What is the management of Influenza B (Flu B)?

From the Guidelines

Management of influenza B involves both antiviral medications and supportive care, with neuraminidase inhibitors like oseltamivir being the first-line treatment, as recommended by the most recent guidelines 1.

Key Considerations

• Treatment should ideally begin within 48 hours of symptom onset for maximum effectiveness.
• Oseltamivir is typically prescribed at 75mg twice daily for 5 days for adults, with pediatric dosing based on weight.
• Baloxavir marboxil is an alternative, given as a single dose based on weight (40mg for patients 40-80kg, 80mg for those >80kg).
• Supportive care includes rest, adequate hydration, and fever control with acetaminophen or ibuprofen.

High-Risk Patients

• High-risk patients (elderly, pregnant women, young children, immunocompromised individuals, and those with chronic medical conditions) should be monitored closely for complications like pneumonia or respiratory distress.
• Preventive measures include annual influenza vaccination and infection control practices.

Mechanism of Action

• Neuraminidase inhibitors work by preventing viral release from infected cells, while baloxavir inhibits viral replication by blocking the cap-dependent endonuclease activity, both effectively reducing viral load and symptom duration.

Additional Considerations

• The choice of antiviral medication may depend on the specific strain of influenza and its susceptibility pattern, as well as the patient's individual characteristics and medical history 1.
• Continuous monitoring of the epidemiology, change in severity, and resistance patterns of influenza strains may lead to new guidance and updates in treatment recommendations 1.

From the FDA Drug Label

1 INDICATIONS AND USAGE

1.1 Treatment of Influenza Oseltamivir phosphate for oral suspension is 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.

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.

For flu management, the following options are available:

• Oseltamivir (PO): 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 2.
• Zanamivir (INH): indicated for the 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 3. Key considerations:
• Oseltamivir is not recommended for patients with end-stage renal disease not undergoing dialysis.
• Zanamivir is not recommended for individuals with underlying airways disease.

From the Research

Flu Management

• The management of flu involves the use of antiviral drugs, such as oseltamivir and zanamivir, which are neuraminidase inhibitors 4, 5.
• Oseltamivir has been shown to reduce the duration of symptomatic illness and hasten the return to normal levels of activity when initiated promptly in patients with naturally acquired influenza 4.
• Zanamivir and oseltamivir have been approved by the US Food and Drug Administration for the treatment of influenza A and B, and have been shown to decrease the median duration of influenza-related symptoms by approximately 1 day if initiated within 48 hours of the onset of symptoms 5.
• Oseltamivir has also been shown to be effective in the treatment of children with influenza, and in the prevention of influenza in high-risk populations such as the elderly or those with chronic cardiac or respiratory disease 4.

Treatment Efficacy

• Clinical studies have shown that neuraminidase inhibitors can decrease the median duration of influenza-related symptoms by approximately 1 day if initiated within 48 hours of the onset of symptoms of influenza 5.
• Oseltamivir has been shown to reduce the duration of viral shedding and the severity of illness in patients with influenza 4, 6.
• Zanamivir and oseltamivir have been shown to be effective in reducing the incidence of secondary complications and the use of antibacterials in patients with influenza 4, 5.

Prevention

• Oseltamivir has been shown to be effective in the prevention of influenza in healthy adults and in high-risk populations such as the elderly or those with chronic cardiac or respiratory disease 4, 7.
• Zanamivir and oseltamivir have been shown to be effective in reducing the incidence of laboratory-confirmed influenza in patients who receive the drug for prophylaxis 5, 7.
• The use of neuraminidase inhibitors for prevention has been shown to be most effective when initiated within 48 hours of symptom onset in the infected person 4, 5.

Safety and Tolerability

• Oseltamivir has been shown to be well tolerated in clinical trials, with nausea and vomiting being the most commonly reported adverse events 4, 7.
• Zanamivir has been shown to be well tolerated, but patients with asthma or chronic obstructive pulmonary disease may experience an increased incidence of adverse effects such as a decline in forced expiratory volume in one second or peak expiratory flow rates 5, 7.
• The most common gastrointestinal adverse effects of oseltamivir, such as nausea and vomiting, can be reduced by administering the medication with food 4, 7.