Hard capsule - 30 mg, 45 mg and 75 mg; Powder for oral suspension - 6 mg/mL
Note: Tamiflu 30 mg and 45 mg capsules are currently not available.
Oseltamivir phosphate. 30 mg capsules contain 39.4 mg oseltamivir phosphate equivalent to 30 mg of oseltamivir. 45 mg capsules contain 59.1 mg oseltamivir phosphate equivalent to 45 mg of oseltamivir. 75 mg capsules contain 98.5 mg oseltamivir phosphate equivalent to 75 mg of oseltamivir. 6 mg/mL powder for oral suspension contains 0.5122 g oseltamivir phosphate, which when constituted with 55 mL of water makes 65 mL of 6 mg/mL oseltamivir.
Capsules
Capsule fill:
Povidone K30, pre-gelatinised starch, croscarmellose sodium, talc, sodium stearyl fumarate.
Capsule shell:
Black iron oxide, red iron oxide, yellow iron oxide, titanium dioxide, gelatin.
Printing ink:
Dehydrated alcohol, shellac, n-butyl alcohol, titanium dioxide, FDC Blue 2, SDA-3A alcohol.
Powder for oral suspension
Sorbitol, titanium dioxide, sodium benzoate, xanthan gum, sodium dihydrogen citrate (monosodium citrate), saccharin sodium, flavour - PERMASEAL 142000 Tutti Frutti.
Capsules: 30 mg hard gelatin capsule consists of a light yellow opaque body bearing the imprint "ROCHE" and a light yellow opaque cap bearing the imprint "30 mg". Imprints are blue.
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45 mg hard gelatin capsule consists of a grey opaque body bearing the imprint "ROCHE" and a grey opaque cap bearing the imprint "45 mg". Imprints are blue. 75 mg hard gelatin capsule consists of a grey opaque body bearing the imprint "ROCHE" and a light yellow opaque cap bearing the imprint "75 mg". Imprints are blue.
Powder for oral suspension:
The powder is a granulate or clumped granulate with a white to light yellow colour.
Tamiflu is indicated for the treatment of influenza in adults and children 1 year of age (see Special Warnings and Special Precautions for Use and Preclinical Safety). Tamiflu is indicated for the prophylaxis of influenza in adults and children 1 years of age. Vaccination is the preferred method of routine prophylaxis against infection with influenza virus.
Tamiflu may be taken with or without food (see Pharmacokinetic Properties). However, Tamiflu taken with food may enhance tolerability in some patients.
Treatment of influenza
Treatment should begin within the first or second day of onset of symptoms of influenza.
Adults and adolescents
The recommended oral dose of Tamiflu for adults and adolescents 13 years is 75 mg twice daily, for 5 days. Adults and adolescents 13 years of age can take Tamiflu capsules. Patients unable to swallow capsules may receive the appropriate dose of Tamiflu oral suspension or home-prepared or pharmacy-compounded Tamiflu capsules (see Patients unable to swallow capsules) to achieve a 75 mg dose.
Infants and Children >= 1 to < 13 years of age
The recommended weight adjusted dosing regimens of Tamiflu for children 1 year of age are:
| Body weight | Recommended dose for 5 days | Volume of 6 mg/mL oral suspension |
| 15 kg | 30 mg twice daily | 5.0 mL twice daily |
| > 15 to 23 kg | 45 mg twice daily | 7.5 mL twice daily |
| > 23 kg to 40 kg | 60 mg twice daily | 10.0 mL twice daily |
| > 40 kg | 75 mg twice daily | 12.5 mL twice daily |
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Infants and children >= 1 year old may receive the required Tamiflu dose in the form of capsules. Patients unable to swallow capsules may receive the appropriate dose of Tamiflu oral suspension or home-prepared or pharmacy-compounded Tamiflu capsules (see Patients unable to swallow capsules).
For the 6 mg/mL powder for oral suspension
a 10 mL oral dosing dispenser, with 0.5 mL graduations is provided. Each 30 mg dose is equivalent to 5.0 mL of suspension. Each 45 mg dose is equivalent to
7.5 mL of suspension. It is recommended that patients use this dispenser. It is recommended that Tamiflu powder for oral suspension be reconstituted by a pharmacist prior to dispensing to the patient (see Special Remarks, Handling and disposal).
Prophylaxis of influenza
Adults and adolescents
The recommended oral dose of Tamiflu for adults and adolescents 13 years for prophylaxis of influenza following close contact with an infected individual is 75 mg once daily for 10 days. Adults and adolescents 13 years of age can take capsules. Therapy should begin within two days of exposure. The recommended dose for prophylaxis during a community outbreak of influenza is 75 mg once daily. Safety and efficacy have been demonstrated for up to six weeks. The duration of protection lasts for as long as dosing is continued. Adults and adolescents 13 years of age and older who are unable to swallow capsules may receive the appropriate dose of Tamiflu oral suspension or home-prepared or pharmacy-compounded Tamiflu capsules (see Patients unable to swallow capsules).
Infants and Children >= 1 to < 13 years of age
The recommended weight-adjusted prophylactic oral dosing regimens of Tamiflu for children 1 year of age are:
| Body weight | Recommended dose for 10 days | Volume of 6 mg/mL oral suspension |
| 15 kg | 30 mg once daily | 5.0 mL once daily |
| > 15 to 23 kg | 45 mg once daily | 7.5 mL once daily |
| > 23 kg to 40kg | 60 mg once daily | 10.0 mL once daily |
| > 40 kg | 75 mg once daily | 12.5 mL once daily |
Infants and children >= 1 year old may receive the required Tamiflu dose in the form of capsules but those who are unable to swallow capsules may receive the appropriate dose of Tamiflu oral suspension or home-prepared or pharmacy-compounded Tamiflu capsules (see Patients unable to swallow capsules).
For the 6 mg/mL powder for oral suspension
a 10 mL oral dosing dispenser, with 0.5 mL graduations is provided. Each 30 mg dose is equivalent to 5.0 mL of suspension. Each 45 mg dose is equivalent to
mL of suspension. It is recommended that patients use this dispenser. It is recommended that Tamiflu powder for oral suspension be reconstituted by a pharmacist prior to dispensing to the patient (see Special Remarks, Handling and disposal).
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When commercially manufactured Tamiflu powder for oral suspension is not readily available, adults, adolescents, children and infants (>= 1 year of age) who are unable to swallow capsules may receive appropriate doses of Tamiflu either prepared at home by caregivers or prepared by a pharmacist.
Home-prepared, extemporaneous preparation of capsules
Adults and adolescents (13 years and older)
Adults and adolescents who are unable to swallow capsules may receive a 75 mg dose of Tamiflu by following the instructions below.
