The following adverse reactions have been identified during post-approval use of oseltamivir phosphate. 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 oseltamivir phosphate 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 [see Warnings and Precautions ( 5.1)]
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 [see Warnings and Precautions ( 5.2)]
Live Attenuated Influenza Vaccine
The concurrent use of oseltamivir phosphate capsules with live attenuated influenza vaccine (LAIV) intranasal has not been evaluated. However, because of the potential for oseltamivir phosphate capsules 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 oseltamivir phosphate capsules administration, unless medically indicated.
Inactivated Influenza Vaccine
Inactivated influenza vaccine can be administered at any time relative to use of oseltamivir phosphate capsules.
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 [see Clinical Pharmacology ( 12.3)] .
There are no adequate and well-controlled studies with oseltamivir phosphate in pregnant women to inform a drug associated risk of adverse developmental outcomes. Available published epidemiological data suggest that oseltamivir phosphate, 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 [
see Data and Clinical Pharmacology (12.3) ]. In animal reproduction studies with oseltamivir, no adverse developmental effects were observed at clinically relevant exposures (
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.
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.
Published prospective and retrospective observational studies of more than 5,000 women exposed to oseltamivir phosphate 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.
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 oseltamivir phosphate capsules (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 oseltamivir phosphate capsules.
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 oseltamivir phosphate capsules.
Based on limited published data, oseltamivir and oseltamivir carboxylate have been shown to be present in human milk at low levels considered unlikely to lead to toxicity in the breastfed infant. Postmarketing experience has not reported any information to suggest serious adverse effects of oseltamivir exposure via breast milk in infants. It is not known if oseltamivir affects human milk production. The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for oseltamivir phosphate capsules and any potential adverse effects on the breastfed child from the drug or from the underlying maternal condition.
Treatment of Influenza
The safety and efficacy of oseltamivir phosphate for the treatment of influenza in pediatric patients 2 weeks old to 17 years of age has been established [see Dosage and Administration ( 2.2), Clinical Pharmacology ( 12.3), and Clinical Studies ( 14.1)] 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 oseltamivir phosphate 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 oseltamivir phosphate 2 mg per kg twice daily or placebo was administered within 48 hours of symptom onset [see Clinical Studies ( 14.1)]. 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 oseltamivir phosphate (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 [see Clinical Pharmacology ( 12.3) and Clinical Studies ( 14.1)] .
The safety and efficacy of oseltamivir phosphate 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 oseltamivir phosphate for the prophylaxis of influenza in pediatric patients 1 year to 17 years old has been established [see Dosage and Administration ( 2.3), Clinical Pharmacology ( 12.3), and Clinical Studies ( 14.2)] 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 oseltamivir phosphate 75 mg taken orally once daily for 7 days in household contacts including 207 adolescents [see Clinical Studies ( 14.2)].
· 1 year to 12 years of age: Oseltamivir phosphate 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 oseltamivir phosphate for oral suspension (supplied as powder) taken orally once daily for 10 days [see Clinical Studies ( 14.2)]. 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 oseltamivir phosphate for prophylaxis of influenza have not been established for pediatric patients less than 1 year of age.
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