RELENZA zanamivir 5 mg Powder
🆔 Identity & classification
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🏷️ RxNorm drug class
This medicine belongs to the Neuraminidase Inhibitor class.
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🏭 Manufacturer & labeler
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🩺 Clinical
- Relenza comes as an inhalation powder, not a pill. You breathe it in using a small device called a DISKHALER, which delivers the medicine directly to your airways and lungs — exact...
- How is Relenza different from a regular flu pill? Why do I have to inhale it?
- Relenza is generally not recommended for people with asthma or COPD. There's a real risk of a sudden, serious airway spasm called bronchospasm, and some cases have been fatal. Rele...
- I have asthma — can I still use Relenza?
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🧪 Inactive Ingredients / Excipients
Inactive ingredients, also called excipients, are components of the drug product other than the active ingredient. They may include fillers, dyes, coatings, preservatives, flavors, or other formulation ingredients.
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UNII J2B2A4N98G
Lactose is a natural sugar derived from milk. In medications, it serves as a filler and binder to add bulk and help hold tablet or capsule ingredients together during manufacturing.
1 inactive ingredient listed in the exact product block matched to this NDC.
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ingredient classCode="IACT" elements from the exact product block matched by this NDC. Label-section narrative from DailyMed / the openFDA label index is shown separately when available.Inactive ingredient FAQ
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💲 Pricing
A drug doesn't have one price. Each row is a different public payment system, and none is what you'd pay at the counter — that depends on your insurance. The ⓘ on each row explains what it measures.
| Price system | Per g | Per package |
|---|---|---|
| Retail pharmacies payNADAC · weekly | Not in the retail survey — common for institutional, discontinued, or low-volume packs. | |
| Medicaid paysCMS SDUD · 12 mo | No recent Medicaid claims on file for this NDC — rare and low-volume NDCs are suppressed in the public data. | |
| Medicare drug plans payPart D · Q2 2026 | $2.95 | — |
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🔁 Therapeutic equivalents
| Product | Labeler | Pack | NADAC/unit | TE | Status | Price vs. this |
|---|---|---|---|---|---|---|
| Relenza 5 mgthis 00173-0681-22 | GlaxoSmithKline | 4 powders | — | — | FDA listed | — |
| Relenza 5 mg 50090-8016-00 | A-S | 4 powders | — | — | FDA listed | — |
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⏳ Availability & generic status
We did not find an FDA-approved generic match for this exact strength, form and route.
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📊 Medicare Part D spend CMS · PART D · 2026 (Q1)
🔬 Reported adverse events (FAERS)
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📦 Packaging — all sizes for this product
| Package NDC | Description | Per unit | Per pack | Marketing start | Status |
|---|---|---|---|---|---|
| 00173-0681-01 | 5 PACKAGE in 1 CARTON (0173-0681-01) / 4 POWDER in 1 PACKAGE | $2.83 / ea | $56.64 | 1999-09-22 | Active |
| 00173-0681-22 You're viewing this | 5 PACKAGE in 1 CARTON (0173-0681-22) / 4 POWDER in 1 PACKAGE | — | — | 2007-03-09 | Active |
Pack size FAQ
What quantity is in NDC 00173-0681-22?
What NDC number is used to bill for this package of RELENZA zanamivir 5 mg Powder?
Prices are the latest CMS NADAC pharmacy acquisition cost per NDC; per-pack figures are per-unit × pack quantity, shown only when the pack is denominated in the same measure NADAC prices.
🧭 About this NDC listing & data coverage
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| NDC identity (package / product / labeler codes) | ✓ Available |
| Labeler | ✓ Available |
| Product & package description | ✓ Available |
| Marketing category & status | ✓ Available |
| Active ingredient / dosage form / route | ✓ Available |
| FDA label (SPL via DailyMed) | ✓ Available |
| Package photos | ✓ Available |
| Inactive ingredients (structured) | ✓ Available |
| NADAC pharmacy acquisition price (CMS) | — Not published for this NDC CMS publishes NADAC only for NDCs reported in its retail-pharmacy survey. |
| Orange Book / therapeutic-equivalence data | — Not published for this NDC Applies only to products approved under an NDA/ANDA; many listings are out of scope. |
| HCPCS J-code billing crosswalk | — Not published for this NDC Most self-administered / retail products have no J-code — that is normal. |
| Medicaid utilization (CMS SDUD) | — Not published for this NDC CMS reports utilization only for NDCs with Medicaid claims above its privacy threshold. |
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📄 Full prescribing information FDA SPL
🎯 Indications and Usage ▾
1 INDICATIONS AND USAGE RELENZA, an influenza virus neuraminidase inhibitor (NAI), is indicated for: Treatment of acute, uncomplicated influenza type A and B infections in patients aged 7 years and older who have been symptomatic for no more than 2 days. ( 1.1 ) Prophylaxis of influenza in patients aged 5 years and older. ( 1.2 ) Important Limitations of Use: Not recommended for treatment or prophylaxis of influenza in: • Individuals with underlying airways disease.
