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These highlights do not include all the information needed to use OSELTAMIVIR PHOSPHATE CAPSULES safely and effectively. See full prescribing information for OSELTAMIVIR PHOSPHATE CAPSULES. OSELTAMIVIR PHOSPHATE Capsules, for oral use.Initial U.S. Approva | OSELTAMIVIR PHOSPHATE [A-S Medication Solutions] | BioPortfolio

13:40 EST 27th January 2019 | BioPortfolio
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Oseltamivir Phosphate Capsules, USP are 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.

Oseltamivir Phosphate Capsules, USP are indicated for the prophylaxis of influenza A and B in patients 1 year and older.

Administer oseltamivir phosphate capsules for the treatment of influenza in patients 2 weeks of age or older [ see Dosage and Administration (2.2) ] or for prophylaxis of influenza in patients 1 year and older [ see Dosage and Administration (2.3) ].

The capsules may be taken with or without food; however, tolerability may be enhanced if oseltamivir phosphate capsules are taken with food.

Adjust the oseltamivir phosphate capsules dosage in patients with moderate or severe renal impairment [ see Dosage and Administration (2.4)].

For patients who cannot swallow capsules, oseltamivir phosphate for oral suspension is the preferred formulation. When oseltamivir phosphate for oral suspension is not available from wholesaler or the manufacturer, oseltamivir phosphate capsules may be opened and mixed with sweetened liquids such as regular or sugar-free chocolate syrup, corn syrup, caramel topping, or light brown sugar (dissolved in water). During emergency situations and when neither the oral suspension or the age-appropriate strengths of oseltamivir phosphate capsules to mix with sweetened liquids are available, then a pharmacist may prepare an emergency supply of oral suspension from oseltamivir phosphate 75 mg capsules [see Dosage and Administration (2.6)] .

Initiate treatment with oseltamivir phosphate capsules within 48 hours of influenza symptom onset.

Adults and Adolescents (13 years of age and older)

The recommended oral dose of oseltamivir phosphate capsules for treatment of influenza in adults and adolescents 13 years and older is 75 mg twice daily (one 75 mg capsule twice daily) for 5 days.

Pediatric Patients (2 weeks of age through 12 years of age)

Table 1 displays the recommended oral dosage of oseltamivir phosphate for treatment of influenza in pediatric patients 2 weeks of age through 12 years of age and provides information about prescribing the capsule or the formulation for oral suspension.

Initiate post-exposure prophylaxis with oseltamivir phosphate capsules within 48 hours following close contact with an infected individual. Initiate seasonal prophylaxis with oseltamivir phosphate capsules during a community outbreak.

Adults and Adolescents (13 years of age and older)

The recommended dosage of oseltamivir phosphate capsules for prophylaxis of influenza in adults and adolescents 13 years and older is 75 mg orally once daily (one 75 mg capsule once daily) for at least 10 days following close contact with an infected individual and up to 6 weeks during a community outbreak.  In immunocompromised patients, oseltamivir phosphate capsules may be continued for up to 12 weeks [ see Use in Specific Populations (8.9) ]. The duration of protection lasts for as long as oseltamivir phosphate capsules dosing is continued.

Pediatric Patients (1 year to 12 years of age)

Table 1 displays the recommended oral dose of oseltamivir phosphate capsules for prophylaxis of influenza in pediatric patients 1 year to 12 years of age based on body weight and provides information about prescribing the capsule or the formulation for oral suspension. Prophylaxis in pediatric patients is recommended for 10 days following close contact with an infected individual and up to 6 weeks during a community outbreak [ see Use in Specific Populations (8.4) and Clinical Studies (14.2)].

Table 1 Oseltamivir Phosphate Dosage Recommendations in Pediatric Patients for Treatment and Prophylaxis of Influenza
Weight
Treatment  Dosage  for  5  days
Prophylaxis  Dosage  for  10  days The recommended duration for post-exposure prophylaxis is 10 days and the recommended duration for community out break (seasonal/pre-exposure) prophylaxis is up to 6 weeks (or up to 12 weeks in immunocompromised patients). The amount supplied (e.g., number of bottles or capsules) for seasonal prophylaxis may be greater than for post-exposure prophylaxis.
Volume  of  Oral  Suspension  ( 6  mg / mL )  for  each  Dose
Number  of  Bottles  of  Oral  Suspension  to  Dispense
Number  of  Capsules  to  Dispense  ( Strength ) 
Patients  from  2  Weeks  to  less  than  1  Year  of  Age
Any weight
3 mg/kg twice daily
Not applicable Oseltamivir phosphate for oral suspension is the preferred formulation for patients who cannot swallow capsules.
0.5 mL/kgFor patients less than 1 year of age, provide an appropriate dosing device that can accurately measure and administer small volumes.
1 bottle
Not applicable
Patients  from  1  to  12  Years  of  Age  Based  on  Body  Weight
15 kg or less
30 mg twice daily
30 mg once daily
5 mL
1 bottle
10 Capsules (30 mg)
15.1 kg to 23 kg
45 mg twice daily
45 mg once daily
7.5 mL
2 bottles
10 Capsules (45 mg)
23.1 kg to 40 kg
60 mg twice daily
60 mg once daily
10 mL
2 bottles
20 Capsules (30 mg)
40.1 kg or more
75 mg twice daily
75 mg once daily
12.5 mL
3 bottles
10 Capsules (75 mg)

Table 2 displays the dosage recommendations for the treatment and prophylaxis of influenza in adults with various stages of renal impairment (estimated creatinine clearance of less than or equal to 90 mL per minute). Dosage modifications are recommended in adults with an estimated creatinine clearance less than or equal to 60 mL per minute [ see Use in Specific Population (8.6) and Clinical Pharmacology (12.3) ].

