Tamiflu Drug Information
Generic name: OSELTAMIVIR PHOSPHATE
Uses of Tamiflu
Treatment of Influenza
TAMIFLU is indicated for the treatment of acute, uncomplicated illness due to influenza A and B infection in patients 2 weeks of age and older who have been symptomatic for no more than 48 hours.
Prophylaxis of Influenza
TAMIFLU is indicated for the prophylaxis of influenza A and B in patients 1 year and older.
Limitations of Use
TAMIFLU is not a substitute for early influenza vaccination on an annual basis as recommended by the Centers for Disease Control and Prevention Advisory Committee on Immunization Practices. Influenza viruses change over time. Emergence of resistance substitutions could decrease drug effectiveness.
Other factors (for example, changes in viral virulence) might also diminish clinical benefit of antiviral drugs. Prescribers should consider available information on influenza drug susceptibility patterns and treatment effects when deciding whether to use TAMIFLU . TAMIFLU is not recommended for patients with end-stage renal disease not undergoing dialysis.
Dosage & Administration of Tamiflu
| Any weight | 3 mg/kg |
|---|---|
| 15 kg or less | 30 mg |
| 15.1 kg to 23 kg | 45 mg |
| 23.1 kg to 40 kg | 60 mg |
| 40.1 kg or more | 75 mg |
Side Effects of Tamiflu
Clinical Trials Experience
Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. Adverse Reactions from Treatment and Prophylaxis Trials in Adult and Adolescent Subjects (13 years of age and older) The overall safety profile of TAMIFLU is based on data from 2,646 adult and adolescent subjects that received the recommended dosage of 75 mg orally twice daily for 5 days for treatment of influenza and 1,943 adult and adolescent subjects that received the recommended dosage of 75 mg orally once daily for up to 6 weeks for prophylaxis of influenza in clinical trials. The most common adverse reactions in the pooled treatment and pooled prophylaxis trials in adults and adolescents are displayed in Table 5. The majority of these adverse reactions were reported on a single occasion, occurred on either the first or second treatment day and resolved spontaneously within 1-2 days.
This summary includes otherwise healthy adults/adolescents and subjects "at risk" (subjects 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 subjects "at risk" was qualitatively similar to that in otherwise healthy adults/adolescents. Table 5 Adverse Reactions Occurring in ≥1% of Adults and Adolescents (13 years of age and older) in Treatment and Prophylaxis Trials Adverse reactions that occurred in ≥1% of TAMIFLU-treated adults and adolescents and ≥1% greater in TAMIFLU-treated subjects compared to placebo-treated subjects in either the treatment or prophylaxis trials. System Organ Class Treatment Trials Prophylaxis Trials Adverse Reaction TAMIFLU 75 mg twice daily (n = 2646) Placebo (n = 1977) TAMIFLU 75 mg once daily (n = 1943) Placebo (n = 1586) Gastrointestinal Disorders Nausea 10% 6% 8% 4% Vomiting 8% 3% 2% 1% Nervous System Disorders Headache 2% 1% 17% 16% General Disorders Pain <1% <1% 4% 3% Adverse Reactions from Treatment and Prophylaxis Trials in Pediatric Subjects (1 year to 12 years of age) A total of 1,481 pediatric subjects (including otherwise healthy pediatric subjects aged 1 year to 12 years and asthmatic pediatric subjects aged 6 to 12 years) participated in clinical trials of TAMIFLU for the treatment of influenza.