( 5.1 ) Not proven effective for: • Treatment in individuals with underlying airways disease. ( 1.3 ) • Prophylaxis in nursing home residents. ( 1.3 ) Not a substitute for annual influenza vaccination.
( 1.3 ) Consider available information on influenza drug susceptibility patterns and treatment effects when deciding whether to use RELENZA. ( 1.3 )
1.1Treatment of Influenza RELENZA (zanamivir) inhalation powder is indicated for treatment of uncomplicated acute illness due to influenza A and B virus in adults and pediatric patients aged 7 years and older who have been symptomatic for no more than 2 days.
1.2Prophylaxis of Influenza RELENZA is indicated for prophylaxis of influenza in adults and pediatric patients aged 5 years and older.
1.3Important Limitations of Use • RELENZA is not recommended for treatment or prophylaxis of influenza in individuals with underlying airways disease (such as asthma or chronic obstructive pulmonary disease) due to risk of serious bronchospasm [see Warnings and Precautions ( 5.1 )] . • RELENZA has not been proven effective for treatment of influenza in individuals with underlying airways disease. • RELENZA has not been proven effective for prophylaxis of influenza in the nursing home setting. • RELENZA is not a substitute for early influenza vaccination on an annual basis as recommended by the Centers for Disease Control's Immunization Practices Advisory Committee. • Influenza viruses change over time.
Emergence of resistance mutations 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 RELENZA. • There is no evidence for efficacy of zanamivir in any illness caused by agents other than influenza virus A and B. • Patients should be advised that the use of RELENZA for treatment of influenza has not been shown to reduce the risk of transmission of influenza to others.
⏱️ Dosage and Administration ▾
2 DOSAGE AND ADMINISTRATION Indication Dose Treatment of Influenza ( 2.2 ) 10 mg twice daily for 5 days Prophylaxis: ( 2.3 ) Household Setting 10 mg once daily for 10 days Community Outbreaks 10 mg once daily for 28 days Note: The 10-mg dose is provided by 2 inhalations (one 5-mg blister per inhalation). ( 2.1 )
2.1Dosing Considerations • RELENZA is for administration to the respiratory tract by oral inhalation only , using the DISKHALER device provided [see Warnings and Precautions ( 5.6 )] . • The 10-mg dose is provided by 2 inhalations (one 5-mg blister per inhalation). • Patients should be instructed in the use of the delivery system. Instructions should include a demonstration whenever possible. If RELENZA is prescribed for children, it should be used only under adult supervision and instruction, and the supervising adult should first be instructed by a healthcare professional [see Patient Counseling Information ( 17 )] . • Patients scheduled to use an inhaled bronchodilator at the same time as RELENZA should use their bronchodilator before taking RELENZA [see Patient Counseling Information ( 17 )] .
2.2Treatment of Influenza • The recommended dose of RELENZA for treatment of influenza in adults and pediatric patients aged 7 years and older is 10 mg twice daily (approximately 12 hours apart) for 5 days. • Two doses should be taken on the first day of treatment whenever possible provided there is at least 2 hours between doses. • On subsequent days, doses should be about 12 hours apart (e.g., morning and evening) at approximately the same time each day. • The safety and efficacy of repeated treatment courses have not been studied.
2.3Prophylaxis of Influenza Household Setting • The recommended dose of RELENZA for prophylaxis of influenza in adults and pediatric patients aged 5 years and older in a household setting is 10 mg once daily for 10 days. • The dose should be administered at approximately the same time each day. • There are no data on the effectiveness of prophylaxis with RELENZA in a household setting when initiated more than 1.5 days after the onset of signs or symptoms in the index case. Community Outbreaks • The recommended dose of RELENZA for prophylaxis of influenza in adults and adolescents in a community setting is 10 mg once daily for 28 days. • The dose should be administered at approximately the same time each day. • There are no data on the effectiveness of prophylaxis with RELENZA in a community outbreak when initiated more than 5 days after the outbreak was identified in the community. • The safety and effectiveness of prophylaxis with RELENZA have not been evaluated for longer than 28 days’ duration.