Table 2 Recommended Dosage Modifications for Treatment and Prophylaxis of Influenza in Adults with Renal Impairment or End Stage Renal Disease (ESRD) on Dialysis
Renal  Impairment  ( Creatinine  Clearance )
Recommended 
Treatment  Regimen Capsules or oral suspension can be used for 30 mg dosing
Recommended  Prophylaxis  Regimen  Assuming three hemodialysis sessions are performed in the 5- day period. Treatment can be initiated immediately if influenza symptoms develop during the 48 hours between hemodialysis sessions; however, the post- hemodialysis dose should still be administered independently of time of administration of the initial dose. The recommended duration for post-exposure prophylaxis is at least 10 days and the recommended duration for community outbreak (seasonal/pre-exposure) prophylaxis is up to 6 weeks (or up to 12 weeks in immunocompromised patients).
Mild
(>60-90 mL/minute)
75 mg twice daily for 5 days
75 mg once daily
Moderate
(>30-60 mL/minute)
30 mg twice daily for 5 days
30 mg once daily
Severe
(>10-30 mL/minute)
30 mg once daily for 5 days
30 mg every other day
ESRD Patients on Hemodialysis 
(≤10 mL/minute)
30 mg immediately and then 30 mg after every hemodialysis cycle (treatment duration not to exceed 5 days)
30 mg immediately and then 30 mg after alternate hemodialysis cycles
ESRD Patients on Continuous Ambulatory Peritoneal DialysisData derived from studies in continuous ambulatory peritoneal dialysis (CAPD) patients. 
(≤10 mL/minute)
A single 30 mg dose administered immediately 
30 mg immediately and then 30 mg once weekly
ESRD Patients not on Dialysis
Oseltamivir phosphate capsules are not recommended
Oseltamivir phosphate capsules are not recommended

The following directions are provided for use only during emergency situations and when FDA-approved, commercially manufactured oseltamivir phosphate for oral suspension is not available from wholesalers or the manufacturer.

The following emergency preparation instructions will provide one patient with enough Oseltamivir Phosphate for a 5-day course of treatment of influenza or a 10-day course of prophylaxis of influenza.

Step #1: Determine the dosage of oseltamivir phosphate for the patient [ see Dosage and Administration (2.2 , 2.3, and 2.4) ] then determine the total volume of oral suspension needed to be prepared (see Table 3).

Step #2: Preparation must be performed with only one of the following vehicles (other vehicles have not been studied):  Cherry Syrup (Humco®), Ora- Sweet® SF (sugar-free)(Paddock Laboratories), or simple syrup. Determine the number of capsules and the amount of water and vehicle needed to prepare the total volume (see Table 3) of prepared oral suspension (6 mg per mL) for a complete treatment or prophylaxis course (see Table 4).

Step #3: Follow the instructions below for preparing the 75 mg oseltamivir phosphate capsules to produce the oral suspension (6 mg/mL):

Table 3 Emergency Preparation: Volume of Prepared Oral Suspension (6 mg per mL) Based Upon Oseltamivir Phosphate Capsules Dose
Oseltamivir  Phosphate  Dose If the oseltamivir phosphate dose is between the doses listed, use the greater listed dose to determine the total volume of prepared oral suspension.
Total  Volume  to  Prepare  per  Patient  ( mL )
15 mg or less
37.5 mL
30 mg
75 mL
45 mg
100 mL
60 mg
125 mL
75 mg
150 mL
Table 4 Emergency Preparation: Number of Oseltamivir Phosphate 75 mg Capsules and Amount of Water and Vehicle Needed to Prepare the Total Volume of a Prepared Oral Suspension (6 mg per mL)
Total  Volume  of  Prepared  Oral  Suspension 


37 . 5  mL


75  mL


100  mL


125  mL


150  mL
Number  of  Oseltamivir  Phosphate  75
mg  Capsules  ( Total  Strength )Includes overage to ensure all doses can be delivered

(225 mg)

(450 mg)

(600 mg)
10 
(750 mg)
12 
(900 mg)
Amount  of  Water
2.5 mL
5 mL
7 mL
8 mL
10 mL
Volume  of  Vehicle Cherry Syrup (Humco® ) OR
Ora-Sweet® SF (Paddock Laboratories) OR simple syrup




34.5 mL




69 mL




91 mL




115 mL




137 mL

Oseltamivir Phosphate Capsules:

Oseltamivir phosphate capsules are 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 [ see Warnings and Precautions (5.1)].

Cases of anaphylaxis and serious skin reactions including toxic epidermal necrolysis, Stevens-Johnson Syndrome, and erythema multiforme have been reported in postmarketing experience with oseltamivir phosphate capsules.  Stop oseltamivir phosphate capsules and instituteappropriate treatment if an allergic-like reaction occurs or is suspected. The use of oseltamivir phosphate capsules is contraindicated in patients with known serious hypersensitivity to oseltamivir phosphate capsules [ see Contraindications (4) and Adverse Reactions (6.2)].

There have been postmarketing reports (mostly from Japan) of delirium and abnormal behavior leading to injury, and in some cases resulting in fatal outcomes, in patients with influenza who were receiving oseltamivir phosphate capsules [ see Adverse Reactions (6.2)]. Because these events were reported voluntarily during clinical practice, estimates of frequency cannot be made but they appear to be uncommon based on oseltamivir phosphate capsules usage data. These events were reported primarily among pediatric patients and often had an abrupt onset and rapid resolution. The contribution of oseltamivir phosphate capsules 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 oseltamivir phosphate capsules-treated patients with influenza for signs of abnormal behavior. If neuropsychiatric symptoms occur, evaluate the risks and benefits of continuing oseltamivir phosphate capsules for each patient.

There is no evidence for efficacy of oseltamivir phosphate capsules 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. Oseltamivir phosphate capsules have not been shown to prevent such complications. Prescribers should be alert to the potential for secondary bacterial infections and treat them as appropriate.