A total of 859 pediatric subjects received treatment with TAMIFLU for oral suspension either at a 2 mg per kg twice daily for 5 days or weight-band dosing. Vomiting was the only adverse reaction reported at a frequency of > 1% in subjects receiving TAMIFLU (16%) compared to placebo (8%). Amongst the 148 pediatric subjects aged 1 year to 12 years who received TAMIFLU at doses of 30 to 60 mg once daily for 10 days in a post-exposure prophylaxis study in household contacts (n = 99), and in a separate 6–week seasonal influenza prophylaxis safety study (n = 49), vomiting was the most frequent adverse reaction (8% on TAMIFLU versus 2% in the no prophylaxis group). Adverse Reactions from Treatment Trials in Pediatric Subjects (2 weeks to less than 1 year of age) Assessment of adverse reactions in pediatric subjects 2 weeks to less than 1 year of age was based on two open-label studies that included safety data on 135 influenza-infected subjects 2 weeks to less than 1 year of age (including premature infants at least 36 weeks post conceptional age) exposed to TAMIFLU at doses ranging from 2 to 3.5 mg per kg of the formulation for oral suspension twice daily orally for 5 days. The safety profile of TAMIFLU was similar across the age range studied, with vomiting (9%), diarrhea (7%) and diaper rash (7%) being the most frequently reported adverse reactions, and was generally comparable to that observed in older pediatric and adult subjects.
Adverse Reactions from the Prophylaxis Trial in Immunocompromised Subjects In a 12-week seasonal prophylaxis study in 475 immunocompromised subjects, including 18 pediatric subjects 1 year to 12 years of age, the safety profile in the 238 subjects receiving TAMIFLU 75 mg once daily was consistent with that previously observed in other TAMIFLU prophylaxis clinical trials .
Postmarketing Experience
The following adverse reactions have been identified during post-approval use of TAMIFLU. Because these reactions are reported voluntarily from a population of uncertain size, it is not possible to reliably estimate their frequency or establish a causal relationship to TAMIFLU exposure. General disorders and administration site conditions: Swelling of the face or tongue, allergy, anaphylactic/anaphylactoid reactions, hypothermia Skin and subcutaneous tissue disorders: Rash, dermatitis, urticaria, eczema, toxic epidermal necrolysis, Stevens-Johnson Syndrome, erythema multiforme Gastrointestinal Disorders: Gastrointestinal bleeding, hemorrhagic colitis Cardiac Disorders: Arrhythmia Hepatobiliary Disorders: Hepatitis, abnormal liver function tests Nervous System Disorders: Seizure Metabolism and Nutrition Disorders: Aggravation of diabetes Psychiatric Disorders: Abnormal behavior, delirium, including symptoms such as hallucinations, agitation, anxiety, altered level of consciousness, confusion, nightmares, delusions
Warnings & Cautions for Tamiflu
Serious Skin/Hypersensitivity Reactions Cases of anaphylaxis and serious skin reactions including toxic
epidermal necrolysis, Stevens-Johnson Syndrome, and erythema multiforme have been reported in postmarketing experience with TAMIFLU. Stop TAMIFLU and institute appropriate treatment if an allergic-like reaction occurs or is suspected. The use of TAMIFLU is contraindicated in patients with known serious hypersensitivity to TAMIFLU .
Neuropsychiatric Events
There have been postmarketing reports of delirium and abnormal behavior leading to injury, and in some cases resulting in fatal outcomes, in patients with influenza who were receiving TAMIFLU . Because these events were reported voluntarily during clinical practice, estimates of frequency cannot be made but they appear to be uncommon based on TAMIFLU usage data. These events were reported primarily among pediatric patients and often had an abrupt onset and rapid resolution. The contribution of TAMIFLU to these events has not been established.
Influenza can be associated with a variety of neurologic and behavioral symptoms that can include events such as hallucinations, delirium, and abnormal behavior, 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. Closely monitor TAMIFLU-treated patients with influenza for signs of abnormal behavior.
If neuropsychiatric symptoms occur, evaluate the risks and benefits of continuing TAMIFLU for each patient.
Risk of Bacterial Infections
There is no evidence for efficacy of TAMIFLU in any illness caused by pathogens other than influenza viruses. Serious bacterial infections may begin with influenza-like symptoms or may coexist with or occur as complications during the course of influenza. TAMIFLU has not been shown to prevent such complications.
Prescribers should be alert to the potential for secondary bacterial infections and treat them as appropriate.
Fructose Intolerance in Patients with Hereditary Fructose Intolerance Fructose can be harmful
to patients with hereditary fructose intolerance. One dose of 75 mg TAMIFLU for oral suspension delivers 2 grams of sorbitol. This is above the daily maximum limit of sorbitol for patients with hereditary fructose intolerance and may cause dyspepsia and diarrhea.