💊 Dosage Forms and Strengths ▾
3 DOSAGE FORMS AND STRENGTHS Blister for oral inhalation: 5 mg. Four 5-mg blisters of powder on a ROTADISK for oral inhalation via DISKHALER. Packaged in carton containing 5 ROTADISKs (total of 10 doses) and 1 DISKHALER inhalation device [see How Supplied/Storage and Handling ( 16 )] .
Blister for oral inhalation: 5 mg. Four 5-mg blisters of powder on a ROTADISK for oral inhalation via DISKHALER. Packaged in carton containing 5 ROTADISKs (total of 10 doses) and 1 DISKHALER inhalation device.
( 3 )
⛔ Contraindications ▾
4 CONTRAINDICATIONS RELENZA is contraindicated in patients with history of allergic reaction to any ingredient of RELENZA, including milk proteins [see Warnings and Precautions ( 5.2 ), Description ( 11 )] . Do not use in patients with history of allergic reaction to any ingredient of RELENZA, including milk proteins. ( 4 )
⚠️ Warnings and Cautions ▾
5 WARNINGS AND PRECAUTIONS • Bronchospasm: Serious, sometimes fatal, cases have occurred. Not recommended in individuals with underlying airways disease. Discontinue RELENZA if bronchospasm or decline in respiratory function develops.
( 5.1 ) • Allergic Reactions: Discontinue RELENZA and initiate appropriate treatment if an allergic reaction occurs or is suspected. ( 5.2 ) • Neuropsychiatric Events: Patients with influenza, particularly pediatric patients, may be at an increased risk of seizures, confusion, or abnormal behavior early in their illness. Monitor for signs of abnormal behavior.
( 5.3 ) • High-Risk Underlying Medical Conditions: Safety and effectiveness have not been demonstrated in these patients. ( 5.4 )
5.1Bronchospasm RELENZA is not recommended for treatment or prophylaxis of influenza in individuals with underlying airways disease (such as asthma or chronic obstructive pulmonary disease). Serious cases of bronchospasm, including fatalities, have been reported during treatment with RELENZA in patients with and without underlying airways disease. Many of these cases were reported during postmarketing and causality was difficult to assess.
RELENZA should be discontinued in any patient who develops bronchospasm or decline in respiratory function; immediate treatment and hospitalization may be required. Some patients without prior pulmonary disease may also have respiratory abnormalities from acute respiratory infection that could resemble adverse drug reactions or increase patient vulnerability to adverse drug reactions. Bronchospasm was documented following administration of zanamivir in 1 of 13 subjects with mild or moderate asthma (but without acute influenza‑like illness) in a Phase 1 trial.
In a Phase 3 trial in subjects with acute influenza‑like illness superimposed on underlying asthma or chronic obstructive pulmonary disease, 10% (24 of 244) of subjects on zanamivir and 9% (22 of 237) on placebo experienced a greater than 20% decline in forced expiratory volume in 1 second (FEV 1 ) following treatment for 5 days. If use of RELENZA is considered for a patient with underlying airways disease, the potential risks and benefits should be carefully weighed. If a decision is made to prescribe RELENZA for such a patient, this should be done only under conditions of careful monitoring of respiratory function, close observation, and appropriate supportive care, including availability of fast‑acting bronchodilators.
5.2Allergic Reactions Allergic-like reactions, including oropharyngeal edema, serious skin rashes, and anaphylaxis have been reported in postmarketing experience with RELENZA. RELENZA should be stopped and appropriate treatment instituted if an allergic reaction occurs or is suspected.
5.3Neuropsychiatric Events Influenza can be associated with a variety of neurologic and behavioral symptoms which can include events such as seizures, 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. There have been postmarketing reports of delirium and abnormal behavior leading to injury in patients with influenza who were receiving neuraminidase inhibitors (NAIs), including RELENZA.
Because these events were reported voluntarily during clinical practice, estimates of frequency cannot be made, but they appear to be uncommon based on usage data for RELENZA. These events were reported primarily among pediatric patients and often had an abrupt onset and rapid resolution. The contribution of RELENZA to these events has not been established.
Patients with influenza should be closely monitored for signs of abnormal behavior. If neuropsychiatric symptoms occur, the risks and benefits of continuing treatment should be evaluated for each patient.
