Čo je Relenza (Zanamivir)?
Relenza (zanamivir) is an inhaled antiviral medicine approved by the European Medicines Agency (EMA) for the treatment and prevention of influenza A and B. It belongs to the neuraminidase inhibitor class of antiviral drugs — the same class as Tamiflu (oseltamivir), though it is delivered by inhalation rather than orally.
Relenza is delivered directly to the respiratory tract — the primary site of influenza infection — via a breath-activated inhaler device called the Diskhaler. This targeted delivery means that systemic absorption is low (approximately 10–20% of the inhaled dose reaches the bloodstream), which reduces the likelihood of systemic side effects but also means Relenza is not suitable for patients who cannot inhale effectively.
Ako funguje Relenza (Zanamivir)?
Influenza viruses are coated with two surface proteins: haemagglutinin (H) and neuraminidase (N). Haemagglutinin allows the virus to attach to and enter host cells. Neuraminidase allows newly formed virus particles to detach from infected cells and spread to infect additional cells throughout the respiratory tract.
Zanamivir is a neuraminidase inhibitor: it binds directly and selectively to the neuraminidase enzyme on the surface of influenza A and B viruses, blocking its activity. By blocking neuraminidase, zanamivir:
- Prevents newly formed viral particles from detaching from infected cells
- Limits the spread of the virus to additional respiratory cells
- Reduces the total viral load in the respiratory tract
This mechanism is most effective when started early — ideally within the first 24 hours, and no later than 48 hours after symptoms begin — because viral replication is most active in this early phase.
Pre koho je určený/á Relenza (Zanamivir)?
Relenza is indicated for:
Treatment:
- Adults and children aged 5 years and over with symptomatic influenza A or B, when symptoms began within the past 48 hours
- Patients in groups at higher risk of complications (elderly, immunocompromised, those with chronic medical conditions), where antiviral treatment is particularly warranted
Prevention (post-exposure prophylaxis):
- Adults and adolescents (aged 12 and over) who have been exposed to influenza and require preventive treatment in certain circumstances, such as during outbreaks
Relenza is generally NOT recommended for:
- Patients with asthma or COPD (significant risk of bronchospasm)
- Patients who cannot use inhaler devices correctly
- Patients under 5 years of age
- People who have not started treatment within 48 hours of symptom onset (limited benefit)
Dávkovanie
Relenza is inhaled using the Diskhaler device. Each blister of the Diskhaler contains 5 mg of zanamivir powder.
| Indication | Dose | Frequency | Duration |
|---|---|---|---|
| Treatment (adults and children ≥5 years) | 10 mg (2 inhalations of 5 mg) | Twice daily | 5 days |
| Prevention (post-exposure) | 10 mg (2 inhalations of 5 mg) | Once daily | 10 days |
| Prevention (seasonal / outbreak) | 10 mg (2 inhalations of 5 mg) | Once daily | Up to 28 days |
The two inhalations for each dose should be taken one after the other. Patients with asthma or COPD who are prescribed Relenza despite the risk (in exceptional circumstances) should have a fast-acting bronchodilator available to use before each Relenza dose.
Vedľajšie účinky
Common side effects
- Bronchospasm: The most clinically important risk — sudden tightening of the airways. Particularly dangerous in patients with underlying respiratory disease.
- Headache
- Dizziness
- Throat or nasal irritation
- Nausea
Serious risks
- Severe bronchospasm: Some cases have been fatal, particularly in patients with known asthma or COPD. Relenza should be discontinued immediately if bronchospasm occurs and appropriate medical care sought.
- Neuropsychiatric events: Confusion, abnormal behaviour, delirium, and hallucinations have been reported in some patients receiving neuraminidase inhibitors, particularly children. Whether these are caused by zanamivir or are a manifestation of influenza itself is unclear.
- Anaphylaxis and allergic reactions: Rare but reported; discontinue immediately if severe hypersensitivity occurs.
Relenza vs Tamiflu
| Feature | Relenza (Zanamivir) | Tamiflu (Oseltamivir) |
|---|---|---|
| Active ingredient | Zanamivir | Oseltamivir |
| Route | Inhaled (Diskhaler) | Oral (capsule or suspension) |
| Systemic absorption | Low (~10–20%) | High (~80%) |
| Suitable for asthma/COPD | Not recommended | Preferred in respiratory disease |
| Starting age (treatment) | 5 years and over | 1 year and over |
| Side effect profile | Bronchospasm risk | Mainly GI (nausea, vomiting) |
Tamiflu is generally preferred in patients with underlying respiratory disease or those who cannot use inhaler devices. Relenza may be preferred in patients who tolerate it and for whom systemic exposure should be minimised.