Drug Interactions with Tamiflu
Influenza Vaccines Live Attenuated Influenza Vaccine
The concurrent use of TAMIFLU with live attenuated influenza vaccine (LAIV) intranasal has not been evaluated. However, because of the potential for TAMIFLU to inhibit replication of live vaccine virus and possibly reduce the efficacy of LAIV, avoid administration of LAIV within 2 weeks before or 48 hours after TAMIFLU administration, unless medically indicated. Inactivated Influenza Vaccine Inactivated influenza vaccine can be administered at any time relative to use of TAMIFLU.
Drugs Without Clinically Significant Drug Interaction with
TAMIFLU No dose adjustments are needed for either oseltamivir or the concomitant drug when coadministering oseltamivir with amoxicillin, acetaminophen, aspirin, cimetidine, antacids (magnesium and aluminum hydroxides and calcium carbonates), rimantadine, amantadine, or warfarin .
Pregnancy Safety for Tamiflu
Pregnancy Risk Summary There are no adequate and well-controlled studies with TAMIFLU in pregnant women to inform a drug-associated risk of adverse developmental outcomes. Available published epidemiological data suggest that TAMIFLU, taken in any trimester, is not associated with an increased risk of birth defects. However, these studies individually are limited by small sample sizes, use of different comparison groups, and some lacked information on dose, which preclude a definitive assessment of the risk . In animal reproduction studies with oseltamivir, no adverse developmental effects were observed at clinically relevant exposures (see Data ). The background risk of major birth defects and miscarriage for the indicated populations is unknown.
All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage is 2-4% and 15-20%, respectively. Clinical Considerations Disease-Associated Maternal and/or Embryo/Fetal Risk Pregnant women are at higher risk of severe complications from influenza, which may lead to adverse pregnancy and/or fetal outcomes including maternal death, still births, birth defects, preterm delivery, low birth weight and small for gestational age.
Data Human Data Published prospective and retrospective observational studies of more than 5,000 women exposed to TAMIFLU during pregnancy, including more than 1,000 women exposed in the first trimester, suggest that the observed rate of congenital malformations was not increased above the rate in the general comparison population, regardless of when therapy was administered during the gestational period. However, individually, none of these studies had adequate sample sizes and some lacked information on dose, which preclude a definitive assessment of the risk. Animal Data Oseltamivir was administered orally during organogenesis to pregnant rats (at 50, 250, or 1500 mg/kg/day on gestation days 6 to 17) and rabbits (at 50, 150, or 500 mg/kg/day on gestation days 6 to 18). In rats, embryo-fetal effects consisting of an increased incidence of minor skeletal malformations were observed at a maternally toxic dose (1500 mg/kg/day), resulting in systemic drug exposures (based on AUC for oseltamivir carboxylate) 190 times human exposures at the maximum recommended human dose (MRHD) of TAMIFLU (75 mg twice a day). In the rabbit study, embryo-fetal effects consisting of an increased incidence of minor skeletal abnormalities and variants were observed at maternally toxic doses (≥150 mg/kg/day) resulting in systemic exposures (based on AUC for oseltamivir carboxylate) ≥8 times human exposures at the MRHD of TAMIFLU. In prenatal and postnatal development studies in rats, oseltamivir was administered orally (at 50, 250, 500, or 1500 mg/kg/day) from organogenesis through late gestation, delivery, and lactation (gestation day 6 to postpartum/lactation day 20). Prolonged parturition duration and reduced offspring viability were observed at a maternally toxic dose (1500 mg/kg/day). No adverse maternal or offspring effects were observed at doses ≤500 mg/kg/day, resulting in systemic drug exposures (based on AUC for oseltamivir carboxylate) 44 times human exposures at the MRHD of TAMIFLU.