5.4Limitations of Populations Studied Safety and efficacy have not been demonstrated in patients with high-risk underlying me…
🤒 Adverse Reactions ▾
6 ADVERSE REACTIONS The following adverse reactions are discussed in greater detail in other sections of the labeling: • Bronchospasm [see Warnings and Precautions ( 5.1 )] . • Safety information in patients with underlying airways disease [see Warnings and Precautions ( 5.1 )]. • Allergic-like reactions [see Warnings and Precautions ( 5.2 )] . The most common adverse events reported in greater than 1.5% of subjects treated with RELENZA and more commonly than in subjects treated with placebo are: • Treatment Trials – sinusitis, dizziness.
( 6.1 ) • Prophylaxis Trials – fever and/or chills, arthralgia, and articular rheumatism. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact GlaxoSmithKline at 1-888-825-5249 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch .
6.1Clinical 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 with rates in the clinical trials of another drug and may not reflect the rates observed in practice. The placebo used in clinical trials consisted of inhaled lactose powder, which is also the vehicle for the active drug; therefore, some adverse events occurring at similar frequencies in different treatment groups could be related to lactose vehicle inhalation.
Treatment of Influenza Clinical Trials in Adults and Adolescents: Adverse events that occurred with an incidence greater than or equal to 1.5% in treatment trials are listed in Table 1. This table shows adverse events occurring in subjects aged 12 years and older receiving RELENZA 10 mg inhaled twice daily, RELENZA in all inhalation regimens, and placebo inhaled twice daily (where placebo consisted of the same lactose vehicle used in RELENZA). Table 1.
Summary of Adverse Events ≥1.5% Incidence during Treatment in Adults and Adolescents a Includes trials where RELENZA was administered intranasally (6.4 mg 2 to 4 times per day in addition to inhaled preparation) and/or inhaled more frequently (q.i.d.) than the currently recommended dose. Adverse Event RELENZA Placebo (Lactose Vehicle) (n = 1,520) 10 mg b.i.d. Inhaled (n = 1,132) All Dosing Regimens a (n = 2,289) Body as a whole Headaches 2% 2% 3% Digestive Diarrhea 3% 3% 4% Nausea 3% 3% 3% Vomiting 1% 1% 2% Respiratory Nasal signs and symptoms 2% 3% 3% Bronchitis 2% 2% 3% Cough 2% 2% 3% Sinusitis 3% 2% 2% Ear, nose, and throat infections 2% 1% 2% Nervous system Dizziness 2% 1% <1% Additional adverse reactions occurring in less than 1.5% of subjects receiving RELENZA included malaise, fatigue, fever, abdominal pain, myalgia, arthralgia, and urticaria.
The most frequent laboratory abnormalities in Phase 3 treatment trials included elevations of liver enzymes and creatine phosphokinase (CPK), lymphopenia, and neutropenia. These were reported in similar proportions of zanamivir and lactose vehicle placebo recipients with acute influenza‑like illness. Clinical Trials in Pediatric Subjects: Adverse events that occurred with an incidence greater than or equal to 1.5% in children receiving treatment doses of RELENZA in 2 Phase 3 trials are listed in Table 2 .
This table shows adverse events occurring in pediatric subjects aged 5 to 12 years receiving RELENZA 10 mg inhaled twice daily and placebo inhaled twice daily (where placebo consisted of the same lactose vehicle used in RELENZA). Table 2. Summary of Adverse Events ≥1.5% Incidence during Treatment in Pediatric Subjects a a Includes a subset of subjects receiving RELENZA for treatment of influenza in a prophylaxis trial.
Adverse Event RELENZA 10 mg b.i.d. Inhaled (n = 291) Placebo (Lactose Vehicle) (n = 318) Respiratory Ear, nose, and throat infections 5% 5% Ear, nose, and throat hemorrhage <1% 2% Asthma <1% 2% Cough <1% 2% Digestive Vomiting 2% 3% Diarrhea 2% 2% Nausea <1% 2% In 1 of the 2 trials described in Table 2 , some additional information is available from children (aged 5 to 12 years) without acute influenza-like il…
🔄 Drug Interactions ▾
7 DRUG INTERACTIONS The concurrent use of RELENZA with live attenuated influenza vaccine (LAIV) intranasal has not been evaluated. However, because of potential interference between these products, LAIV should not be administered within 2 weeks before or 48 hours after administration of RELENZA, unless medically indicated. The concern about possible interference arises from the potential for antiviral drugs to inhibit replication of live vaccine virus.
Trivalent inactivated influenza vaccine can be administered at any time relative to use of RELENZA [see Microbiology ( 12.4 )] . Live attenuated influenza vaccine, intranasal ( 7 ): • Do not administer until 48 hours following cessation of RELENZA. • Do not administer RELENZA until 2 weeks following administration of the live attenuated influenza vaccine, unless medically indicated.