Hold one Tamiflu 75 mg capsule over a small bowl, carefully pull the capsule open and pour the powder into the bowl,
Add a suitable, small amount (1 teaspoon maximum) of sweetened food product such as regular or sugar-free chocolate syrup, honey, light brown or table sugar dissolved in water, dessert toppings, sweetened condensed milk, apple sauce or yogurt to mask the bitter taste of the medication.
Stir the mixture well and give the entire contents to the patient. The mixture must be swallowed immediately after its preparation. If there is some mixture left inside the bowl, rinse the bowl with a small amount of water and have the patient drink this remaining mixture. It is not necessary to administer any undissolved white powder as this is inert material.
Children (1 year and older); 15 mg/mL solution
Children who are unable to swallow capsules and require a dose different to that available in capsule form may receive appropriate doses of Tamiflu by following the instructions below.
Hold one Tamiflu 75 mg capsule over a small bowl, carefully pull the capsule open and pour the powder into the bowl.
Using a graduated syringe, add 5 mL water to the powder. Stir for about two minutes.
Draw up into the syringe the correct amount of mixture from the bowl (see table below). The recommended dose is body weight dependent
Push down on the plunger of the syringe, to empty its entire contents into a second bowl. Discard any unused mixture. | ||
|---|---|---|
| Body weight | Recommended dose | Amount of Tamiflu mixture for one dose (15 mg/mL) |
| <= 15 kg | 30 mg | 2 mL |
| > 15 to 23 kg | 45 mg | 3 mL |
| > 23 kg to 40kg | 60 mg | 4 mL |
| > 40 kg | 75 mg | 5 mL |
Note: This compounding procedure results in a 15 mg/mL mixture, which is different from the commercially available Tamiflu Oral Suspension. In the second bowl, add a suitable, small amount (1 teaspoon maximum) of sweetened food product such as regular or sugar-free chocolate syrup, honey (only for children one year or older), light brown or table sugar dissolved in water, dessert toppings, sweetened condensed milk, apple sauce or yogurt to the mixture to mask the bitter taste of the medication. Stir this mixture well and give the entire contents of the second bowl to the patient. This mixture must be swallowed immediately after its preparation. If there is some mixture left inside the bowl, rinse the bowl with a small amount of water and have the patient drink this remaining mixture.
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Pharmacy-compounded Tamiflu for adults, adolescents, children and infants >= 1 year of age This procedure describes the preparation of a 15 mg/mL suspension, which will provide one patient with enough medication for a 5-day course of treatment or a 10-day course of prophylaxis. The pharmacist may compound a suspension (15 mg/mL) from Tamiflu 75 mg capsules using water containing 0.1% w/v sodium benzoate added as a preservative. First, calculate the total volume needed to be compounded and dispensed to provide a 5-day course of treatment or a 10-day course of prophylaxis for the patient. The total volume of compounded Tamiflu 15 mg/mL suspension required is determined by the weight of the patient according to the recommendation in the table below:
| Body Weight (kg) | Total Volume to Compound per Patient Weight (mL) |
| <= 15 kg | 30 mL |
| > 15 - 23 kg | 40 mL |
| > 23 - 40 kg | 50 mL |
| > 40 kg | 60 mL |
Second, determine the number of capsules and the amount of vehicle (water containing 0.1% w/v sodium benzoate added as a preservative) that is needed to prepare the total volume (calculated from the table above: 30 mL, 40 mL, 50 mL or 60 mL) of compounded Tamiflu 15 mg/mL suspension as shown in the table below:
| Total Volume of Compounded Suspension to be Prepared | Required Number of Tamiflu 75 mg Capsules (mg of oseltamivir) | Required Volume of Vehicle |
| 30 mL | 6 capsules (450 mg) | 29 mL |
| 40 mL | 8 capsules (600 mg) | 38.5 mL |
| 50 mL | 10 capsules (750 mg) | 48 mL |
| 60 mL | 12 capsules (900 mg) | 57 mL |
Third, follow the procedure below for compounding the suspension (15 mg/mL) from Tamiflu capsules:
Carefully separate the capsule body and cap and transfer the contents of the required number of Tamiflu capsules into a clean mortar.
Triturate the granules to a fine powder.
Add one-third (1/3) of the specified amount of vehicle (water containing 0.1% w/v sodium benzoate added as a preservative) and triturate the powder until a uniform suspension is achieved.
Transfer the suspension to an amber glass or amber polyethyleneterephthalate (PET) bottle. A funnel may be used to eliminate any spillage.
Add another one-third (1/3) of the vehicle to the mortar, rinse the pestle and mortar by a triturating motion and transfer the vehicle into the bottle.
Repeat the rinsing (Step 5) with the remainder of the vehicle.
Close the bottle using a child-resistant cap.
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Shake well to completely dissolve the active drug and to ensure homogeneous distribution of the dissolved drug in the resulting suspension. (Note: Undissolved residue may be visible but is comprised of inert ingredients of Tamiflu capsules, which are insoluble. However, the active drug, oseltamivir phosphate, readily dissolves in the specified vehicle and therefore forms a uniform solution.) Put an ancillary label on the bottle indicating "Shake Gently Before Use". Instruct the parent or caregiver that after the patient has completed the full course of therapy any remaining solution must be discarded. It is recommended that this information be provided by affixing an ancillary label to the bottle or adding a statement to the pharmacy label instructions. Place an appropriate expiration date label according to storage condition (see Pharmaceutical Particulars, Stability). Place a pharmacy label on the bottle that includes the patient's name, dosing instructions, use by date, medicine name and any other required information to be in compliance with local pharmacy regulations. Refer to the table below for the proper dosing instructions for pharmacy-compounded 15 mg/mL suspension from Tamiflu capsules for infants and children >= 1 year old.
| Body Weight (kg) | Dose (mg) | Volume per Dose 15 mg/mL | Treatment Dose (for 5 days) | Prophylaxis Dose (for 10 days) |
| <= 15 kg | 30 mg | 2 mL | 2 mL twice daily | 2 mL once daily |
| > 15 - 23 kg | 45 mg | 3 mL | 3 mL twice daily | 3 mL once daily |
| > 23 - 40 kg | 60 mg | 4 mL | 4 mL twice daily | 4 mL once daily |
| > 40 kg | 75 mg | 5 mL | 5 mL twice daily | 5 mL once daily |
Note: This compounding procedure results in a 15 mg/mL suspension, which is different from the commercially availableTamiflu Oral Suspension. Dispense the suspension with a graduated oral syringe for measuring small amounts of suspension. If possible, mark or highlight the graduation corresponding to the appropriate dose (2 mL, 3 mL, 4 mL or 5 mL) on the oral syringe for each patient. The appropriate dose must be mixed by the caregiver with an equal quantity of sweet liquid food, such as sugar water, chocolate syrup, cherry syrup, dessert toppings (like caramel or fudge sauce) to mask the bitter taste.