Pediatric Use of Tamiflu
Pediatric Use Treatment of Influenza The safety and efficacy of TAMIFLU for the treatment of influenza in pediatric patients 2 weeks old to 17 years of age has been established and is based on: 13 to 17 years of age: Safety and efficacy in adolescent patients 13 to 17 years of age was supported by adequate and well-controlled trials in adults and adolescents and younger pediatric patients and safety data in adolescents treated with TAMIFLU in a study of treatment and prophylaxis. 1 year to 12 years of age: Safety and efficacy in pediatric patients 1 year to 12 years of age was supported by results of one double-blind, placebo-controlled trial in 452 pediatric patients with influenza in whom TAMIFLU 2 mg per kg twice daily or placebo was administered within 48 hours of symptom onset. Additional safety information was provided in a double-blind, placebo-controlled trial in pediatric patients 6 to 12 years of age with known asthma. Efficacy could not be established in pediatric patients with asthma. 2 weeks to less than 1 year of age: Safety and efficacy in pediatric patients 2 weeks to less than 1 year of age is supported by adequate and well-controlled trials in adults and older pediatric patients and two open-label trials of TAMIFLU (2 to 3.5 mg per kg twice daily for 5 days) in 136 pediatric subjects 2 weeks to less than 1 year of age.
In these two trials, the oseltamivir plasma concentrations in these subjects were similar to or higher than the oseltamivir plasma concentrations observed in older pediatric subjects and adults . The safety and efficacy of TAMIFLU for treatment of influenza in pediatric patients less than 2 weeks of age have not been established. Prophylaxis of Influenza The safety and efficacy of TAMIFLU for the prophylaxis of influenza in pediatric patients 1 year to 17 years old has been established and is based on: 13 to 17 years of age: Prophylaxis in adolescent patients 13 to 17 years of age is supported by one randomized, placebo-controlled post-exposure household prophylaxis trial of TAMIFLU 75 mg taken orally once daily for 7 days in household contacts including 207 adolescents. 1 year to 12 years of age: TAMIFLU for prophylaxis in pediatric patients 1 year to 12 years of age is supported by one randomized, open-label, post-exposure household prophylaxis trial including pediatric subjects 1 year to 12 years of age who received 30 to 60 mg of TAMIFLU for oral suspension (supplied as powder) taken orally once daily for 10 days. Additional safety information was provided in a 6-week seasonal prophylaxis (community outbreak) safety study in 49 patients 1 year to 12 years of age.
The safety and efficacy of TAMIFLU for prophylaxis of influenza have not been established for pediatric patients less than 1 year of age.
Contraindications for Tamiflu
is contraindicated in patients with known serious hypersensitivity to oseltamivir or any component of the product. Severe allergic reactions have included anaphylaxis and serious skin reactions including toxic epidermal necrolysis, Stevens-Johnson Syndrome, and erythema multiforme . Patients with known serious hypersensitivity to oseltamivir or any of the components of TAMIFLU
Overdosage Information for Tamiflu
Reports of overdoses with TAMIFLU have been received from clinical trials and during postmarketing experience. In the majority of cases reporting overdose, no adverse reactions were reported. Adverse reactions reported following overdose were similar in nature to those observed with therapeutic doses of TAMIFLU .
Clinical Studies of Tamiflu
Treatment of Influenza Adults Two randomized, placebo-controlled, double-blind clinical trials of
TAMIFLU were conducted in adults between 18 and 65 years old, one in the U.S. and one outside the U.S., for the treatment of acute uncomplicated influenza. Eligible subjects had fever of at least 100ºF, accompanied by at least one respiratory symptom (cough, nasal symptoms, or sore throat) and at least one systemic symptom (myalgia, chills/sweats, malaise, fatigue, or headache), and influenza virus was known to be circulating in the community. Subjects were randomized to receive oral TAMIFLU or placebo for 5 days.
All enrolled subjects were allowed to take fever-reducing medications. Of 1,355 subjects enrolled in these two trials, 849 (63%) subjects were influenza-infected (median age 34 years; 52% male; 90% Caucasian; 31% smokers). Of the 849 influenza-infected subjects, 95% were infected with influenza A, 3% with influenza B, and 2% with influenza of unknown type. Study medication was started within 40 hours of onset of symptoms and administered twice daily for 5 days.
