anti influenza drugs

1. ANTI INFLUENZA DRUGS

2. INFLUENZA
 Influenza is caused by RNA viruses of the
family Orthomyxoviridae.
 Species of origin (e.g. avian i.e. bird or swine
i.e. pigs )
 Influenza viruses makeup of 3 genera of
orthomyxoviridae family:
 Influenza A
 Influenza B
 Influenza C

3. INFLUENZA VIRUS

4. INFLUENZA A
 Is the only strain that causes pandemics.
 Is classified into 16 H (hemagglutinin) and 9 N
(neuraminidase) known subtypes based on
surface glycoprotein's.
 Can infect a variety of animal hosts.
 Rapidly mutate within poultry
 Have recently expanded their host range to
cause both avian and human disease.

5. Influenza B:
• Most exclusively infect humans
• Mutate at 2-3 times slower rate than Influenza A
• Less common then influenza A

7. ANTI INFLUENZA DRUGS
 M2 Ion channel Inhibitors
- Amantadine
- Rimantidine
 Neuraminidase Inhibitor
-Oseltamivir
-Zanamivir

8. AMANTADINE
 It inhibits M2 proton channel present on virus
surface.
 As acidification of interior of endosome is required
for dissociation of viral assembly and then onset of
viral replication
 This drug targets M2 proton channel hence
inhibiting it and thus inhibiting the viral uncoating in
host cell.
 Activity: Influenza A only
 Resistance: Develops by mutation causing amino
acid substitution in M2 protein leading to inability of
amantadine to bind to M2 proton channel.

9.  Administration: oral
 Adverse effects:
- nausea, anorexia, insomnia, dizziness,
nightmares, lack of mental concentration etc.
Increase in the resistance of drug in clinical
isolates over the last decade, in influenza A
H1N1 as well as H3N2, has limited the
usefulness of this agent for either the treatment
or the prevention of influenza.

10. RIMANTADINE
 Mechanism of action: similar to amantadine.
 More potent, long acting and better tolerated
than amantadine.
 Activity : Influenza A only
 Amantadine resistance virus is resistant to
rimantadine as well.

11. OSELTAMIVIR (TAMIFLU)
 Neuraminidase inhibitor
 Prodrug that is activated by hepatic esterases
(active form- osteltamivir carboxylate)
 Interfere with release of influenza virus from
infected to new host cells.
 Competitively and reversibly interact with the active
enzyme site to inhibit neuraminidase activity.
 Administration: oral

12.  Activity: Influenza A and Influenza B both
 Adverse effects: nausea, abdominal pain due to
gastric irritation, headache, diarrhoea, cough
and insomnia.

13. ZANAMIVIR (RELENZA)
 Mechanism of action is similar to oseltamivir.
 Mode of administration : Inhalation as oral
bioavailability is very low
 Activity : Influenza A and influenza B both
 Adverse Effects: cough, bronchospasm,
headache, dizziness, nausea etc.