In adults, no dose adjustment is necessary for patients with creatinine clearance above 60 mL/min. In patients with a creatinine clearance of > 30 - 60 mL/min, it is recommended that the dose be reduced to 30 mg of Tamiflu twice daily for 5 days. In patients with a creatinine clearance of 10 - 30 mL/min, it is recommended that the dose is reduced to 30 mg of Tamiflu once daily for 5 days. In patients undergoing routine haemodialysis, an initial dose of 30 mg of Tamiflu can be administered prior to the start of dialysis if influenza symptoms develop during the 48 hours between dialysis sessions. To maintain plasma concentrations at a therapeutic level, a dose of 30 mg should be administered after every haemodialysis session. For peritoneal dialysis, a dose of 30 mg of Tamiflu administered prior to the start of dialysis followed by further 30 mg doses administered every 5 days is recommended for treatment. (see Pharmacokinetics in special populations ).The pharmacokinetics of oseltamivir have not been studied in patients with end stage renal disease (i.e. creatinine clearance of < 10 mL/min) not undergoing dialysis. Hence, dosing recommendation can not be provided for this group.
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Prophylaxis of influenza
In adults, no dose adjustment is necessary for patients with creatinine clearance above 60 mL/min. In patients with a creatinine clearance of > 30 - 60 mL/min, it is recommended that the dose be reduced to 30 mg of Tamiflu once daily. In patients with creatinine clearance between 10 - 30 mL/min receiving Tamiflu, it is recommended that the dose be reduced to 30 mg every other day. In patients undergoing routine haemodialysis, an initial dose of 30 mg of Tamiflu can be administered prior to the start of dialysis. To maintain plasma concentrations at a therapeutic level, a dose of 30 mg should be administered after every alternate haemodialysis session. For peritoneal dialysis, an initial dose of 30 mg of Tamiflu administered prior to the start of dialysis followed by further 30 mg doses administered every 7 days is recommended for prophylaxis (see Pharmacokinetics in special populations). The pharmacokinetics of oseltamivir have not been studied in patients with end stage renal disease (i.e. creatinine clearance of < 10 mL/min) not undergoing dialysis. Hence, dosing recommendation can not be provided for this group.
Children with renal impairment
There is insufficient clinical data available in children with renal impairment to be able to make any dosing recommendation.
Patients with hepatic impairment
No dose adjustment is required for patients with hepatic dysfunction in the treatment or prophylaxis of influenza (see Pharmacokinetics in special populations). No studies have been carried out in paediatric patients with hepatic impairment.
Immunocompromised patients
Seasonal prophylaxis in immunocompromised patients >= 1 year of age is recommended for 12 weeks. No dose adjustment is necessary.
Use in the elderly
No dose adjustment is required for elderly patients in the treatment or prophylaxis of influenza (see Pharmacokinetics in special populations).
Paediatric use
The safety and efficacy of Tamiflu in children under 1 year has not been established (see Pharmacokinetics in special populations). Tamiflu should not be used in children under 1 year of age (see Preclinical Safety).
Hypersensitivity to oseltamivir phosphate or any component of the product.
Convulsion and delirium like neuropsychiatric events have been reported during Tamiflu administration in patients with influenza, predominately in children and adolescents. In rare cases, these events
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resulted in accidental injury. The contribution of Tamiflu to those events is unknown and these have also been reported in patients with influenza who were not taking Tamiflu (see Post Marketing experience). Patients, especially children and adolescents, should be closely monitored for signs of abnormal behaviour. There is no evidence for efficacy of Tamiflu in any illness caused by agents other than influenza viruses types A and B.
Sorbitol
Tamiflu powder for oral suspension contains sorbitol. For subjects with hereditary fructose intolerance, Tamiflu powder for oral suspension is not recommended. Sorbitol may have a laxative effect or cause diarrhoea. A bottle of 13 g Tamiflu 6 mg/mL powder for oral suspension contains 11.142 g of sorbitol. 30 mg oseltamivir suspension delivers 0.9 g of sorbitol. 45 mg oseltamivir suspension delivers 1.3 g of sorbitol. 60 mg oseltamivir suspension delivers 1.7 g of sorbitol. 75 mg oseltamivir suspension delivers 2.1 g of sorbitol.
Use in Renal Impairment
For dose adjustments in patients with renal impairment refer to the Special dosage instructions and Pharmacokinetics in special populations sections.
Pregnancy - Category B1 In animal reproductive studies in rats and rabbits, no teratogenic effect was observed. Fertility and reproductive toxicity studies have been conducted in rats. There was no evidence of an effect on fertility at any dose of oseltamivir studied. Foetal exposure in rats and rabbits was approximately 15 - 20% of that of the mother. Because animal reproductive studies may not be predictive of human response, and there are no adequate and well-controlled studies in pregnant women, Tamiflu should be used during pregnancy only if the potential benefit justifies the potential risk to the foetus. While no controlled clinical trials have been conducted on the use of Tamiflu in pregnant women, limited data available from post-marketing and retrospective observational surveillance do not indicate direct or indirect harmful effects with respect to pregnancy or embryonal/foetal development.
In lactating rats, oseltamivir and the active metabolite are secreted in milk. Very limited information is available on children breast-fed by mothers taking Tamiflu and on excretion of oseltamivir in breast milk. Limited data demonstrated that oseltamivir and the active metabolite were detected in breast milk at very low levels. Tamiflu should be used in lactating mothers only if the potential benefit for the lactating mother justifies the potential risk of exposure of the medicine to the nursing infant.
The safety and efficacy of Tamiflu in paediatric patients have not been established in children aged less than 1 year of age. Tamiflu should not be used in children under 1 year of age (see Preclinical safety). No studies have been carried out in paediatric patients with hepatic impairment.
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There is insufficient clinical data available in children with renal impairment to be able to make any dosing recommendation.
Elevated liver enzymes have been reported in patients with influenza-like illness receiving oseltamivir.
Direct contact of oseltamivir phosphate with the skin and eyes should be avoided as it is a potential skin sensitiser and eye irritant.
Information derived from pharmacology and pharmacokinetic studies of oseltamivir phosphate suggest that clinically significant interactions with other medicines are unlikely. Oseltamivir phosphate is extensively converted to the active compound by esterases, located predominantly in the liver. Interactions involving competition for esterases have not been extensively reported in the literature. Low protein binding of oseltamivir and the active metabolite do not suggest the probability of displacement interactions.
In vitro
studies demonstrated that neither oseltamivir phosphate nor the active metabolite is a good substrate for P450 mixed-function oxidases or for glucuronyl transferases (see Pharmacokinetic properties). There is no mechanistic basis for an interaction with oral contraceptives.