Subjects were required to self-assess the influenza-associated symptoms (nasal congestion, sore throat, cough, aches, fatigue, headaches, and chills/sweats) twice daily as "none," "mild," "moderate," or "severe". Time to improvement was calculated from the time of treatment initiation to the time when all symptoms were assessed as "none" or "mild". In both trials, there was a 1.3-day reduction in the median time to improvement in influenza-infected subjects who received TAMIFLU 75 mg twice a day for 5 days compared to subjects who received placebo. Subgroup analyses by gender showed no differences in the treatment effect of TAMIFLU in men and women. In the treatment of influenza, no increased efficacy was demonstrated in subjects who received higher doses of TAMIFLU. Adolescents and Adults with Chronic Cardiac or Respiratory Disease A double-blind, placebo-controlled, multicenter trial was unable to demonstrate efficacy of TAMIFLU (75 mg twice daily for 5 days) in the treatment of influenza in adult and adolescent subjects (13 years or older) with chronic cardiac (excluding chronic idiopathic hypertension) or respiratory diseases, as measured by time to alleviation of all symptoms.
However, in patients treated with TAMIFLU there was a more rapid cessation of febrile illness. No difference in the incidence of influenza complications was observed between the treatment and placebo groups in this population. Geriatric Subjects Three double-blind placebo-controlled treatment trials were conducted in subjects who were at least 65 years of age in three consecutive seasons.
The enrollment criteria were similar to that of adult trials with the exception of fever being defined as higher than 97.5°F. Of 741 subjects enrolled, 476 (65%) subjects were influenza-infected; of these, 95% were infected with influenza type A and 5% with influenza type B. In the pooled analysis, there was a 1-day reduction in the median time to improvement in influenza-infected subjects who received TAMIFLU 75 mg twice daily for 5 days compared to those who received placebo (p=NS) . Some seasonal variability was noted in the clinical efficacy outcomes. Pediatric Subjects (1 year to 12 years of age) One double-blind placebo-controlled treatment trial was conducted in pediatric subjects aged 1 year to 12 years (median age 5 years) who had fever (at least 100ºF) plus one respiratory symptom (cough or coryza) when influenza virus was known to be circulating in the community. Of 698 subjects enrolled in this trial, 452 (65%) were influenza-infected (50% male; 68% Caucasian). Of the 452 influenza-infected subjects, 67% were infected with influenza A and 33% with influenza B. Efficacy in this trial was determined by the time to alleviation or resolution of influenza signs and symptoms, measured by a composite endpoint that required the following four individual conditions be met: i) alleviation of cough, ii) alleviation of coryza, iii) resolution of fever, and iv) parental opinion of a return to normal health and activity.
TAMIFLU treatment of 2 mg per kg twice daily, started within 48 hours of onset of symptoms, reduced the total composite time to freedom from illness by 1.5 days compared to placebo. Subgroup analyses by gender showed no differences in the treatment effect of TAMIFLU in male and female pediatric subjects. Pediatric Subjects (2 weeks to less than 1 year of age) Two open-label trials evaluated the safety and pharmacokinetics of oseltamivir and oseltamivir carboxylate in influenza-infected pediatric subjects 2 weeks to less than 1 year of age (including premature infants at least 36 weeks post conceptional age). Subjects received TAMIFLU at doses ranging from 2 to 3.5 mg per kg twice daily for 5 days depending on subject age.
These clinical trials were not designed to evaluate clinical efficacy or virologic response. Of the 136 subjects under the age of 1 year enrolled and dosed in the trials, the majority of the subjects were male (55%), white (79%), non-Hispanic (74%), full term (76%) and infected with influenza A (80%). Pharmacokinetic data indicated that a dose of 3 mg per kg twice daily in pediatric subjects 2 weeks to less than 1 year of age provided TAMIFLU concentrations similar to or higher than those observed in older pediatric subjects and adults receiving the approved dose and provided the basis for approval .
