Neuraminidase Inhibitors

Question 1

Neuraminidase Inhibitors

Answer 1

Oseltamivir
Peramivir
Zanamivir

Active against influenza A and B
Amantadine and Rimantidine active only against A

Prevent the viral neuraminidase enzyme from releasing new virions from the host cell which prevents further replication

Drugs differ in form of delivery
Osel- oral pro drug
Pera- IV
Zan- inhaled 
Can be used as treatment or prophylaxis in those not able to get the vaccine

Question 2

Neuraminidase Inhibitors MOA

Answer 2

Competitive inhibitors of viral neuraminidase, an enzyme responsible for several functions of the influenza virus including the release of new virions from infected cells

Question 3

Neuraminidase Inhibitors Spectrum

Answer 3

Good
Influenza A and B

Poor
Other viruses

Question 4

Neuraminidase Inhibitors Adverse Effects

Answer 4

Generally well tolerated

Osel can cause N/V, abdominal pain; tend to be transient effects
Headache and fatigue (particularly during prophylaxis when drug given for longer period of time)

Zan- mostly pulmonary (cough and bronchospasm)
Avoid use in asthma or other reactive pulmonary diseases

Per- limited experience; no characteristic adverse effects

Question 5

Neuraminidase Inhibitors Important Facts

Answer 5

Most effective when started early in infection because viral replication peaks early (48-72 hours after infection)
Start in patients who have been symptomatic for no more than 2 days (based on indication for mild-mod disease in healthy adults
In severe disease (hospitalization or vulnerable patients) data suggests may be beneficial if started outside this window

Resistance can occur
Utility dictated by degree of resistance that exists in the dominant strains of the season
Zan active against majority of strains resistant to the other two but patterns may change

Osel and Zan are highly effective at prophylaxis when predominant strains in the community are susceptible; not a substitute for the vaccine
Adverse effects more common with the longer duration prophylaxis than shorter duration treatment

All 3 effective at treating and preventing influenza if circulating strains are susceptible
Vast majority of data is with uncomplicated patients
Desired route of administration decided what drug to use