Cimetidine, a non-specific inhibitor of cytochrome P450 isoforms and competitor for renal tubular secretion of basic or cationic agents has no effect on plasma levels of oseltamivir or its active metabolite. Clinically important interactions involving competition for renal tubular secretion are unlikely due to the known safety margin for most of these medicines, the elimination characteristics of the active metabolite (glomerular filtration and anionic tubular secretion) and the excretion capacity of these pathways. Co-administration of probenecid results in approximate 2-fold increase in exposure to the active metabolite due to a decrease in active tubular secretion in the kidney. However, due to the wide safety margin of the active metabolite, no dose adjustments are required when co-administering with probenecid. Co-administration with amoxicillin does not alter plasma levels of either compound, indicating that competition for the anionic secretion pathway is weak. Co-administration with paracetamol does not alter plasma levels of oseltamivir, its active metabolite, or paracetamol. No pharmacokinetic interactions between oseltamivir or its major metabolite have been observed when co-administering oseltamivir with paracetamol, acetyl-salicylic acid, cimetidine, antacids (magnesium and aluminium hydroxides and calcium carbonates), warfarin, rimantadine or amantadine. In phase III treatment and prophylaxis clinical studies, Tamiflu has been administered with commonly used medicines such as ACE inhibitors (enalapril, captopril), thiazide diuretics (bendrofluazide)
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antibiotics (penicillin, cephalosporin, azithromycin, erythromycin and doxycycline), H2-receptor blockers (ranitidine, cimetidine), beta-blockers (propranolol), xanthines (theophylline), sympathomimetics (pseudoephedrine), opioids (codeine), corticosteroids, inhaled bronchodilators and analgesic agents (aspirin, ibuprofen and paracetamol). No change in adverse event profile or frequency has been observed as a result of co-administration of Tamiflu with these compounds.
Experience from clinical trials
The overall safety profile of Tamiflu is based on data from 2647 adults/adolescents and 858 paediatric patients with influenza, and on data from 1945 adult/adolescent and 148 paediatric patients receiving Tamiflu for the prophylaxis of influenza in clinical trials . In adult/adolescent treatment studies, the most frequently reported adverse drug reactions (ADRs) were nausea, vomiting and headache. The majority of these ADRs were reported on a single occasion, occurred on either the first or second treatment day and resolved spontaneously within 1 - 2 days. In adult/adolescent prophylaxis studies, the most frequently reported ADRs were nausea, vomiting, headache and pain. In children, the most commonly reported ADR was vomiting. In the majority of patients, these events did not lead to discontinuation of Tamiflu.
Treatment and Prophylaxis of Influenza in Adults and Adolescents
In adult/adolescent treatment and prophylaxis studies, ADRs that occurred the most frequently (>= 1%) at the recommended dose (75 mg twice daily for 5 days for treatment and 75 mg once daily for up to 6 weeks for prophylaxis), and whose incidence is at least 1% higher on Tamiflu compared to placebo, are shown in Table 2. The population included in the influenza treatment studies comprised of otherwise healthy adults/adolescents and patients "at risk" (patients at higher risk of developing complications associated with influenza, e.g. elderly patients 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. The safety profile reported in the subjects that received the recommended dose of Tamiflu for prophylaxis (75 mg once daily for up to 6 weeks) was qualitatively similar to that seen in the treatment studies (see Table 1), despite a longer duration of dosing in the prophylaxis studies.
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Table 1: Percentage of patients with ADRs that occurred in >= 1% of the adults and adolescents in the oseltamivir group in studies investigating Tamiflu for treatment or prophylaxis of influenza (difference to placebo >= 1%) | |||||
|---|---|---|---|---|---|
| System Organ Class Adverse Drug Reaction | Treatment Studies | Prophylaxis | Frequency category a | ||
| Tamiflu (75 mg twice daily) n = 2647 | Placebo n = 1977 | Tamiflu (75 mg twice daily) n = 1945 | Placebo n = 1588 | ||
| Gastrointestinal | 10% | 6% | 8% | 4% | very common |
| Disorders | |||||
| Nausea | |||||
| Vomiting | 8% | 3% | 2% | 1% | common |
| Neurological and Nervous System Disorders Headache | 2% | 1% | 17% | 16% | very common |
| General Disorders Pain | < 1% | < 1% | 4% | 3% | common |
a
Frequency category is reported only for the Tamiflu group. Standard names to describe each of the frequency categories follow this convention: very common (>=1/10); common (>=1/100 to < 1/10).
Adverse events reported in >= 1% of the adults and adolescents taking Tamiflu in the treatment studies (n = 2647) and in the prophylaxis studies (n = 1945), which occurred more frequently in the patients on placebo or where the difference between the Tamiflu and placebo arm was < 1%, were the following:
Gastrointestinal Disorders (Tamiflu versus placebo)
Treatment: diarrhoea (6% vs. 7%), abdominal pain (incl. upper abdominal pain, 2% vs. 3%)
Prophylaxis: diarrhoea (3% vs. 4%), upper abdominal pain (2% vs. 2%), dyspepsia
(1% vs. 1%)
Infections and Infestations (Tamilfu vs. placebo)
Treatment: bronchitis (3% vs. 4%), sinusitis (1% vs. 1%), herpes simplex (1% vs. 1%) Prophylaxis: nasopharyngitis (4% vs. 4%), upper respiratory tract infections (3% vs. 3%), influenza (2% vs. 3%)
General Disorders (Tamiflu vs. placebo)
Treatment: dizziness (incl. vertigo, 2% vs. 3%), Prophylaxis: fatigue (7% vs. 7%), pyrexia (2% vs. 2%), influenza like illness (1% vs. 2%), dizziness (1% vs. 1%), pain in limb (1% vs. <1%)
Neurological and Nervous System Disorders (Tamiflu vs. placebo)
Treatment: insomnia (1% vs. <1%) Prophylaxis: insomnia (1% vs. <1%)
Respiratory, Thoracic and Mediastinal Disorders (Tamiflu vs. placebo)
Treatment: cough (2% vs. 2%), nasal congestion (1% vs. 1%) Prophylaxis: nasal congestion (7% vs. 7%), sore throat (5% vs. 5%), cough (5% vs. 6%), rhinorrhea (1% vs. 1%)
Musculoskeletal, Connective Tissue and Bone Disorders (Tamifly vs. placebo)
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Prophylaxis: back pain (2% vs. 3%), arthralgia (1% vs. 2%), myalgia (1% vs. 1%)
Disorders of the Reproductive System and Breast (Tamiflu vs. placebo)
Prophylaxis: dysmenorrhoea (3% vs. 3%)
Treatment and Prophylaxis of Influenza in Elderly
There were no clinically relevant differences in the safety profile of the 942 elderly subjects, who received Tamiflu or placebo, compared with the younger population (aged up to 65 years).
Prophylaxis of Influenza in Immunocompromised Patients
A 12-week prophylaxis study in 475 immunocompromised patients, including 18 children 1 - 12 years old, showed that the safety profile in the 238 subjects receiving Tamiflu was consistent with that previously observed in Tamiflu prophylaxis clinical trials.