Prophylaxis of Influenza Adult and Adolescent Subjects (13 years of age and
older) The efficacy of TAMIFLU in preventing naturally occurring influenza illness has been demonstrated in three seasonal prophylaxis (community outbreak) clinical trials and one post-exposure prophylaxis trial in household contacts. The efficacy endpoint for all of these trials was the incidence of laboratory-confirmed clinical influenza defined as meeting all the following criteria (all signs and symptoms must have been recorded within 24 hours): oral temperature greater than or equal to 99.0ºF (37.2ºC), at least one respiratory symptom (cough, sore throat, nasal congestion), at least one constitutional symptom (aches and pain, fatigue, headache, chills/sweats), and either a positive virus isolation or a four-fold increase in virus antibody titers from baseline. In a pooled analysis of two seasonal prophylaxis trials 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 5% (25/519) for the placebo group to 1% (6/520) for the TAMIFLU group.
In the seasonal (community outbreak) prophylaxis trial in elderly residents of skilled nursing homes, about 80%, 43%, and 14% of the subjects were vaccinated, had cardiac disorders, and had chronic airway obstructive disorders, respectively. In this trial, subjects were randomized to TAMIFLU 75 mg once daily or placebo taken orally for 42 days. The incidence of laboratory-confirmed clinical influenza was 4% (12/272) in the placebo-treated subjects compared to less than 1% (1/276) in the TAMIFLU-treated subjects.
In the post-exposure prophylaxis trial in household contacts (aged 13 years or older) of an index influenza case, TAMIFLU 75 mg once daily or placebo taken orally was administered within 48 hours of onset of symptoms in the index case and continued for 7 days (index cases did not receive TAMIFLU treatment). The incidence of laboratory-confirmed clinical influenza was 12% (24/200) in the placebo-treated subjects compared to 1% (2/205) in the TAMIFLU-treated subjects. Pediatric Subjects (1 year to 12 years of age) The efficacy of TAMIFLU in preventing naturally occurring influenza illness was demonstrated in a randomized, open-label post-exposure prophylaxis trial in household contacts that included pediatric subjects aged 1 year to 12 years, both as index cases and as family contacts. All index cases in this trial received TAMIFLU for oral suspension 30 to 60 mg taken orally once daily for 10 days.
The efficacy parameter was the incidence of laboratory-confirmed clinical influenza in the household. Laboratory-confirmed clinical influenza was defined as meeting all of the following criteria: oral temperature at least 100°F (37.8°C), cough and/or coryza recorded within 48 hours, and either a positive virus isolation or a four-fold or greater increase in virus antibody titers from baseline or at illness visits. Among household contacts 1 year to 12 years of age not already shedding virus at baseline, the incidence of laboratory-confirmed clinical influenza was lower in the group who received TAMIFLU prophylaxis compared to the group who did not receive TAMIFLU prophylaxis.
Immunocompromised Subjects A double-blind, placebo-controlled trial was conducted for seasonal prophylaxis of influenza in 475 immunocompromised subjects (including 18 pediatric subjects 1 year to 12 years of age) who had received solid organ (n=388; liver, kidney, liver and kidney) or hematopoietic stem cell transplants (n=87). Median time since transplant for solid organ transplant recipients was 1,105 days for the placebo group and 1,379 days for the TAMIFLU group. Median time since transplant for hematopoietic stem cell transplant recipients was 424 days for the placebo group and 367 days for the TAMIFLU group. Approximately 40% of subjects received influenza vaccine prior to entering the study.
The primary efficacy endpoint was the incidence of confirmed clinical influenza, defined as oral temperature higher than 99.0°F (37.2°C) plus cough and/or coryza, all recorded within 24 hours, plus either a positive virus culture or a four-fold increase in virus antibody titers from baseline. Subjects received treatment with TAMIFLU 75 mg or placebo once daily by mouth for 12 weeks. The incidence of confirmed clinical influenza was 3% (7/238) in the placebo group compared with 2% (5/237) in the TAMIFLU group; this difference was not statistically significant.
A secondary analysis was performed using the same clinical symptoms and RT-PCR for laboratory confirmation of influenza infection. Among subjects who were not already shedding virus at baseline, the incidence of RT-PCR-confirmed clinical influenza infection was 3% (7/231) in the placebo group and <1% (1/232) in the TAMIFLU group.
Drug information sourced from the FDA. This content is for informational purposes only and does not constitute medical advice. Consult a healthcare professional before making any medication decisions.
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