RELENZA's Mechanism of Action
Inhibition of both influenza A and B viruses
The mechanism of action of RELENZA is via inhibition of influenza virus neuraminidase with the possibility of alteration of virus particle aggregation and release. [1]
RELENZA inhibits both influenza A and B virus neuraminidases, which are viral enzymes that are essential for the release of virus from infected cells. [11] By possibly interfering with the release of progeny influenza virus from infected host cells, RELENZA may prevent infection of new host cells and halt the spread of infection in the respiratory tract. [12]
Panel A shows the action of neuraminidase in the continued replication of virions in influenza infection. The replication is blocked by neuraminidase inhibitors (Panel B), which prevent virions from being released from the surface of infected cells.
Reproduced from Moscona A. N Engl J Med. 2005:353:1363-1373, with permission.
Administration timeframe relates to mechanism of action
RELENZA acts at the stage of viral replication of influenza. Because the replication of influenza virus in the respiratory tract reaches its peak between 24 and 72 hours after the onset of illness [12], it is recommended that RELENZA be administered as early as possible and no later than 48 hours after symptoms develop.
Drug delivery to the primary site of viral replication
RELENZA is for administration to the respiratory tract—the primary site of viral replication—by oral inhalation via the DISKHALER Inhalation Device. [10]
next:
DISKHALER Delivery System
Important Safety Information
RELENZA IS NOT RECOMMENDED FOR TREATMENT OR PROPHYLAXIS OF INFLUENZA IN INDIVIDUALS WITH UNDERLYING AIRWAY 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 airway 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
- RELENZA has not been proven effective for treatment of influenza in individuals with underlying airways disease.
- Patients should be instructed in the use of the delivery system. Instructions should include a demonstration whenever possible
- If treatment with RELENZA is considered for a patient with underlying airway 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
- Common adverse events in treatment and prophylaxis studies with RELENZA were nausea, diarrhea, sinusitis, viral respiratory infections, headaches, nasal signs and symptoms. The incidence of these adverse events was similar in both groups for RELENZA and placebo-treated groups
Click here for Complete Prescribing Information for RELENZA.
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