Treatment and Prophylaxis of Influenza in Paediatrics
A total of 1480 paediatric patients (including 698 otherwise healthy children aged 1 - 12 years old and asthmatic children aged 6 - 12 years old) participated in clinical studies investigating the use of Tamiflu in the treatment of influenza. A total of 858 paediatric patients received treatment with Tamiflu suspension. The ADRs that occurred in >= 1% of children aged 1 - 12 years receiving Tamiflu in the clinical trials for treatment of naturally acquired influenza (n = 858), and whose incidence is at least 1% higher on Tamiflu compared to placebo (n = 622), is vomiting (16% on oseltamivir vs. 8% on placebo). Amongst the 148 children who received the recommended dose of Tamilfu once daily in a post-exposure prophylaxis study in households (n = 99), and in a separate 6-week paediatric prophylaxis study (n = 49), vomiting was the most frequent ADR (8% on Tamiflu vs. 2% in the no prophylaxis group). Tamiflu was well tolerated in these studies and the adverse events noted were consistent with those previously observed in paediatric treatment studies. Adverse events reported in >= 1% of the children taking Tamiflu in the treatment studies (n = 858) or >= 5% of the children in the prophylaxis studies (n = 148), which occurred more frequently in the children on placebo/no prophylaxis or where the difference between the oseltamivir and placebo/no prophylaxis arm was < 1%, were the following:
Gastrointestinal Disorders (Tamiflu versus placebo)
Treatment: diarrhoea (9% vs. 9%), nausea (4% vs. 4%), abdominal pain (incl. upper abdominal pain, 3% vs. 3%)
Infections and Infestations (Tamiflu vs. placebo)
Treatment: otitis media (5% vs. 8%), bronchitis (2% vs. 3%), pneumonia (1% vs. 3%), sinusitis (1% vs. 2%)
Respiratory, Thoracic and Mediastinal Disorders (Tamiflu vs. placebo)
Treatment: asthma (including aggravated asthma, 3% vs. 4%), epistaxis (2% vs. 2%) Prophylaxis: cough (12% vs. 26%), nasal congestion (11% vs. 20%)
Skin and Subcutaneous Tissue Disorders (Tamiflu vs. placebo)
Treatment: dermatitis (including allergic and atopic dermatitis, 1% vs. 2%)
Disorders of Ear and Labyrinth (Tamiflu vs. placebo)
Treatment: earache (1% vs. < 1%)
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Disorders of the Eye (Tamiflu vs. placebo)
Treatment: conjunctivitis (including red eyes, eye discharge and eye pain, 1% vs. < 1%)
Additional adverse events reported from paediatric treatment studies, which previously qualified to be presented above, however in larger datasets did not fulfill the criteria for inclusion in previous sections anymore, are given below:
Disorders of Blood and Lymphatic system (Tamiflu vs. placebo)
Treatment: lymphadenopathy (< 1% vs. 1%)
Disorders of Ear and Labyrinth (Tamiflu vs. placebo)
Treatment: tympanic membrane disorder (< 1% vs. 1%)
Post-Marketing Experience
The following adverse events have been identified during post-marketing use of Tamiflu. Because these events are reported voluntarily from a population of uncertain size, it is not possible to reliably estimate their frequency and/or establish a causal relationship to Tamiflu exposure.
Skin and subcutaneous tissue disorders:
hypersensitivity reactions such as allergic skin reactions including dermatitis, rash, eczema and urticaria, erythema multiforme, allergy, anaphylactic/anaphylactoid reactions, face oedema, Stevens-Johnson-Syndrome and toxic epidermal necrolysis have been reported.
Hepatobiliary disorders:
hepatitis and elevated liver enzymes have been reported in patients with influenza-like illness receiving oseltamivir.
Psychiatric disorders/Nervous system disorders:
convulsion and delirium (including symptoms such as altered level of consciousness, confusion, abnormal behaviour, delusions, hallucinations, agitation, anxiety and nightmares) have been reported during Tamiflu administration in patients with influenza, predominately in children and adolescents. These events often had an abrupt onset and rapid resolution. In rare cases, these events resulted in accidental injury, and some resulted in a fatal outcome, however, the contribution of Tamiflu to those events is unknown. Such neuropsychiatric events have also been reported in patients with influenza who were not taking Tamiflu. Three separate large epidemiological studies confirmed that influenza-infected patients receiving Tamiflu are at no higher risk of developing neuropsychiatric events in comparison to influenza-infected patients not receiving antivirals.
Patients with influenza should be closely monitored for signs of abnormal behaviour throughout the treatment period.
Gastrointestinal disorders:
gastrointestinal bleeding was observed after the use of Tamiflu. In particular, haemorrhagic colitis was reported and subsided when the course of influenza abated or treatment with Tamiflu was interrupted.
Blood and lymphatic system disorders
: thrombocytopenia
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Pharmacological Properties and Effects
Pharmacodynamic Properties
Oseltamivir phosphate is a pro-drug of oseltamivir carboxylate, a potent and selective inhibitor of influenza virus neuraminidase enzymes. Viral neuraminidase is important both for viral entry into uninfected cells and for the release of recently formed virus particles from infected cells, and the further spread of infectious virus. Oseltamivir carboxylate inhibits the neuraminidases of influenza viruses of both types A and B. Concentrations of oseltamivir carboxylate required to inhibit the enzyme activity by 50% (IC50) are in the low nanomolar range. Oseltamivir carboxylate also inhibits influenza virus infection and replication in-vitro and inhibits influenza virus replication and pathogenicity in-vivo. Oseltamivir carboxylate reduces shedding of both influenza A and B virus by inhibiting the release of infectious virus from infected cells.
Clinical efficacy of Tamiflu has been demonstrated in human experimental infection studies and phase III studies in naturally occurring influenza. In studies in naturally acquired and experimental influenza, treatment with Tamiflu did not impair normal humoral antibody response to infection. Antibody response to inactivated vaccine is not expected to be affected by treatment with Tamiflu.
Trials in naturally occurring influenza
In phase III clinical trials conducted in the 1997 - 1998 Northern Hemisphere influenza season, patients were treated with Tamiflu for up to 40 hours after reported onset of symptoms. In these studies, 97% of patients were infected with influenza A and 3% with influenza B. Tamiflu treatment significantly reduced the duration of clinically relevant signs and symptoms of influenza by 32 hours. Disease severity in patients with confirmed influenza taking Tamiflu was also reduced by 38% compared to placebo. Moreover, Tamiflu reduced the incidence of complications associated with influenza treated with antibiotic therapy in otherwise healthy young adults by approximately 50%. These complications include bronchitis, pneumonia, sinusitis and otitis media. In these phase III clinical trials there was clear evidence of efficacy in the secondary endpoints related to antiviral activity in terms of both reduction of duration of virus shedding and reduction in the AUC of viral titres. Data from a treatment study in the elderly population have shown that Tamiflu 75 mg twice daily for five days was associated with a reduction in median duration of illness that was clinically relevant, and similar to that seen in the younger adult treatment studies. In a separate study, patients aged > 13 years with influenza and co-existing chronic cardiac and/or respiratory disease received the same regimen of either Tamiflu or placebo. No difference in the median time to alleviation of all symptoms was seen between patients taking Tamiflu or placebo, however the duration of febrile illness was reduced by approximately one day by receipt of Tamiflu. The proportion of patients shedding virus on days 2 and 4 was also markedly reduced by active treatment. There was no difference in the safety profile of Tamiflu in the at-risk populations compared to the general adult population.
