influenza viruses

Question 1

Antiviral agents used to treat influenza viruses :

Answer 1

Amantadine

Oseltamivir + Zanamivir (Neuraminidase inhibitors)

Question 2

Therapeutic uses of Amantadine:

Answer 2

1) to prevent and treat influenza type A (not B)
(Given with 480h >decrease viral symptoms 2days)

2) to treat Parkinson’s disease (reduce tremor & dyskinesia in 70%, its effectiveness fades)

Question 3

M.o.a of amantadine:

Answer 3

1) Block influenza A M1 ion channel protein
2) reduce influx of protons
3) inhibit viral capsule disassembly (inhibit uncoating)

Question 4

Pharmacokinetic of Amantadine:

Answer 4

orally available

well absorbed from the GI tract

Eliminated by kidney (dose must be reduced in renal insufficiency)

Question 5

Adverse effects of Amantadine:

Answer 5

Tremor
Nervousness
Confusion
Dizziness
Peripheral edema (ankle edema)
Livdo reticularis * unique

Question 6

Therapeutic uses of Neuraminidase Inhibitors (Oseltamivir & Zanamivir):

Answer 6

1) prevention and treatment of influenza A & B

Within 2 days

Question 7

Pharmacokinetic of Oseltamivir:

Answer 7

Well absorbed from GIT (bioavailability > 0.8)

prodrug & hydrolyzed by the liver enzymes to its active metabolite

Question 8

Pharmacokinetics of Zanamivir:

Answer 8

1) Extremely poor absorption form GIT

2) Available as a dry powder for oral inhalation

Question 9

Side effects of Neuraminidase Inhibitors:

Answer 9

❖ Well-tolerated (nausea/vomiting and headache)
❖ Bronchospasm
❖ They have less CNS adverse effects compared to amantadine

Question 10

M.o.a of Neuraminidase Inhibitors (oseltamivir + zanamivir):

Answer 10

Competitive inhibitor of neuraminidase enzyme > prevent the cleavage of sialic acid residues on the surface of the infected host cell and thus prevents the release of the progeny visions from infected cells.