👥 Use in Specific Populations ▾
8 USE IN SPECIFIC POPULATIONS
8.1Pregnancy Risk Summary Available data from published studies suggest that use of RELENZA during pregnancy is not associated with an increased risk of birth defects or adverse maternal or fetal outcomes. However, these studies are limited by their small sample sizes, which preclude a definitive assessment of the risk (see Data). There are risks to the mother and fetus associated with influenza infection in pregnancy (see Clinical Considerations) .
In animal reproduction studies, no adverse developmental effects were observed with intravenous or subcutaneous administration of zanamivir at exposures 300 and 150 times, respectively, the systemic exposure at the maximum recommended human inhalation dose (MRHID) of 10 mg twice daily (see Data) . The background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes.
In the U.S. general population, the background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 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, stillbirths, birth defects, preterm delivery, low birth weight, and small for gestational age. Data Human Data: A study of population-based registers from Denmark, Norway, Sweden, and France reported outcomes of 5,824 pregnant women who filled a prescription for an NAI compared with outcomes in unexposed pregnant women in the general population.
This study included 1,560 women who filled a prescription for zanamivir (including 321 first trimester exposures). Although no specific analyses were conducted for zanamivir, exposure to the NAI class in utero was not associated with major birth defects, preterm birth, low birth weight, small for gestational age, still birth, neonatal morbidity, or neonatal mortality. A few published studies compared outcomes of pregnant women exposed to zanamivir with outcomes in various comparator cohorts.
These studies suggested no increased risk of major birth defects, preterm birth, or low birth weight. Sample sizes in these studies ranged from 50 to 180 pregnant women exposed to zanamivir, including 15 to 44 women exposed in the first trimester. Limitations of available studies include the lack of specific analyses for zanamivir, possible exposure and outcome misclassification, and small sample sizes.
These limitations preclude a definitive assessment of the risk. Animal Data: Zanamivir was administered intravenously to pregnant rats and rabbits at 1, 9, or 90 mg/kg/day during organogenesis (gestation Day 6 to 15 [rat] and 7 to 19 [rabbit]). No adverse maternal or embryo-fetal effects were observed up to the highest intravenous dose of zanamivir (90 mg/kg/day), resulting in systemic drug exposure (AUC) estimated from both rats and rabbits, 300 times the exposure at the MRHID.
In a separate study, zanamivir was administered subcutaneously to pregnant rats at 3, 27, and 240 mg/kg/day in three divided doses during organogenesis (gestation Day 7 to 17). An increased incidence of skeletal and visceral alterations and variants was observed at the high dose (240 mg/kg/day). No adverse maternal or embryo-fetal effects were observed at the middle dose (27 mg/kg/day), resulting in systemic drug exposure (AUC) 150 times the exposure at the MRHID.
In prenatal and postnatal development studies in rats, zanamivir was administered intravenously at 1, 9, or 90 mg/kg/day during organogenesis (gestation Day 0 to 19) or from late gestation through delivery and lactation (gestation Day 16 to post-partum/lactation Day 21). No significant effects were observed in the offspring at systemic drug exposures (AUC) estimated to be 300 times the exposure at the MRHID. Zan…
🤰 Pregnancy ▾
8.1Pregnancy Risk Summary Available data from published studies suggest that use of RELENZA during pregnancy is not associated with an increased risk of birth defects or adverse maternal or fetal outcomes. However, these studies are limited by their small sample sizes, which preclude a definitive assessment of the risk (see Data). There are risks to the mother and fetus associated with influenza infection in pregnancy (see Clinical Considerations) .
In animal reproduction studies, no adverse developmental effects were observed with intravenous or subcutaneous administration of zanamivir at exposures 300 and 150 times, respectively, the systemic exposure at the maximum recommended human inhalation dose (MRHID) of 10 mg twice daily (see Data) . The background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes.
In the U.S. general population, the background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 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, stillbirths, birth defects, preterm delivery, low birth weight, and small for gestational age. Data Human Data: A study of population-based registers from Denmark, Norway, Sweden, and France reported outcomes of 5,824 pregnant women who filled a prescription for an NAI compared with outcomes in unexposed pregnant women in the general population.
This study included 1,560 women who filled a prescription for zanamivir (including 321 first trimester exposures). Although no specific analyses were conducted for zanamivir, exposure to the NAI class in utero was not associated with major birth defects, preterm birth, low birth weight, small for gestational age, still birth, neonatal morbidity, or neonatal mortality. A few published studies compared outcomes of pregnant women exposed to zanamivir with outcomes in various comparator cohorts.