The following serious adverse reactions are discussed below and elsewhere in the labeling:

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 oseltamivir phosphate 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 the otherwise healthy adults/adolescents.

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 oseltamivir phosphate given for the treatment of influenza. A total of 859 pediatric subjects received treatment with oseltamivir phosphate 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 oseltamivir phosphate (16%) compared to placebo (8%).

Amongst the 148 pediatric subjects aged 1 year to 12 years who received oseltamivir phosphate 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 oseltamivir phosphate 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 oseltamivir phosphate 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 oseltamivir phosphate 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 oseltamivir phosphate 75 mg once daily was consistent with that previously observed in other oseltamivir phosphate prophylaxis clinical trials [ see Clinical Studies (14.2)].

Table 5 Adverse Reactions Occurring in ≥1% of Adults and Adolescents (13 years of age and older) in Treatment and Prophylaxis TrialsAdverse reactions that occurred in ≥1% of oseltamivir phosphate-treated adults and adolescents and ≥1% greater in oseltamivir phosphate-treated subjects compared to placebo-treated subjects in either the treatment or prophylaxis trials.
System  Organ  Class
Treatment  Trials
Prophylaxis  Trials
Adverse  Reaction
Oseltamivir  Phosphate  75  mg  twice  daily  ( n  =  2646 )
Placebo 
( n  =  1977 )
Oseltamivir  Phosphate  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%

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)].

Pregnancy Category C 

Risk Summary

There are no adequate and well-controlled studies with oseltamivir phosphate capsules in pregnant women. Available published epidemiological data suggest that oseltamivir phosphate capsules, 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 studies, there was a dose-dependent increase in the incidence rates of a variety of minor skeletal abnormalities and variants in offspring of rats and rabbits exposed at maternally toxic doses 100 and 50 times human exposures, respectively. Oseltamivir phosphate capsules should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus [see Clinical Pharmacology (12.3)].

Clinical Considerations

Disease-A ssociated M aternal and/or E mbryo/F etal R isk

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 approximately 1500 women exposed to oseltamivir during pregnancy including approximately 400 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

Studies for effects on embryo-fetal development were conducted in rats (50, 250, and 1500 mg/kg/day) and rabbits (50, 150, and 500 mg/kg/day) by the oral route. Relative exposures at these doses were, respectively, 2, 13, and 100 times human exposure in the rat and 4, 8, and 50 times human exposure in the rabbit, based on AUC. Pharmacokinetic studies indicated that there was fetal exposure  in both species. In the rat study, minimal maternal toxicity was reported in the 1500 mg/kg/day group. In the rabbit study, slight and marked maternal toxicities were observed, respectively, in the 150 and 500 mg/kg/day groups. At the maternally toxic doses, statistically significant increases in the incidence rates of a variety of minor skeletal abnormalities and variants were observed in the exposed offspring. However, the individual incidence rate of each skeletal abnormality or variant remained within the background rates of occurrence in the species studied.

Risk Summary

Based on limited published data, oseltamivir and oseltamivir carboxylate are present in human milk at low levels considered unlikely to lead to toxicity in the breastfed infant. Exercise caution when oseltamivir phosphate capsules are administered to a nursing woman.

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:

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:

The safety and efficacy of oseltamivir phosphate for prophylaxis of influenza have not been established for pediatric patients less than 1 year of age.

Treatment of Influenza

Of the 4,765 adults in clinical trials of oseltamivir phosphate capsules for the treatment of influenza, 948 (20%) were 65 years and older, while 329 (7%) were 75 years and older. In three double-blind, placebo-controlled trials in the treatment of influenza in patients at least 65 years old, that enrolled 741 subjects (374 received placebo and 362 received oseltamivir phosphate capsules), no overall differences in safety or effectiveness were observed between these subjects and younger subjects, and other reported clinical experience has not identified differences in responses between the elderly and younger subjects [ see Clinical Studies (14.1) ].

Prophylaxis of Influenza

Of the 4,603 adults in clinical trials of oseltamivir phosphate capsules for the prophylaxis of influenza, 1,046 (23%) were 65 years and older, while 719 (16%) were 75 years and older. In a randomized, placebo-controlled trial in elderly residents of nursing homes who took oseltamivir phosphate capsules for up to 42 days for the prophylaxis of influenza (oseltamivir phosphate capsules n=276, placebo n=272), no overall differences in safety or effectiveness were observed between these subjects and younger subjects, and other reported clinical experience has not identified differences in responses between the elderly and younger subjects [ see Clinical Studies (14.2) ].

Patients with renal impairment had higher blood levels of oseltamivir carboxylate compared to patients with normal renal function which may increase the risk of oseltamivir phosphate capsules-associated adverse reactions. Therefore, dosage adjustment is recommended for patients with a serum creatinine clearance between 10 and 60 mL/minute and for patients with end-stage renal disease (ESRD) undergoing routine hemodialysis or continuous peritoneal dialysis treatment [ see Dosage and Administration (2.4)]. Oseltamivir phosphate capsules are not recommended for patients with ESRD not undergoing dialysis [ see Indications and Usage (1.3) and Clinical Pharmacology (12.3)].

No dosage adjustment is required in patients with mild to moderate hepatic impairment. The safety and pharmacokinetics in patients with severe hepatic impairment have not been evaluated [see Clinical Pharmacology (12.3)].

Efficacy of oseltamivir phosphate capsules in the treatment of influenza in patients with chronic cardiac disease and/or respiratory disease was evaluated in one randomized, placebo-controlled clinical trial.  Efficacy in this population, as measured by time to alleviation of all symptoms, was not established, but no new safety signals were identified [ see Clinical Studies (14.1) ].

No clinical trial data are available regarding treatment of influenza in patients with any medical condition sufficiently severe or unstable to be considered at imminent risk of requiring hospitalization.