Ako získať Relenza (Zanamivir) online v Európe
Relenza is a prescription-only medicine in most EU member states. Prescrivia operates as a technology intermediary, connecting patients with independent EU-registered doctors for online health assessments. We do not prescribe medicines, employ doctors, or sell medicines directly.
Note on timing: Given that antiviral treatment for influenza must be started within 48 hours of symptom onset to be effective, prompt medical consultation is critical. If you are experiencing flu symptoms, seek medical assessment as soon as possible.
Important: Prescrivia does not guarantee that a prescription will be issued. All clinical decisions are made independently by qualified medical professionals.
Dôležité bezpečnostné informácie
Nepoužívajte Relenza (Zanamivir) ak:
- Have asthma or chronic obstructive pulmonary disease (COPD)
- Cannot use inhaler devices effectively
- Are allergic to zanamivir or any excipient in Relenza
Stop Relenza and seek immediate medical attention if you:
- Experience difficulty breathing, wheezing, or chest tightness after inhalation (bronchospasm)
- Develop severe allergic symptoms
Vaccinate: Annual influenza vaccination remains the most important preventive measure against influenza and its complications, per WHO recommendations.
Zdroje
Lekárske informácie na tejto stránke vychádzajú z nasledujúcich zdrojov:
- European Medicines Agency (EMA). Relenza (zanamivir) — Summary of Product Characteristics. ema.europa.eu
- World Health Organization (WHO). Influenza (Seasonal) — Fact sheet. who.int
- World Health Organization (WHO). WHO guidelines for pharmacological management of pandemic and seasonal influenza. 2010. who.int
Tento obsah je pravidelne prehodnocovaný s ohľadom na aktualizované klinické usmernenia. Je poskytovaný len na informačné účely a nepredstavuje lekárske poradenstvo. Vždy sa poraďte s kvalifikovaným zdravotníckym pracovníkom o rade týkajúcej sa Vašich individuálnych zdravotných okolností.
Frequently asked questions
- Na čo sa používa Relenza (Zanamivir)?
- Relenza (zanamivir) is an inhaled antiviral medicine used to treat influenza A and B in adults and children aged 5 years and over when they are showing flu symptoms. It is also used to prevent influenza in adults and adolescents in certain circumstances. Relenza must be started within 48 hours of the first appearance of flu symptoms to be effective.
- Why must Relenza be started within 48 hours?
- Influenza viruses replicate most rapidly in the first 24–48 hours of infection. Zanamivir works by blocking neuraminidase — an enzyme the virus uses to release copies of itself from infected cells and spread to new cells. Starting treatment early, when viral replication is still active, significantly limits the extent of infection and shortens the duration of illness. Starting after 48 hours has passed provides little clinical benefit.
- Aký je rozdiel Relenza taken?
- Relenza is inhaled using a breath-activated inhaler device called a Diskhaler. Each dose consists of two inhalations (2 x 5 mg = 10 mg per dose), taken twice daily for 5 days. The Diskhaler contains a blister pack of powdered zanamivir and requires the patient to breathe in through the device to deliver the medication to the airways.
- Can people with asthma or COPD use Relenza?
- Caution is required. Relenza is inhaled as a powder, and has been associated with bronchospasm (sudden narrowing of the airways) in patients with underlying respiratory conditions such as asthma or COPD. Some patients have experienced severe and even fatal bronchospasm shortly after inhaling zanamivir. Relenza should generally not be used in patients with asthma or COPD; Tamiflu (oseltamivir) oral capsules are typically preferred in this group.
- Is Relenza the same as Tamiflu?
- Both Relenza (zanamivir) and Tamiflu (oseltamivir) are neuraminidase inhibitor antivirals used to treat influenza, and they have a similar mechanism of action. The key differences are the route of administration (Relenza is inhaled; Tamiflu is taken orally), their side effect profiles, and their suitability for patients with respiratory conditions. A doctor can advise which is most appropriate for individual patients.
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