These studies suggested no increased risk of major birth defects, preterm birth, or low birth weight. Sample sizes in these studies ranged from 50 to 180 pregnant women exposed to zanamivir, including 15 to 44 women exposed in the first trimester. Limitations of available studies include the lack of specific analyses for zanamivir, possible exposure and outcome misclassification, and small sample sizes.
These limitations preclude a definitive assessment of the risk. Animal Data: Zanamivir was administered intravenously to pregnant rats and rabbits at 1, 9, or 90 mg/kg/day during organogenesis (gestation Day 6 to 15 [rat] and 7 to 19 [rabbit]). No adverse maternal or embryo-fetal effects were observed up to the highest intravenous dose of zanamivir (90 mg/kg/day), resulting in systemic drug exposure (AUC) estimated from both rats and rabbits, 300 times the exposure at the MRHID.
In a separate study, zanamivir was administered subcutaneously to pregnant rats at 3, 27, and 240 mg/kg/day in three divided doses during organogenesis (gestation Day 7 to 17). An increased incidence of skeletal and visceral alterations and variants was observed at the high dose (240 mg/kg/day). No adverse maternal or embryo-fetal effects were observed at the middle dose (27 mg/kg/day), resulting in systemic drug exposure (AUC) 150 times the exposure at the MRHID.
In prenatal and postnatal development studies in rats, zanamivir was administered intravenously at 1, 9, or 90 mg/kg/day during organogenesis (gestation Day 0 to 19) or from late gestation through delivery and lactation (gestation Day 16 to post-partum/lactation Day 21). No significant effects were observed in the offspring at systemic drug exposures (AUC) estimated to be 300 times the exposure at the MRHID. Zanamivir distributed across the…
🧒 Pediatric Use ▾
8.4Pediatric Use Treatment of Influenza Safety and effectiveness of RELENZA for treatment of influenza have not been assessed in pediatric patients younger than 7 years, but were studied in a Phase 3 treatment trial in pediatric subjects, where 471 children aged 5 to 12 years received zanamivir or placebo [see Clinical Studies ( 14.1 )] . Adolescents were included in the 3 principal Phase 3 adult treatment trials. In these trials, 67 patients were aged 12 to 16 years.
No definite differences in safety and efficacy were observed between these adolescent patients and young adults. In a Phase 1 trial of 16 children aged 6 to 12 years with signs and symptoms of respiratory disease, 4 did not produce a measurable peak inspiratory flow rate (PIFR) through the DISKHALER (3 with no adequate inhalation on request, 1 with missing data), 9 had measurable PIFR on each of 2 inhalations, and 3 achieved measurable PIFR on only 1 of 2 inhalations. Neither of two 6-year-olds and one of two 7-year-olds produced measurable PIFR.
Overall, 8 of the 16 children (including all those younger than 8 years) either did not produce measurable inspiratory flow through the DISKHALER or produced peak inspiratory flow rates below the 60 L/minute considered optimal for the device under standardized in vitro testing; lack of measurable flow rate was related to low or undetectable serum concentrations [see Clinical Pharmacology ( 12.3 ), Clinical Studies ( 14.1 )] . Prescribers should carefully evaluate the ability of young children to use the delivery system if prescription of RELENZA is considered.
Prophylaxis of Influenza The safety and effectiveness of RELENZA for prophylaxis of influenza have been studied in 4 Phase 3 trials where 273 children aged 5 to 11 years and 239 adolescents aged 12 to 16 years received RELENZA. No differences in safety and effectiveness were observed between pediatric and adult subjects [see Clinical Studies ( 14.2 )] .
🧓 Geriatric Use ▾
8.5Geriatric Use Of the total number of subjects in 6 clinical trials of RELENZA for treatment of influenza, 59 subjects were aged 65 years and older, while 24 subjects were aged 75 years and older. Of the total number of subjects in 4 clinical trials of RELENZA for prophylaxis of influenza in households and community settings, 954 subjects were aged 65 years and older, while 347 subjects were aged 75 years and older. 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, but greater sensitivity of some older individuals cannot be ruled out.
Elderly patients may need assistance with use of the device. In 2 additional trials of RELENZA for prophylaxis of influenza in the nursing home setting, efficacy was not demonstrated [see Indications and Usage ( 1.3 )] .