Efficacy of oseltamivir phosphate capsules for the treatment or prophylaxis of influenza has not been established in immunocompromised patients [ see Clinical Studies (14.2) ]. Safety of oseltamivir phosphate capsules for prophylaxis of influenza has been demonstrated for up to 12 weeks in immunocompromised patients [ see Adverse Reactions (6.1) ].

Reports of overdoses with oseltamivir phosphate capsules 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 oseltamivir phosphate capsules [see Adverse Reactions (6)].

Oseltamivir Phosphate Capsules, USP, an influenza neuraminidase inhibitor (NAI), are available as capsules containing 30 mg, 45 mg, or 75 mg oseltamivir for oral use, in the form of oseltamivir phosphate. In addition to the active ingredient, each capsule contains pregelatinized starch, talc, povidone, croscarmellose sodium, and sodium stearyl fumarate. The 30 mg capsule shell contains gelatin, titanium dioxide, and sodium lauryl sulfate. The 45 mg  and 75 mg capsule shells contain gelatin, titanium dioxide, and sodium lauryl sulfate, FD&C Blue 1, D&C Red 28, and FD&C Red 40. Each capsule is printed with black ink, which includes black iron oxide.

Oseltamivir phosphate is a white crystalline solid with the chemical name (3R,4R,5S)-4-acetylamino-5- amino-3(1-ethylpropoxy)-1-cyclohexene-1-carboxylic acid, ethyl ester, phosphate (1:1). The chemical formula is C16H28N2O4 (free base). The molecular weight is 312.4 for oseltamivir free base and 410.4 for oseltamivir phosphate salt. The structural formula is as follows:

Oseltamivir is an antiviral drug with activity against influenza virus [see Microbiology (12.4)].

Absorption and Bioavailability

Oseltamivir is absorbed from the gastrointestinal tract after oral administration of oseltamivir phosphate and is extensively converted predominantly by hepatic esterases to oseltamivir carboxylate. At least 75% of an oral dose reaches the systemic circulation as oseltamivir carboxylate and less than 5% of the oral dose reaches the systemic circulation as oseltamivir (see Table 6).

Plasma concentrations of oseltamivir carboxylate are proportional to doses up to 500 mg given twice daily (about 6.7 times the maximum recommended oseltamivir phosphate capsules dosage) [ see Dosage and Administration (2) ]. Coadministration with food has no significant effect on the peak plasma concentration (551 ng/mL under fasted conditions and 441 ng/mL under fed conditions) and the area under the plasma concentration time curve (6218 ng·h/mL under fasted conditions and 6069 ng·h/mL under fed conditions) of oseltamivir carboxylate.

Distribution

The volume of distribution (Vss) of oseltamivir carboxylate, following intravenous administration in 24 subjects (oseltamivir phosphate is not available as an IV formulation), ranged between 23 and 26 liters.

The binding of oseltamivir carboxylate to human plasma protein is low (3%). The binding of oseltamivir to human plasma protein is 42%, which is insufficient to cause significant displacement-based drug interactions.

Elimination

Absorbed oseltamivir is primarily (>90%) eliminated by conversion to the active metabolite, oseltamivir carboxylate. Plasma concentrations of oseltamivir declined with a half-life of 1 to 3 hours in most subjects after oral administration. Oseltamivir carboxylate is not further metabolized and is eliminated in the urine. Plasma concentrations of oseltamivir carboxylate declined with a half-life of 6 to 10 hours in most subjects after oral administration.

Metabolism

Oseltamivir is extensively converted to the active metabolite, oseltamivir carboxylate, by esterases located predominantly in the liver.  Oseltamivir carboxylate is not further metabolized. Neither oseltamivir nor oseltamivir carboxylate is a substrate for, or inhibitor of, cytochrome P450 isoforms.

Excretion

Oseltamivir carboxylate 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 (via organic anion transporter) occurs in addition to glomerular filtration. Less than 20% of an oral radiolabeled dose eliminated in feces.

Specific Populations

Renal Impairment

Administration of 100 mg of oseltamivir phosphate twice daily (about 1.3 times the maximum recommended dosage) for 5 days to subjects with various degrees of renal impairment showed that exposure to oseltamivir carboxylate is inversely proportional to declining renal function.

Population-derived pharmacokinetic parameters were determined for patients with varying degrees of renal function including ESRD patients on hemodialysis. Median simulated exposures of oseltamivir carboxylate for recommended treatment and prophylaxis regimens are provided in Table 7. The pharmacokinetics of oseltamivir have not been studied in ESRD patients not undergoing dialysis [ see Indications and Usage (1.3) and Use in Specific Populations (8.6) ].

In continuous ambulatory peritoneal dialysis (CAPD) patients, the peak concentration of oseltamivir carboxylate following a single 30 mg dose of oseltamivir or once weekly oseltamivir was approximately 3-fold higher than in patients with normal renal function who received 75 mg twice daily. The plasma concentration of oseltamivir carboxylate on Day 5 (147 ng/mL) following a single 30 mg dose in CAPD patients is similar to the predicted Cmin (160 ng/mL) in patients with normal renal  function following 75 mg twice daily. Administration of 30 mg once weekly to CAPD patients resulted in plasma concentrations of oseltamivir carboxylate at the 168 hour blood sample of 63 ng/mL, which were comparable to the Cmin in patients with normal renal function receiving the approved regimen of 75 mg once daily (40 ng/mL).

Hepatic Impairment

In clinical studies oseltamivir carboxylate exposure was not altered in subjects with mild or moderate hepatic impairment [see Use in Specific Populations (8.7)].

Pregnant Women

A pooled population pharmacokinetic analysis indicates that the oseltamivir phosphate capsules dosage regimen resulted in lower exposure to the active metabolite in pregnant women (n=59) compared to non-pregnant women (n=33). However, this predicted exposure is expected to have activity against susceptible influenza virus strains and there are insufficient pharmacokinetics and safety data to recommend a dose adjustment for pregnant women [ see Use in Specific Populations (8.1) ].