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Treatment of influenza in children
One double-blind placebo controlled treatment trial was conducted in otherwise healthy children (65% influenza positive) aged 1 to 12 years (mean age 5.3), who had fever ( 100 F) plus one respiratory symptom (cough or coryza) when influenza virus was known to be circulating in the community. In this study 67% of influenza-infected patients were infected with influenza A and 33% with influenza B. Tamiflu treatment, started within 48 hours of onset of symptoms, significantly reduced the duration of illness by 35.8 hours compared to placebo. Duration of illness was defined as time to alleviation of cough, nasal congestion, resolution of fever, and return to normal health and activity. The proportion of patients developing acute otitis media was reduced by 40% in children receiving Tamiflu (29/183) vs placebo (53/200). Children receiving Tamiflu returned to normal health and activity almost 2 days earlier than those receiving placebo. A second study was completed in 334 asthmatic children aged 6 to 12 years old of which 53.6% were influenza-positive. In the oseltamivir-treated group the median duration of illness was not reduced significantly. By day 6 (the last day of treatment) FEV1 had increased by 10.8% in the oseltamivir- treated group compared to 4.7% on placebo (p = 0.0148) in this population.
Trials for prophylaxis of influenza
Prophylaxis of influenza in adults and adolescents
The efficacy of Tamiflu in preventing naturally occurring influenza illness has been demonstrated in three seasonal prophylaxis studies and two post exposure prophylaxis study in households. The primary efficacy parameter for all these studies was the incidence of laboratory confirmed clinical influenza. Laboratory confirmed clinical influenza was defined as oral temperature 99.0 oF/37.2 oC plus at least one respiratory symptom (cough, sore throat, nasal congestion) and at least one constitutional symptom (aches and pain, fatigue, headache, chills/sweats), all recorded within 24 hours, plus either a positive virus isolation or a fourfold increase in virus antibody titers from baseline. In a pooled analysis of two seasonal prophylaxis studies in healthy unvaccinated adults (aged 18 to 65 years), Tamiflu 75 mg once daily taken for 42 days during a community outbreak reduced the incidence of laboratory confirmed clinical influenza from 4.8% (25/519) for the placebo group to 1.2% (6/520) for the Tamiflu group. In a seasonal prophylaxis study in elderly residents of nursing homes, Tamiflu 75 mg once daily taken for 42 days reduced the incidence of laboratory confirmed clinical influenza from 4.4% (12/272) for the placebo group to 0.4% (1/276) for the Tamiflu group. About 80% of this elderly population were vaccinated, 14% of subjects had chronic airway obstructive disorders, and 43% had cardiac disorders. In a post-exposure prophylaxis study, household contacts (aged 13 years) who had no laboratory evidence of influenza at baseline, and who were living with an index case subsequently shown to have had influenza infection, were randomized to treatment (the ITTIINAB population). In this population Tamiflu 75 mg administered once daily within 2 days of onset of symptoms in the index case and continued for 7 days, reduced the incidence of laboratory confirmed clinical influenza in the contacts from 12% (24/200) in the placebo group to 1% (2/205) for the Tamiflu group (risk reduction 91.9%, p < 0.001). For the study population as a whole (the ITT population), including contacts of index cases in whom influenza infection was not confirmed, the incidence of laboratory confirmed clinical influenza was reduced from 7.4% (34/462) in the placebo group to 0.8% (4/493) for the Tamiflu group (risk reduction 89%, p < 0.001). Index cases did not receive Tamiflu in the study. In the ITT population 13.9%of contacts in the placebo group and 11.4% of contacts in the Tamiflu group had been vaccinated.
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The efficacy of Tamiflu in preventing naturally occurring influenza illness in adults and children has also been demonstrated in a post exposure prophylaxis study conducted in households in which index cases with rapid onset of fever, cough and/or coryza received twice daily treatment with Tamiflu for 5 days. The primary efficacy parameter for this study was the percentage of households with at least one secondary case of febrile laboratory confirmed influenza illness. A laboratory confirmed case was defined as a febrile illness (oral/otic temperature >= 100.0 oF/37.8 oC) plus cough and/or coryza, confirmed to be influenza by either detection of viral shedding within 2 days before or after the time that the fever was reported, and/or a four fold increase in influenza virus antibody titers from baseline to the day 30 sample. Household contacts were randomized (by household) to receive either once daily prophylaxis with oseltamivir for 10 days (Group P) or to receive treatment for 5 days upon the emergence of influenza-like illness (Group T). In households with an infected index case and where there was no laboratory evidence of influenza among the contacts at baseline (ITTIINAB), there was a 78.8% (p = 0.0008) reduction in households with infected contacts in Group T 22% (20/89) versus Group P 5% (4/84). In the population as a whole (ITT), including contacts of index cases in whom influenza infection was not confirmed, the prophylactic efficacy protection was 62.7% (p = 0.0042), Group T 20% (27/137) versus Group P 7% (10/137). A significant number of children aged 1 - 12 participated in this study, both as index cases and as contacts. In the ITTIINAB population of paediatric contacts, there was an 80.1% (p = 0.0206) reduction in the incidence of laboratory confirmed influenza in Group T 21% (15/70) versus Group P 4% (2/47). A similar reduction in clinical influenza was seen in the subset of paediatric contacts that also had paediatric index cases.
Prophylaxis of influenza in children
The efficacy of Tamiflu in preventing naturally occurring influenza illness has been demonstrated in a postexposure prophylaxis study in households that included children aged 1 to 12 years, both as index cases and as family contacts. The primary efficacy parameter for this study was the incidence of laboratory-confirmed clinical influenza. In this study, Tamiflu oral suspension 30 mg to 75 mg once daily taken for 10 days among children who were not already shedding virus at baseline reduced the incidence of laboratory-confirmed clinical influenza from 21% (15/70) in the group not receiving prophylaxis to 4% (2/47) in the group receiving prophylaxis.
Prophylaxis of influenza in immunocompromised patients
A double-blind, placebo controlled study was conducted for seasonal prophylaxis of influenza in 475 immunocompromised subjects, including 18 children 1 - 12 years old. Laboratory-confirmed clinical influenza, as defined by RT-PCR plus oral temperature 37.2 degC/99.0 degF plus cough and/or coryza, all recorded within 24 hours, was evaluated. Among subjects who were not already shedding virus at baseline, Tamiflu reduced the incidence of laboratory-confirmed clinical influenza from 3.0% (7/231) in the group not receiving prophylaxis to 0.4% (1/232) in the group receiving prophylaxis (see Table 3).