🆘 Overdosage ▾
10 OVERDOSAGE Reports of overdosage from administration of RELENZA have been received during postmarketing experience. The reported clinical signs or symptoms were similar to those observed with therapeutic doses of RELENZA and the underlying disease. As zanamivir has a low molecular weight, low protein binding, and small volume of distribution, it is expected to be removed by hemodialysis.
🧬 Clinical Pharmacology ▾
12 CLINICAL PHARMACOLOGY
12.1Mechanism of Action Zanamivir is an antiviral drug with activity against influenza virus [see Microbiology ( 12.4 )] .
12.2Pharmacodynamics Cardiac Electrophysiology In a thorough QT/QTc study in 40 healthy subjects, intravenous zanamivir 600 mg and 1,200 mg (60 and 120 times the dose in RELENZA) had no effect on the QTc interval and did not prolong the PR interval.
12.3Pharmacokinetics Absorption and Bioavailability Pharmacokinetic studies of orally inhaled zanamivir indicate that approximately 4% to 17% of the inhaled dose is systemically absorbed. The peak serum concentrations ranged from 17 to 142 ng/mL within 1 to 2 hours following a 10‑mg dose. The area under the serum concentration versus time curve (AUC∞) ranged from 111 to 1,364 ng•hour/mL.
Distribution Zanamivir plasma protein binding is less than 10% and the blood to plasma ratio is 0.56. The volume of distribution is approximately 16 L. The 2 major sites of deposition are the oropharynx and the lungs (mean 77.6% and 13.2%, respectively).
Elimination The serum half‑life of zanamivir following administration by oral inhalation ranges from 2.5 to 5.1 hours. Metabolism: No metabolites have been detected in humans. Excretion: Zanamivir is eliminated by renal filtration with excretion of a single dose completed within 24 hours.
Total clearance ranges from 2.5 to
10.9L/hour. Unabsorbed drug is excreted in the feces. Specific Populations Patients with Hepatic Impairment: The pharmacokinetics of zanamivir have not been studied in patients with impaired hepatic function.
Patients with Renal Impairment: After a single intravenous dose of 4 mg or 2 mg of zanamivir in volunteers with renal impairment determined by the Cockcroft and Gault method, significant increases in systemic exposure were observed ( Table 5 ). Table 5. Zanamivir Exposure in Subjects with Renal Impairment Compared with Healthy Subjects Cmax = Maximum serum concentration; AUC0-inf = Area under the serum concentration-time curve from zero to infinity; CrCl = Creatinine Clearance. a Geometric mean (95% confidence interval).
CrCl >70 mL/min (n = 7) CrCl = 25-70 mL/min (n = 5) CrCl <25 mL/min (n = 5) C max (ng/mL) a 257 (182, 363) 316 (234, 427) 202 (141, 289) AUC 0-inf (ng∙h/mL) a 737 (567, 957) 1,519 (1181, 1954) 2,587 (1514, 4419) Pediatric Patients: The pharmacokinetics of zanamivir were evaluated in pediatric subjects with signs and symptoms of respiratory illness. Sixteen subjects, aged 6 to 12 years, received a single dose of 10 mg zanamivir dry powder via DISKHALER. Five subjects had either undetectable zanamivir serum concentrations or had low drug concentrations (8.32 to 10.38 ng/mL) that were not detectable after 1.5 hours.
Eleven subjects had C max median values of 43 ng/mL (range: 15 to 74) and AUC∞ median values of 167 ng•hour/mL (range: 58 to 279). Low or undetectable serum concentrations were related to lack of measurable PIFR in individual subjects [see Use in Specific Populations ( 8.4 ), Clinical Studies ( 14.1 )] . Geriatric Patients: The pharmacokinetics of zanamivir have not been studied in subjects older than 65 years [see Use in Specific Populations ( 8.5 )] .
Gender, Race, and Weight: There were no clinically significant pharmacokinetic changes associated with gender, race, or weight. Drug Interaction Studies Zanamivir is not a substrate of cytochrome P450 (CYP) isoenzymes or P-glycoprotein (P-gp), does not inhibit renal transporters OAT1-4, OCT1-3, or URAT1, and does not inhibit CYP isoenzymes CYP1A1/2, 2A6, 2C9, 2C19, 2D6, 2E1, and 3A4 in human liver microsomes.
12.4Microbiology Mechanism of Action Zanamivir is an inhibitor of influenza virus neuraminidase (NA), an enzyme that releases viral particles from the plasma membrane of infected cells and promotes virus spread in the respiratory tract. In neuraminidase inhibition assays, zanamivir is active against all NA enzyme subtypes N1 to N9. The median baseline 50% neuraminidase inhibitory concentrations…
🧬 Mechanism of Action ▾
12.1Mechanism of Action Zanamivir is an antiviral drug with activity against influenza virus [see Microbiology ( 12.4 )] .