Pediatric Subjects (1 year to 12 years of age)

The pharmacokinetics of oseltamivir and oseltamivir carboxylate have been evaluated in a single-dose pharmacokinetic study in pediatric subjects aged 5 to 16 years (n=18) and in a small number of pediatric subjects aged 3 to 12 years (n=5) enrolled in a clinical trial. Younger pediatric subjects cleared both the prodrug and the active metabolite faster than adult subjects resulting in a lower exposure for a given mg/kg dose. For oseltamivir carboxylate, apparent total clearance decreases linearly with increasing  age (up to 12 years). The pharmacokinetics of oseltamivir in pediatric subjects over 12 years of age are similar to those in adult subjects [ see Use in Specific Populations (8.4) ].

Pediatric Subjects (2 weeks to less than 1 year of age)

The pharmacokinetics of oseltamivir and oseltamivir carboxylate have been evaluated in two open-label studies of pediatric subjects less than one year of age (n=122) infected with influenza. Apparent clearance of the active metabolite decreases with decreasing age in subjects less than 1 year of age; however the oseltamivir and oseltamivir carboxylate exposure following a 3 mg/kg dose in subjects under 1 year of age is expected to be within the observed exposures in adults and adolescents receiving 75 mg twice daily and 150 mg twice daily [ see Use in Specific Populations (8.4) ].

Geriatric Patients

Exposure to oseltamivir carboxylate at steady-state was 25 to 35% higher in geriatric subjects (age range 65 to 78 years) compared to young adults given comparable doses of oseltamivir. Half-lives observed in the geriatric subjects were similar to those seen in young adults. Based on drug exposure and tolerability, dose adjustments are not required for geriatric patients for either treatment or prophylaxis [ see Use in Specific Populations (8.5) ].

Drug Interaction Studies

Oseltamivir is extensively converted to oseltamivir carboxylate by esterases, located predominantly in the liver. Drug interactions involving competition for esterases have not been extensively reported in literature. Low protein binding of oseltamivir and oseltamivir carboxylate suggests that the probability of drug displacement interactions is low.

In vitro studies demonstrate that neither oseltamivir nor oseltamivir carboxylate is a good substrate for P450 mixed-function oxidases or for glucuronyl transferases.

Coadministration of probenecid results in an approximate two-fold increase in exposure to oseltamivir carboxylate due to a decrease in active anionic tubular secretion in the kidney. However, due to the safety margin of oseltamivir carboxylate, no dose adjustments are required when coadministering with probenecid.

No clinically relevant pharmacokinetic interactions have been observed when coadministering oseltamivir with amoxicillin, acetaminophen, aspirin, cimetidine, antacids (magnesium and aluminum hydroxides and calcium carbonates), rimantadine, amantadine, or warfarin.

Table 6 Mean (% CV) Pharmacokinetic Parameters of Oseltamivir and Oseltamivir Carboxylate Following Multiple Dosing of 75 mg Capsules Twice Daily (n=20)
Parameter
Oseltamivir
Oseltamivir  Carboxylate
Cmax (ng/mL)
65 (26)
348 (18)
AUC0-12h (ng·h/mL)
112 (25)
2719 (20)
Table 7 Simulated Median Treatment Exposure Metrics of Oseltamivir Carboxylate in Patients with Normal Renal Function, with Renal Impairment and ESRD Patients on Hemodialysis


Renal  Function /  Impairment
Normal  Creatinine  Clearance  90 - 140
mL / min  ( n = 57 )
Mild  Creatinine  Clearance
60 - 90  mL / min  ( n = 45 )
Moderate  Creatinine  Clearance  30 - 60
mL / min  ( n = 13 )
Severe  Creatinine  Clearance
10 - 30  mL / min  ( n = 11 )
ESRD
Creatinine  Clearance  < 10  mL / min  on  Hemodialysis  ( n = 24 )
Recommended  Treatment  Regimens
PK  exposure  parameter
75  mg  twice  daily
75  mg  twice  daily
30  mg  twice  daily
30  mg  once  daily
30  mg  every  HD  cycle
Cmin (ng/mL)
145
253
180
219
221
Cmax (ng/mL)
298
464
306
477
1170
AUC48 (ng·h/mL)AUC normalized to 48 hours.
11224
18476
12008
16818
23200
Recommended  Prophylaxis   Regimens
PK  exposure  parameter
75  mg  once  daily
75  mg  once  daily
30  mg  once  daily
30  mg  every  other  day
30  mg  alternate  HD  cycle
Cmin (ng/mL)
39
62
57
70
42
Cmax (ng/mL)
213
311
209
377
903
AUC48 (ng·hr/mL)
5294
8336
6262
9317
11200

Mechanism of Action

Oseltamivir phosphate is an ethyl ester prodrug requiring ester hydrolysis for conversion to the active form, oseltamivir carboxylate. Oseltamivir carboxylate is an inhibitor of influenza virus neuraminidase affecting release of viral particles. The median IC50 values of oseltamivir against influenza A/H1N1, influenza A/H3N2, and influenza B clinical isolates were 2.5 nM (range 0.93-4.16 nM, N=74), 0.96 nM (range 0.13-7.95 nM, N=774), and 60 nM (20-285 nM, N=256), respectively, in a neuraminidase assay with a fluorescently labeled MUNANA substrate.

Antiviral Activity

The antiviral activity of oseltamivir carboxylate against laboratory strains and clinical isolates of influenza virus was determined in cell culture. The concentrations of oseltamivir carboxylate required for inhibition of influenza virus in cell culture were highly variable depending on the assay method used and the virus tested. The 50% and 90% effective concentrations (EC50 and EC90) were in the range of 0.0008 micromolar to greater than 35 micromolar and 0.004 micromolar to greater than 100 micromolar, respectively (1 micromolar =0.284 microgram per mL). The relationship between the antiviral activity in cell culture, inhibitory activity in the neuraminidase assay, and the inhibition of influenza virus replication in humans has not been established.