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Table 2: Incidence of influenza infection in immunocompromised patients
| Population | Placebo n / N (%) | Tamiflu 75 mg once daily n / N (%) | Treatment effect a | 95% CI for difference in proportions between treatments b | p -value c |
| Overall ITT | 7/238 (2.9%) | 5/237 (2.1%) | 28.3% | -2.3% to 4.1% | 0.772 |
| ITTII | 7/238 (2.9%) | 2/237 (0.8%) | 71.3% | -0.6% to 5.2% | - |
| ITTIINAB | 7/231 (3.0%) | 1/232 (0.4%) | 85.8% | 0.1% to 5.7% | - |
a
Treatment effect = (1 - Relative Risk) *100%
b
Calculated using Newcombe's method of combining Wilson score intervals without continuity correction
c
Comparison of Placebo versus Tamiflu using Fisher's exact test ITTII = intent-to-treat index-infected
ITTIINAB = intent-to-treat index-infected, not infected at baseline.
Viral resistance
Reduced sensitivity of viral neuraminidase
Clinical studies:
The risk of emergence of influenza viruses with reduced susceptibility or resistance to oseltamivir has been examined in clinical studies (see Table 3). All patients who were found to carry oseltamivir-resistant virus did so transiently, cleared the virus normally and showed no worsening of the underlying symptoms.
Table 3: Emergence of Influenza Viruses with Reduced Susceptibility or Resistance to Oseltamivir in Clinical Studies | ||
|---|---|---|
| Patient Population | Patients with Resistance Mutations (%) | |
| Phenotyping * | Genotyping and Phenotyping * | |
| Adults and Adolescents | 4/1245 (0.32%) | 5/1245 (0.4%) |
| Children (1 - 12 years) | 19/464 (4.1%) | 25/464 (5.4%) |
* Full genotyping was not performed in all studies. In clinical studies conducted in post-exposure (7 days), post-exposure within household groups (10 days) and seasonal (42 days) prophylaxis of influenza in immunocompetent persons, there was no evidence for emergence of drug resistance associated with the use of Tamiflu. There was no resistance observed during a 12-week seasonal prophylaxis study in immunocompromised subjects.
Clinical and surveillance data: Natural mutations associated with reduced susceptibility to oseltamivir in vitro have been detected in influenza A and B viruses isolated from patients without exposure to oseltamivir. For example, in 2008 the oseltamivir resistance-associated substitution H275Y was found in > 99 % of circulating 2008 H1N1 influenza isolates in Europe, while the 2009 H1N1 influenza ("swine flu") was almost uniformly susceptible to oseltamivir. Resistant strains have also been isolated from both immunocompetent and immunocompromised patients treated with oseltamivir. The susceptibility
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to oseltamivir and the prevalence of such viruses appears to vary seasonally and geographically. Oseltamivir resistance has also been reported in patients with pandemic H1N1 influenza in connection with both therapeutic and prophylactic regimens. The rate of emergence of resistance may be higher in the youngest age groups, and in immunocompromised patients. Oseltamivir-resistant viruses isolated from oseltamivir-treated patients and oseltamivir-resistant laboratory strains of influenza viruses have been found to contain mutations in N1 and N2 neuraminidases. Resistance mutations tend to be viral sub-type specific. Prescribers should consider available information on influenza virus drug susceptibility patterns for each season when deciding whether to use Tamiflu (for the latest information, please refer to WHO and/or local government websites).
Pharmacokinetic Properties
Oseltamivir is readily absorbed from the gastrointestinal tract after oral administration of oseltamivir phosphate and is extensively converted predominantly by hepatic esterases to the active metabolite. Plasma concentrations of the active metabolite are measurable within 30 minutes, reach near maximal levels in 2 to 3 hours post dose, and substantially exceed (> 20-fold) those of the pro-drug. At least 75% of an oral dose reaches the systemic circulation as the active metabolite. Plasma concentrations of active metabolite are proportional to dose and are unaffected by co-administration with food (see Dosage and Administration).
The mean volume of distribution (VSS) of the active metabolite is approximately 23 litres in humans. The active moiety reaches all key sites of influenza infection as shown by studies in the ferret, rat and rabbit. In these studies, anti-viral concentrations of the active metabolite were seen in the lung, bronchoalveolar lavage, nasal mucosa, middle ear and trachea following oral administration of doses of oseltamivir phosphate. The binding of the active metabolite to human plasma protein is negligible (approximately 3%). The binding of the pro-drug to human plasma protein is 42%. These levels are insufficient to cause significant interactions.
Oseltamivir phosphate is extensively converted to the active metabolite by esterases located predominantly in the liver. Neither oseltamivir nor the active metabolite are substrates for, or inhibitors of, cytochrome P450 isoforms (see Interactions with other Medicines).
Absorbed oseltamivir is primarily (> 90%) eliminated by conversion to the active metabolite. The active metabolite is not further metabolised and is eliminated in the urine. Peak plasma concentrations of the active metabolite decline with a half-life of 6 to 10 hours in most subjects.
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The active substance is eliminated entirely (> 99%) by renal excretion. Renal clearance (18.8 L/h) exceeds glomerular filtration rate (7.5 L/h) indicating that tubular secretion in addition to glomerular filtration occurs. Less than 20% of an oral radiolabelled dose is eliminated in faeces.
Patients with renal impairment
Administration of 100 mg of Tamiflu twice daily for five days to patients with various degrees of renal impairment showed that exposure to the active metabolite is inversely proportional to declining renal function. A population pharmacokinetic model describing the impact of creatinine clearance (CrCL) on oseltamivir and oseltamivir carboxylate pharmacokinetics was developed and qualified for simulation using 80 subjects with varying degrees of renal function. Subjects had dense pharmacokinetic profiles and were identified from three clinical studies; a study in subjects with either normal renal function or mild, moderate or severe renal impairment (WP15648) and two studies in healthy subjects receiving a range of single (WP15517) or multiple doses of oseltamivir (WP15525). Simulations were performed and suitable regimens using available capsule formulations were selected on the basis to provide oseltamivir carboxylate exposures considered safe and efficacious in clinical trials. Refer to Dosage and Administration for recommended dosing for patients with severe, moderate and mild renal impairment. Two clinical studies were performed to evaluate the pharmacokinetic, safety and tolerability of oseltamivir and oseltamivir carboxylate in end stage renal disease patients undergoing haemodialysis (HD) and continuous ambulatory peritoneal dialysis (CAPD). In study PP15974 patients undergoing either CAPD or HD received a single 75 mg capsule of oseltamivir, whereas in study NP16472 patients received 30 mg oseltamivir oral suspension for 6.5 weeks, with CAPD patients receiving a single dose per week and HD patients a dose after alternate dialysis sessions. In order to assist in determining appropriate dosing recommendations in HD, a population pharmacokinetic model for HD was constructed and qualified for simulation. Suitable regimens using available capsule formulations were selected on their basis to achieve oseltamivir carboxylate plasma trough levels in subjects with normal renal function dosed at 75 mg twice daily for treatment, or 75 mg oseltamivir given orally once daily for prophylaxis. Refer to Dosage and Administration for recommended dosing for patients with end stage renal disease undergoing haemodialysis and continuous ambulatory peritoneal dialysis.