📦 How Supplied / Storage and Handling ▾
16 HOW SUPPLIED/STORAGE AND HANDLING RELENZA is supplied in a circular double-foil pack (a ROTADISK) containing 4 blisters of the drug. Five ROTADISKs are packaged in a white polypropylene tube. The tube is packaged in a carton with 1 blue and gray DISKHALER inhalation device (NDC 0173-0681-01).
Store at 25 ° C (77 ° F); excursions permitted to 15 ° to 30 ° C (59 ° to 86 ° F) (see USP Controlled Room Temperature). Keep out of reach of children. Do not puncture any RELENZA ROTADISK blister until taking a dose using the DISKHALER.
📋 Description ▾
11 DESCRIPTION The active component of RELENZA is zanamivir. The chemical name of zanamivir is 5-(acetylamino)-4-[(aminoiminomethyl)-amino]-2,6-anhydro-3,4,5-trideoxy-D-glycero-D-galacto-non-2-enonic acid. It has a molecular formula of C 12 H 20 N 4 O 7 and a molecular weight of 332.3.
It has the following structural formula: Zanamivir is a white to off-white powder for oral inhalation with a solubility of approximately 18 mg/mL in water at 20°C. RELENZA is for administration to the respiratory tract by oral inhalation only. Each RELENZA ROTADISK contains 4 regularly spaced double-foil blisters with each blister containing a powder mixture of 5 mg of zanamivir and 20 mg of lactose (which contains milk proteins).
The contents of each blister are inhaled using a specially designed breath-activated plastic device for inhaling powder called the DISKHALER. After a RELENZA ROTADISK is loaded into the DISKHALER, a blister that contains medication is pierced and the zanamivir is dispersed into the air stream created when the patient inhales through the mouthpiece. The amount of drug delivered to the respiratory tract will depend on patient factors such as inspiratory flow.
Under standardized in vitro testing, RELENZA ROTADISK delivers 4 mg of zanamivir from the DISKHALER device when tested at a pressure drop of 3 kPa (corresponding to a flow rate of about 62 to 65 L/minute) for 3 seconds. zanamivir structural formula
💬 Information for Patients ▾
17 PATIENT COUNSELING INFORMATION Advise the patient to read the FDA-approved patient labeling (Patient Information and Instructions for Use). Bronchospasm Inform patients of the risk of bronchospasm, especially in the setting of underlying airways disease, and advise patients to stop RELENZA and contact their healthcare provider if they experience increased respiratory symptoms during treatment such as worsening wheezing, shortness of breath, or other signs or symptoms of bronchospasm [see Warnings and Precautions ( 5.1 )] .
If a decision is made to prescribe RELENZA for a patient with asthma or chronic obstructive pulmonary disease, the patient should be made aware of the risks and should have a fast-acting bronchodilator available. Concomitant Bronchodilator Use Patients scheduled to take inhaled bronchodilators at the same time as RELENZA should be advised to use their bronchodilators before taking RELENZA. Neuropsychiatric Events Inform patients with influenza (the flu), particularly children and adolescents, they may be at an increased risk of seizures, confusion, or abnormal behavior early in their illness.
These events may occur after beginning RELENZA or may occur when flu is not treated. These events are uncommon but may result in accidental injury to the patient. Therefore, patients should be observed for signs of unusual behavior and a healthcare professional should be contacted immediately if the patient shows any signs of unusual behavior [see Warnings and Precautions ( 5.3 )] .
Risk of Influenza Transmission to Others Inform patients that the use of RELENZA for treatment of influenza has not been shown to reduce the risk of transmission of influenza to others. Missed Dose Instruct patients that if they miss a dose of RELENZA, to take it as soon as they remember. If it is 2 hours or less before their next dose, instruct patients not to take the missed dose and to take the next dose of RELENZA at the next scheduled time.
Advise patients not to double their next dose or take more than the prescribed dose. Instructions for Use Instruct patients in use of the delivery system. Instructions should include a demonstration whenever possible.
For the proper use of RELENZA, the patient should read and follow carefully the accompanying Instructions for Use. If RELENZA is prescribed for children, it should be used only under adult supervision and instruction, and the supervising adult should first be instructed by a healthcare professional [see Dosage and Administration ( 2.1 )] . Trademarks are owned by or licensed to the GSK group of companies.
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