Resistance

Cell culture studies: Influenza A virus isolates with reduced susceptibility to oseltamivir carboxylate have been recovered by serial passage of virus in cell culture in the presence of increasing concentrations of oseltamivir carboxylate. Reduced susceptibility of influenza virus to inhibition by oseltamivir carboxylate may be conferred by amino acid substitutions in the viral neuraminidase and/or hemagglutinin proteins.

Clinical studies: Reduced susceptibility isolates have been obtained during treatment with oseltamivir and from sampling during community surveillance studies. Changes in the viral neuraminidase that have been associated with reduced susceptibility to oseltamivir carboxylate are summarized in Table 8. The clinical impact of this reduced susceptibility is unknown.

Hemagglutinin (HA) substitutions selected in cell culture and associated with reduced susceptibility to oseltamivir include (influenza virus subtype-specific numbering) A11T, K173G, and R453M in H3N2; and H99Q in influenza B virus (Yamagata lineage). In some cases, HA substitutions were selected in conjunction with known NA resistance substitutions and may contribute to reduced susceptibility to oseltamivir; however, the impact of HA substitutions on antiviral activity of oseltamivir in humans is unknown and likely to be strain-dependent.

Selection of influenza A viruses resistant to oseltamivir can occur at higher frequencies in children. The incidence of oseltamivir treatment-associated resistance in pediatric treatment studies has been detected at rates of 27 to 37% and 3 to 18% (3/11 to 7/19 and 1/34 to 9/50 post-treatment isolates, respectively) for influenza A/H1N1 and influenza A/H3N2, respectively. The frequency of resistance selection to oseltamivir and the prevalence of such resistant virus vary seasonally and geographically.

Circulating seasonal influenza strains expressing neuraminidase resistance-associated substitutions have been observed in individuals who have not received oseltamivir treatment. The oseltamivir resistance- associated substitution H275Y was found in >99% of US circulating 2008 H1N1 influenza virus isolates. The 2009 H1N1 influenza virus ("swine flu") was almost uniformly susceptible to oseltamivir; however the frequency of circulating resistant variants can change from season to season. Prescribers should consider available information from the CDC on influenza virus drug susceptibility patterns and treatment effects when deciding whether to use oseltamivir phosphate capsules.

Cross-resistance

Cross-resistance between oseltamivir and zanamivir has been observed in neuraminidase biochemical assays. The H275Y (N1 numbering) or N294S (N2 numbering) oseltamivir resistance-associated substitutions observed in the N1 neuraminidase subtype, and the E119V or N294S oseltamivir resistance-associated substitutions observed in the N2 subtype (N2 numbering), are associated with reduced susceptibility to oseltamivir but not zanamivir. The Q136K and K150T zanamivir resistance- associated substitutions observed in N1 neuraminidase, or the S250G zanamivir resistance-associated substitutions observed in influenza B virus neuraminidase, confer reduced susceptibility to zanamivir  but not oseltamivir. The R292K oseltamivir resistance-associated substitution observed in N2, and the I222T, D198E/N, R371K, or G402S oseltamivir resistance-associated substitutions observed in influenza B virus neuraminidase, confer reduced susceptibility to both oseltamivir and zanamivir. These examples do not represent an exhaustive list of cross resistance-associated substitutions and prescribers should consider available information from the CDC on influenza drug susceptibility patterns and treatment effects when deciding whether to use oseltamivir phosphate capsules.

No single amino acid substitution has been identified that could confer cross-resistance between the neuraminidase inhibitor class (oseltamivir, zanamivir) and the M2 ion channel inhibitor class (amantadine, rimantadine). However, a virus may carry a neuraminidase inhibitor-associated substitution in neuraminidase and an M2 ion channel inhibitor associated substitution in M2 and may therefore be resistant to both classes of inhibitors. The clinical relevance of phenotypic cross-resistance evaluations has not been established.

Immune Response

No influenza vaccine/oseltamivir interaction study has been conducted. In studies of naturally acquired and experimental influenza, treatment with oseltamivir phosphate capsules did not impair normal humoral antibody response to infection.

Table 8 Neuraminidase Amino Acid Substitutions Associated with Reduced Susceptibility to Oseltamivir
Amino  Acid  Substitution All numbering is N2, except where indicated
Influenza  A  N1  ( N1  numbering  in  brackets )
I117V (I117V), E119V (E119V), R152K (R152K), Y115H (Y115H), F173V (F174V), D198G/N (D199G/N), I222K/R/T/V (I223K/R/T/V), S246N (S247N), G248R+I266V (G249R+I267V), H274Y (H275Y), N294S (N295S), Q312R+I427T (Q313R+I427T), N325K (N325K), R371K (R368K)
Influenza  A  N2
E41G, E119I/V, D151V, I222L/V, Q226H, SASG245-248 deletion, S247P, R292K, N294S
Influenza  B  ( B  numbering  in  brackets )
E119A (E117A), P141S (P139S), G142R (G140R), R152K (R150K), D198E/N/Y (D197E/N/Y), I222L/T/V (I221L/T/V), A246D/S/T (A245D/S/T), H274Y (H273Y), N294S (N294S), R371K (R374K), G402S (G407S)

In 2-year carcinogenicity studies in mice and rats given daily oral doses of the prodrug oseltamivir phosphate up to 400 mg/kg and 500 mg/kg, respectively, the prodrug and the active form oseltamivir carboxylate induced no statistically significant increases in tumors over controls. The mean maximum daily exposures to the prodrug in mice and rats were approximately 130- and 320-fold, respectively, greater than those in humans at the recommended clinical dose based on AUC comparisons. The respective safety margins of the exposures to the active oseltamivir carboxylate were 15- and 50-fold.

