Antiviral therapy is recommended for patients who are at higher risk of complications from the Influenza virus. Antiviral drugs diminish symptoms, shorten the time of the disease, and prevent serious complications. The two main antiviral agents used in the treatment and prevention of influenza are Oseltamivir and Zanamivir. For the majority of patients, the treatment of influenza is primarily symptomatic and includes Analgesics, Antihistamines, Decongestants and cough suppressants.
Neurologic and neurodevelopment conditions (including disorders of the brain, spinal cord, peripheral nerve, and muscle such as cerebral palsy, epilepsy, stroke, intellectual disability [mental retardation], moderate to severe developmental delay, muscular dystrophy, or spinal cord injury)
Persons with immunosuppression, including that caused by medications or by HIV infection
Women who are pregnant or postpartum (within 2 weeks after delivery)
Persons aged younger than 19 years who are receiving long-term aspirin therapy
American Indians/Alaska Natives
Persons who are morbidly obese (BMI > 40)
Residents of nursing homes and other chronic-care facilities.
Antiviral medications with activity against influenza viruses are an important adjunct to influenza vaccine in the control of influenza.
Influenza antiviral prescription drugs can be used to treat influenza or to prevent influenza.
Four licensed prescription influenza antiviral agents are available in the United States.
Neuraminidase inhibitors
Two FDA-approved influenza antiviral medications are recommended for use in the United States during the 2013-2014 influenza season:
Oseltamivir and zanamivir are chemically related antiviral medications known as neuraminidase inhibitors that have activity against both influenza A and B viruses.
Adamantanes
Amantadine and rimantadine are antiviral drugs in a class of medications known as adamantanes.
Adamantanes are active against influenza A viruses, but not influenza B viruses.
Antiviral treatment with neuraminidase inhibitors is recommended as early as possible for any patient with confirmed or suspected influenza who has any of the follwing conditions:
Is hospitalized.
Has severe, complicated, or progressive illness.
Is at higher risk for influenza complications (detailed in the table on the right).
"median times to alleviation were 97·5 h for oseltamivir and 122·7 h for placebo groups (difference -25·2 h, 95% CI -36·2 to -16·0)" [2]
"a reduction in the time to first alleviation of symptoms from 7 to 6.3 days"[1]
The Cochrane assessment has evolved:
2000: "Eight trials with 1180 adults were included." "As a treatment, NIs shorten the duration of symptoms by one da...NIs are effective for the prevention and treatment of influenza. Overall NIs are safe..."[3]
2006: "We identified four prophylaxis, 13 treatment and four post-exposure prophylaxis (PEP) trials." "Because of their low effectiveness, NIs should not be used in routine seasonal influenza control"[4]
2012: "We included and analysed data from 25 studies (15 oseltamivir and 10 zanamivir studies). We could not use data from a further 42 studies due to insufficient information or unresolved discrepancies in their data." "We found a high risk of publication and reporting biases in the trial programme of oseltamivir."[5]
2014: "We obtained 107 clinical study reports from the European Medicines Agency (EMA), GlaxoSmithKline and Roche." "Oseltamivir and zanamivir have small, non-specific effects on reducing the time to alleviation of influenzasymptoms in adults, but not in asthmatic children."[1]
"Primary care patients with influenza-like illness treated with oseltamivir recovered one day sooner on average than those managed by usual care alone"
"The effect does not appear to be mediated by influenza virus status, as measured using PCR analysis of swabs"
Antiviral resistance to oseltamivir and zanamivir among circulating influenza viruses is currently low, but this might change.
Also, antiviral resistance can emerge during or after treatment in certain patients, such as immunosuppressed individuals.
As in recent past seasons, there is a high prevalence (>99%) of influenza A(H3N2) and influenza A(H1N1) (2009 H1N1) viruses resistant to adamantanes.
Therefore, amantadine and rimantadine are not recommended for antiviral treatment or chemoprophylaxis of currently circulating influenza A viruses.
Antiviral Medications Recommended for Treatment and Chemoprophylaxis of Influenza[edit | edit source]
Antiviral Agent
Activity Against
Use
Recommended For
Not Recommended for Use in
Adverse Reactions
Oseltamivir (Tamiflu®)
Influenza A and B
Treatment
Any age
N/A
Nausea, vomiting. Sporadic, transient neuropsychiatric events (self injury or delirium) mainly reported among Japanese adolescents and adults.
Prophylaxis
> 3 months of age
N/A
Zanamivir (Relenza®)
Influenza A and B
Treatment
> 7 years old
Patients with underlying respiratory disease, such as asthma or COPD
Allergic reactions such as oropharyngeal or facial edema. Diarrhea, nausea, sinusitis, nasal signs and symptoms, bronchitis, cough, headache, dizziness, and ear, nose and throat infections.
Prophylaxis
> 5 years old
Patients with underlying respiratory disease, such as asthma or COPD
Recommended Oseltamivir and Peramivir Dose Adjustments for Treatment or Chemoprophylaxis of Influenza in Adult Patients with Renal Impairment or End Stage Renal Disease (ESRD) on Dialysis[edit | edit source]
Antiviral Agent
Creatinine Clearance
Recommended Treatment Regimen
Recommended Chemoprophylaxis Regimen
Oral Oseltamivir
Creatinine clearance 61 to 90 mL/min
75 mg twice a day
75 mg once daily
Creatinine clearance 31 to 60 mL/min
30 mg twice a day
30 mg once daily
Creatinine clearance 10 to 30 mL/min
30 mg once daily
30 mg every other day
ESRD Patients on Hemodialysis (Creatinine clearance ≤10 mL/min)
30 mg after every hemodialysis cycle. Treatment duration not to exceed 5 days
Children and teenagers with flu symptoms (particularly fever) should avoid taking aspirin as taking aspirin in the presence of influenza infection (especially Influenzavirus B) can lead to Reye's syndrome, a rare but potentially fatal disease of the liver.[9]