Patients with hepatic impairment
In-vitro studies have shown that exposure to oseltamivir is not expected to be increased significantly nor is exposure to the active metabolite significantly decreased in patients with hepatic impairment (see Special dosage instructions).
Elderly
Exposure to the active metabolite at steady state was 25 to 35% higher in elderly (age range 65 to 78) compared to young adults who were given comparable doses of Tamiflu. Half-lives observed in the elderly were similar to those seen in young adults. On the basis of exposure and tolerability, dosage adjustments are not required for elderly patients for either the treatment or prophylaxis of influenza (see Special dosage instructions).
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Children >= 1 year of age The pharmacokinetics of Tamiflu have been evaluated in a single dose pharmacokinetic studies in children aged 1 to 16 years. Multiple dose pharmacokinetics were studied in a small number of children aged 3 to 12 enrolled in a clinical trial. The rate of clearance of the active metabolite, corrected for bodyweight, was faster in younger children, than in adults, resulting in lower exposure in these children for a given mg/kg dose. Doses of 2 mg/kg and unit doses of 30 and 45 mg, administered to children in the appropriate categories according to the recommendation in the Dosage and Method of Administration section yield oseltamivir carboxylate exposures comparable to those achieved in adults receiving a single 75 mg capsule dose (approximately 1 mg/kg). The pharmacokinetics of oseltamivir in children over 12 years of age are similar to those in adults.
Preclinical data reveal no special hazard for humans based on conventional studies of safety pharmacology, repeated dose toxicity and genotoxicity. Three studies for carcinogenic potential (2 year rat and mouse studies with oseltamivir, and a 6 month transgenic Tg:AC mouse assay performed with the active metabolite) were negative. Teratology studies have been conducted in rats and rabbits at doses up to 1500 mg/kg/day and 500 mg/kg/day, respectively. No effects on embryo-foetal development were observed. A rat fertility study up to a dose of 1500 mg/kg/day demonstrated no adverse effects on either sex. In pre-/post- natal rat studies, prolonged parturition was noted at 1500 mg/kg/day: the safety margin between human exposure and the highest no effect dose (500 mg/kg/day) in rats is 480-fold for oseltamivir and 44-fold for the active metabolite, respectively. Foetal exposure in the rats and rabbits was approximately 15 to 20% of that of the mother. In lactating rats, oseltamivir and the active metabolite are excreted in milk. Limited data indicate that oseltamivir and the active metabolite are excreted in human milk. Extrapolation of the animal data provides estimates of 0.01 mg/day and 0.3 mg/day for the respective compounds. A potential for skin sensitisation to oseltamivir was observed in a "maximisation" test in guinea pigs. Approximately 50% of the animals treated with the unformulated active ingredient showed erythema after challenging the induced animals. Reversible irritancy of the rabbits' eyes was detected. Very high oral single doses of oseltamivir phosphate had no effect in adult rats, however, such doses resulted in toxicity in juvenile seven-day-old rat pups, including death. These effects were seen at doses of 657 mg/kg/day and higher. No adverse effects were seen following a single dose of 500 mg/kg, nor with chronic dosing of 500 mg/kg/day from day 7 to day 21 post partum.
Reports of overdose with Tamiflu have been received from clinical trials and during post-marketing experience. In the majority of cases reporting overdose, no adverse events were reported. Adverse events reported following overdose were similar in nature and distribution to those observed with therapeutic doses of Tamiflu described in Adverse Effects Contact the Poisons Information Centre for advice on management of overdosage.
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Capsules:
Tamiflu capsules 30 mg, 45 mg and 75 mg are available in blister packages of 10 capsules. Store Tamiflu capsules below 25degC.
Note: Tamiflu 30 mg and 45 mg capsules are currently not available.
Powder for oral suspension:
Tamiflu powder for oral suspension 6 mg/mL is available in 100 mL bottle pack with 13 g of white to yellow white powder, a bottle adaptor, a plastic oral dispenser and a measuring plastic cup. After constitution with 55 mL of water, the usable volume of oral suspension allows the retrieval of 10 doses of 30 mg oseltamivir. After constitution, the suspension can be stored at room temperature (below 25 degC) for up to 10 days or in a refrigerator (2 - 8 degC) for up to 17 days. Tamiflu oral suspension should not be frozen. These medicines should not be used after the expiry date shown on the pack.
Home-prepared mixture (by opening 75 mg capsules):
Home-prepared Tamiflu mixture must be swallowed immediately after preparation.
Pharmacy-compounded suspension:
After pharmacy compounding of Tamiflu capsules the 15 mg/mL suspension can be stored at room temperature (below 25 oC) for up to 3 weeks (21 days) or in a refrigerator (2 - 8 oC) for up 6 weeks. Pharmacy-compounded Tamiflu suspension should not be frozen.
Special Remarks
Preparation of Tamiflu 6 mg/mL powder for oral suspension
It is recommended that Tamiflu powder for oral suspension be constituted by the pharmacist prior to dispensing to the patient (see Dosage and Administration):
Tap the closed bottle several times to loosen the powder.
Measure 55 mL of water. Use the measuring cup (where provided) and fill it to the indicated level.
Add all 55 mL of water for constitution to the bottle and shake the closed bottle well for 15 seconds. The final constituted volume is 65 mL.
Remove the child-resistant cap and push bottle adapter into neck of bottle.
Close bottle with child-resistant cap tightly. This will assure the proper seating of the bottle adapter in the bottle and child-resistant status of the cap.
Disposal of Medicines
The release of medicines into the environment should be minimised. Medicines should not be disposed of via wastewater and disposal through household waste should be avoided. Unused or expired medicine should be returned to a pharmacy for disposal.
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Tamiflu 30mg and 45mg capsules; and Tamiflu 6mg/mL powder for oral suspension: Prescription Only Medicine. Tamiflu 75mg capsules: Pharmacist Only Medicine for the treatment or prophylaxis of influenza in adults and children aged 13 years and older who have been exposed to the influenza virus. For children 12 years of age and under, Tamiflu 75mg capsules is a Prescription Only Medicine for the treatment or prevention of influenza.
Roche Products (New Zealand) Limited PO Box 109113 Newmarket Auckland 1149 NEW ZEALAND Customer enquiries: 0800 656 464
1 October 2013
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