Oseltamivir was found to be non-mutagenic in the Ames test and the human lymphocyte chromosome assay with and without enzymatic activation and negative in the mouse micronucleus test. It was found to be positive in a Syrian Hamster Embryo (SHE) cell transformation test. Oseltamivir carboxylate was non-mutagenic in the Ames test and the L5178Y mouse lymphoma assay with and without enzymatic activation and negative in the SHE cell transformation test.

In a fertility and early embryonic development study in rats, doses of oseltamivir at 50, 250, and 1500 mg/kg/day were administered to females for 2 weeks before mating, during mating and until day 6 of pregnancy. Males were dosed for 4 weeks before mating, during mating, and for 2 weeks after mating. There were no effects on fertility, mating performance or early embryonic development at any dose level. The highest dose was approximately 100 times the human systemic exposure (AUC0-24h) of oseltamivir carboxylate that occurs after administration of the maximum recommended human dose.

Adults

Two randomized, placebo-controlled double-blind clinical trials of oseltamivir phosphate capsules 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 100°F, 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 oseltamivir phosphate capsules 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 receiving oseltamivir phosphate capsules 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 oseltamivir phosphate capsules in men and women.

In the treatment of influenza, no increased efficacy was demonstrated in subjects who received higher doses of oseltamivir phosphate capsules.

Adolescents and Adults with Chronic Cardiac or Respiratory Disease

A double-blind, placebo-controlled, multicenter trial was unable to demonstrate efficacy of oseltamivir phosphate capsules (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 oseltamivir phosphate capsules 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 oseltamivir phosphate capsules  75 mg twice daily for 5 days compared to those who received placebo (p=NS) [ see Use in Specific Populations (8.5)]. 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 100°F) 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. Oseltamivir phosphate 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 oseltamivir phosphate 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 oseltamivir phosphate at doses ranging from 2 to 3.5 mg/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 oseltamivir phosphate concentrations similar to or higher than those observed in older pediatric subjects and adults receiving the approved dose and provided the basis for approval [see Adverse Reactions (6.1) and Use in Specific Populations (8.4) ].

Adult and Adolescent Subjects (13 years of age and older)

The efficacy of oseltamivir phosphate 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):

In a pooled analysis of two seasonal prophylaxis studies in healthy unvaccinated adults (aged 18 to 65 years), oseltamivir phosphate 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 oseltamivir phosphate 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 oseltamivir phosphate capsules 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 oseltamivir phosphate-treated subjects.

In the post-exposure prophylaxis trial in household contacts (aged 13 years or older) of an index influenza case, oseltamivir phosphate 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 oseltamivir phosphate capsules treatment). The incidence of laboratory-confirmed clinical influenza was 12% (24/200) in the placebo-treated subjects compared to 1% (2/205) for the oseltamivir phosphate-treated subjects.

Pediatric Subjects (1 year to 12 years of age)

The efficacy of oseltamivir phosphate 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 oseltamivir phosphate 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:

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 oseltamivir phosphate prophylaxis [3% (3/95)] compared to the group who did not receive oseltamivir phosphate prophylaxis [17% (18/106)].

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 oseltamivir phosphate group. Median time since transplant for hematopoietic stem cell transplant recipients was 424 days for the placebo group and 367 days for the oseltamivir phosphate 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 oseltamivir phosphate 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 oseltamivir phosphate 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 oseltamivir phosphate group.

Product: 50090-3718

NDC: 50090-3718-0 10 CAPSULE in a BLISTER PACK / 1 in a CARTON

Advise the patient to read the FDA-approved patient labeling (Patient Information and Instructions for Use).

Serious Skin/Hypersensitivity Reactions

Advise patients and/or caregivers of the risk of severe allergic reactions (including anaphylaxis) or serious skin reactions. Instruct patients and/or caregivers to stop oseltamivir phosphate capsules and seek immediate medical attention if an allergic-like reaction occurs or is suspected [ see Warnings and Precautions (5.1)].

Neuropsychiatric Events

Advise patients and/or caregivers of the risk of neuropsychiatric events in oseltamivir phosphate capsules-treated patients with influenza and instruct patients to contact their physician if they experience signs of abnormal behavior while receiving oseltamivir phosphate capsules [ see Warnings and Precautions (5.2)].

Important Dosing Information

Instruct patients to begin treatment with oseltamivir phosphate capsules as soon as possible from the first appearance of flu symptoms, within 48 hours of onset of symptoms. Similarly, instruct patients to start taking oseltamivir phosphate capsules for  prevention as soon as possible after exposure [ see Dosage and Administration (2)].

Instruct patients to take any missed doses as soon as they remember, except if it is near the next scheduled dose (within 2 hours), and then continue to take oseltamivir phosphate capsules at the usual times.

Influenza Vaccines

Instruct patients that oseltamivir phosphate capsules are not a substitute for receiving an annual flu vaccination. Patients should continue receiving an annual flu vaccination according to guidelines on immunization practices. Because of the potential for oseltamivir phosphate capsules to inhibit replication of live attenuated influenza vaccine (LAIV) and possibly reduce efficacy of LAIV, avoid administration of LAIV within 2 weeks or 48 hours after oseltamivir phosphate capsules administration, unless medically necessary [ see Drug Interactions (7.1) ].

Oseltamivir Phosphate Capsules, USP

Manufactured by:

Nesher Pharmaceuticals USA LLC.

St. Louis, MO 63044

Distributed by:

Zydus Pharmaceuticals USA Inc. 

Pennington, NJ 08534

P10268-3

Rev. 12 /2016

PATIENT INFORMATION

Oseltamivir P hosphate Capsules USP , for oral use (os-el-TAM-ih-veer)

What are Oseltamivir Phosphate Capsules?

