paediatric seasonal prophylaxis study (n=49) and a 12-week paediatric seasonal prophylaxis study in immunocompromised subjects (n=10).
The following list shows the most frequently reported ARs from paediatric clinical trials.
Adverse reactions in studies investigating oseltamivir for treatment and prevention of influenza in children (age/weight-based dosing [30 mg to 75 mg o.d.]):
Common: Otitis media
Common: Headache
Common: Conjunctivitis (including red eyes, eye discharge and eye pain)
Common: Earache
Uncommon: Tympanic membrane disorder
Very common: Cough, Nasal congestion
Common: Rhinorrhoea
Very common: Vomiting
Common: Abdominal pain (incl. upper abdominal pain), Dyspepsia, Nausea
Uncommon: Dermatitis (including allergic and atopic dermatitis)
Influenza can be associated with a variety of neurologic and behavioural symptoms which can include events such as hallucinations, delirium, and abnormal behaviour, in some cases resulting in fatal outcomes. These events may occur in the setting of encephalitis or encephalopathy but can occur without obvious severe disease.
In patients with influenza who were receiving oseltamivir, there have been postmarketing reports of convulsions and delirium (including symptoms such as altered level of consciousness, confusion, abnormal behaviour, delusions, hallucinations, agitation, anxiety, nightmares), in a very few cases resulting in self-injury or fatal outcomes. These events were reported primarily among paediatric and adolescent patients and often had an abrupt onset and rapid resolution. The contribution of oseltamivir to those events is unknown. Such neuropsychiatric events have also been reported in patients with influenza who were not taking oseltamivir.
Hepato-biliary system disorders, including hepatitis and elevated liver enzymes in patients with influenza-like illness. These cases include fatal fulminant hepatitis/hepatic failure.
In two studies to characterise the pharmacokinetics, pharmacodynamics and safety profile of oseltamivir therapy in 135 influenza infected children less than one year of age, the safety profile was similar among age cohorts with vomiting, diarrohea and diaper rash being the most frequently reported adverse events. Insufficient data are available for infants who have a post-conceptual age of less than 36 weeks.
Safety information available on oseltamivir administered for treatment of influenza in infants less than one year of age from prospective and retrospective observational studies (comprising together more than 2,400 infants of that age class), epidemiological databases research and postmarketing reports suggest that the safety profile in infants less than one year of age is similar to the established safety profile of children aged one year and older.
The population included in the influenza treatment studies is comprised of otherwise healthy adults/adolescents and patients “at risk” (patients at higher risk of developing complications associated with influenza, e.g. older people and patients with chronic cardiac or respiratory disease). In general, the safety profile in the patients “at risk” was qualitatively similar to that in otherwise healthy adults/adolescents.
In a double blind study for the treatment of influenza, a total of 199 adult immunocompromised patients (evaluable for safety) were randomized to receive oseltamivir for 10 days: 98 patients received the standard dose (75 mg twice daily) and 101 patients received the double dose (150 mg twice daily). The safety profile of oseltamivir observed in this study was consistent with that observed in previous clinical trials where oseltamivir was administered for treatment of influenza in non-immunocompromised patients (otherwise healthy patients or “at risk” patients [i.e. those with respiratory and/or cardiac co-morbidities]). The percentage of patients reporting adverse events was lower in the standard dose group compared to the double dose group (49.0% vs 59.4%, respectively).
In a 12-week prophylaxis study in 475 immunocompromised patients, including 18 children 1 to 12 years of age and older, the safety profile in the 238 patients who received oseltamivir was consistent with that previously observed in oseltamivir prophylaxis clinical studies.
In general, the adverse reaction profile in children with pre-existing bronchial asthma was qualitatively similar to that of otherwise healthy children.
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