Antiviral Drugs

Question 1

Oseltamivir / Zanamivir

Answer 1

Treatment for: Influenza A & B

MOA: Neuraminidase inhibitor, prevents new visions from budding

ROA: Osel = Oral, Zana = respiratory

Elimination: Renal

Adverse: Osel = GI upset, Zana = broncospasm

Start within 48 hours
Resistance is rare

Question 2

Amatidine / rimAntadine

Answer 2

Treatment for: Influenza A ONLY!!!!

MOA: M2 proton channel blocker, prevents viral uncoating

ROA: Oral (accum in lungs)

Elimination: Amant = Renal, Rimant = Hep, Both = breast milk!!! DON’T USE IF FEEDING

Administer 1-2 days PRIOR and 6-7 days during

ADR: GI upset, insomnia, confusion, headache (dec CNS effect w/ rimant)

• Both are teratogenic in animals. Category C for use during pregnancy, but generally not recommended

COMMON RESISTANCE!!

Question 3

Cyclovirs

Answer 3

MOA: Nucleoside analog specifically for viral kinase –> HIGHEST SELECTIVE TOXICITY!!

Treatment for:

• Oral: shorten Herpes outbreak, topical sucks
• IV: serious HSV & VZV ONLY

ROA:

• Acyclovir: IV or topical (poor oral)
• Valacyclovir: Oral
• Famciclovir: Oral
• Penciclovir: Topical

Elimination: RENAL

Adverse: headache, n/v. Higher w/ Val causing reversible renal dysfunction. IV = encephalopathy (CNS)

Question 4

Docosanol

Answer 4

Prevents viral fusion

Topical treatment within 12h for HSV

Question 5

GanCIClovir / valganCIClovir

Answer 5

MOA: Nucleotide analog, DNA Pol inhibitor (same as cyclovirs)

Treatment for: HSV (Gan) and CMV (Val)

ROA: IV, IO, sorta PO (Gan) and Oral (Val)

Excretion: Renal

ADR: MYELOSUPPRESSION, nausea, diarrhea, fever, rash, HA, insomnia

Question 6

Cidofivir

Answer 6

MOA: DNA polymerase inhibitor, nucleoTTTide (cytosine monophosphate) analog, phosphorylated by HOST KINASE!!! (less selective)

Treatment for: CMV

ROA: IV (weekly/biweekly)

ADR: NEPHROTOXICITY, rash in HIV pts

Question 7

Foscarnet

Answer 7

MOA: inorganic pyrophosphate that binds noncompetitively to DNA/RNA polymerases (also RT) and inactivates them

Treatment for: CMV

ROA: IV (req continuous infusion)

Excretion: Renal

Adverse: renal impairment, severe n/v, electrolyte imbalance, hypocalcemia

Question 8

Describe the sites of antiviral drug action in relation to the replicative life cycle of the respective virus

Answer 8

Viral attachment and entry/penetration
Uncoating
Nucleic acid synthesis
Protein synthesis
Viral release (budding)

Question 9

Relate the mechanism of action to selective toxicity and development of resistance

Answer 9

Best selective toxicity with analogs (e.g., acyclovir) that are activated by VIRAL kinases rather than host cell kinases (e.g., ganciclovir). However, these viruses can develop resistances easily since the target is so specific

Acyclovir = Ganciclovir > Cidofivir > Foscarnet

Question 10

Describe the clinical relevance of nucleoside and nucleotide analogs being prodrugs that require intracellular activation and intracellular vs plasma half-life of active drug

Answer 10

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