Oseltamivir phosphate capsules are a prescription medicine used to:

It is not known if oseltamivir phosphate capsules are:

Oseltamivir phosphate capsules do not treat or prevent illness that is caused by infections other than the influenza virus.

Oseltamivir phosphate capsules do not prevent bacterial infections that may happen with the flu.

Oseltamivir phosphate capsules are not recommended for people with end-stage renal disease (ESRD) who are not receiving dialysis.

Oseltamivir p hosphate c apsules do not take the place of receiving a flu vaccination. Talk to your healthcare provider about when you should receive an annual flu vaccination.

Who should not take o seltamivir p hosphate c apsules?

Do not take oseltamivir phosphate capsules if you are allergic to oseltamivir phosphate or any of the ingredients in oseltamivir phosphate capsules. See the end of this leaflet for a complete list of ingredients in o seltamivir p hosphate c apsules.

What should I tell my healthcare provider before taking o seltamivir p hosphate c apsules?

Before you take o seltamivir p hosphate c apsules, tell your healthcare provider if you:

Tell your healthcare provider about all the medicines you take, including prescription or over-the- counter medicines, vitamins, and herbal supplements.

Know the medicines you take. Keep a lis t of them to show your healthcare provider and pharmacist when you get a new medicine.

How should I take Oseltamivir Phosphate Capsules?

What are the possible  side effects of o seltamivir p hosphate c apsules?

Oseltamivir phosphate capsules may cause serious side effects, including:

The most common side effects of oseltamivir phosphate capsules when used for treatment of the flu include nausea, vomiting, and headache.

The most common side effect of oseltamivir phosphate capsules when used for prevention of the flu include nausea, vomiting, headache, and pain.

Tell your healthcare provider if you have any side effect that bothers you or that does not go away. These are not all of the possible side effects of oseltamivir phosphate capsules.

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800- FDA-1088.

How should I store Oseltamivir Phosphate Capsules?

Keep o seltamivir p hosphate c apsules and all medicines out of the reach of children.

General information about the safe and effective use of Oseltamivir Phosphate Capsules.

Medicines are sometimes prescribed for purposes other than those listed in a Patient Information leaflet. Do not use oseltamivir phosphate capsules for a condition for which it was not prescribed. Do not give oseltamivir phosphate capsules to other people, even if they have the same symptoms you have. It may harm them.

If you would like more information, talk with your healthcare provider. You can ask your healthcare provider or pharmacist for information about oseltamivir phosphate capsules that is written for health professionals. For more information, contact Zydus Pharmaceuticals at 1-877-993-8779.

What are the ingredients in Oseltamivir Phosphate Capsules?

Active ingredient: oseltamivir phosphate

Inactive ingredients:

Oseltamivir p hosphate c apsules: pregelatinized starch, talc, povidone, croscarmellose sodium, and sodium stearyl fumarate

30mg capsule shell: gelatin, titanium dioxide, and sodium lauryl sulfate

45mg capsules shell: gelatin, titanium dioxide, and sodium lauryl sulfate, FD&C Blue 1, D&C Red 28, and FD&C Red 40

75mg capsules shell: gelatin, titanium dioxide, and sodium lauryl sulfate, FD&C Blue 1, D&C Red 28, and FD&C Red 40

Manufactured by:

Nesher Pharmaceuticals USA LLC.

St. Louis, MO 63044

Distributed by:

Zydus Pharmaceuticals USA Inc.

Pennington, NJ 08534

This Patient Information has been approved by the U.S. Food and Drug Administration.

Revised 12/2016

INSTRUCTIONS FOR USE

Oseltamivir phosphate capsules, USP , for oral use (os-el-TAM-ih-veer)

How do I mix the contents of o seltamivir p hosphate c apsules with sweetened liquids, if directed by my healthcare provider?

You will need:

Step 1. Open the contents of the prescribed dose of oseltamivir phosphate capsules into a small bowl.

Step 2. Add a small amount of the sweetened liquid to the capsule contents.

Step 3. Stir the mixture and give the entire dose of oseltamivir phosphate.

This Instructions for Use have been approved by the U.S. Food and Drug Administration.

P10268-3

Rev. 12/2016

Manufacturer

A-S Medication Solutions

Active Ingredients

Source

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PubMed Articles [1360 Associated PubMed Articles listed on BioPortfolio]

Furan Derived Chiral Bicycloaziridino Lactone Synthon: Collective Syntheses of Oseltamivir Phosphate (Tamiflu), (S)-Pipecolic acid and its 3-Hydroxy Derivatives.

The unified synthetic strategy for oseltamivir phosphate (tamiflu), ( S )-pipecolic acid and its 3-hydroxy derivatives from furan derived common chiral bicycloaziridino lactone synthon is described he...

Discovery of novel "Dual-site" binding oseltamivir derivatives as potent influenza virus neuraminidase inhibitors.

From our research group, it was noticed that oseltamivir derivatives targeting 150-cavity of neuraminidase enzyme (NA) could significantly increase antiviral activity. Thus, we further enriched the C5...

Effect of Oral Oseltamivir on Virological Outcomes in Low-risk Adults With Influenza: A Randomized Clinical Trial.

Duration of viral shedding is a determinant of infectivity and transmissibility, but few data exist about oseltamivir's ability to alter viral shedding.

Discovery of novel 1,2,3-triazole oseltamivir derivatives as potent influenza neuraminidase inhibitors targeting the 430-cavity.

A novel series of 1,2,3-triazole oseltamivir derivatives, which could simultaneously occupy the classical NA catalytic site and the newly reported 430-cavity, were designed, synthesized, and evaluated...

Novel N-Substituted oseltamivir derivatives as potent influenza neuraminidase inhibitors: Design, synthesis, biological evaluation, ADME prediction and molecular docking studies.

The discovery of novel potent neuraminidase (NA) inhibitors remains an attractive approach for treating infectious diseases caused by influenza. In this study, we describe the design and synthesis of ...

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