Antiviral Drugs: Oseltamivir and Zanamivir
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Questions and Answers

What is the mechanism of action of Oseltamivir and Zanamivir?

  • Block M2 proton ion channel
  • Block viral uncoating
  • Activate the immune system
  • Selectively inhibit neuraminidase (correct)

    • What is the route of administration for Zanamivir?

  • Oral
  • Topical
  • Inhalation (correct)
  • Intravenous

    • What is the common adverse effect of Oseltamivir?

  • Headache
  • Nausea and vomiting (correct)
  • Respiratory discomfort
  • All of the above

    • What is the duration of treatment with Oseltamivir?

    <p>5-day course</p> Signup and view all the answers

    Which antiviral drugs are active against Influenza A and B viruses?

    <p>Neuraminidase inhibitors</p> Signup and view all the answers

    What is the mechanism of action of Adamantane antivirals?

    <p>Block M2 proton ion channel</p> Signup and view all the answers

    Why are Adamantane antivirals no longer recommended?

    <p>High resistance</p> Signup and view all the answers

    What is the administration route of zidovudine?

    <p>Oral and IV</p> Signup and view all the answers

    How are Oseltamivir and Zanamivir excreted?

    <p>In the urine</p> Signup and view all the answers

    What is the elimination pathway of abacavir?

    <p>Hepatic glucuronidation and carboxylation</p> Signup and view all the answers

    What is a common adverse effect of NRTIs?

    <p>Lactic acidosis with hepatic steatosis</p> Signup and view all the answers

    What is a known hypersensitivity reaction to abacavir?

    <p>Fever, fatigue, rash, GI disturbances, and respiratory distress</p> Signup and view all the answers

    What is the mechanism of resistance to NRTIs?

    <p>Alterations of viral RT</p> Signup and view all the answers

    What is a characteristic of cross-resistance between NRTIs?

    <p>Occurs between agents of the same analog class</p> Signup and view all the answers

    What is a characteristic of NRTIs?

    <p>Inhibit the reverse transcription of HIV RNA into DNA</p> Signup and view all the answers

    What is the classification of NNRTIs?

    <p>Non-nucleoside reverse transcriptase inhibitors</p> Signup and view all the answers

    What is the mechanism of action of acyclovir?

    <p>Inhibits viral DNA synthesis</p> Signup and view all the answers

    What is the bioavailability of oral acyclovir?

    <p>15-20%</p> Signup and view all the answers

    What is the primary route of excretion for acyclovir and its metabolites?

    <p>Urine</p> Signup and view all the answers

    What is the concentration of acyclovir in the cerebrospinal fluid (CSF) compared to serum values?

    <p>20-50% of serum values</p> Signup and view all the answers

    What is the most effective route of administration for treating herpes simplex encephalitis?

    <p>IV</p> Signup and view all the answers

    What is the benefit of topical acyclovir in treating recurrent genital herpes?

    <p>No benefit</p> Signup and view all the answers

    What is the characteristic of an asymptomatic intestinal infection in amebiasis?

    <p>It has no symptoms</p> Signup and view all the answers

    What is the contraindication of diloxanide furoate?

    <p>Pregnancy</p> Signup and view all the answers

    What is the main route of excretion of iodoquinol?

    <p>Feces</p> Signup and view all the answers

    What is the class of antibiotic that paromomycin sulfate belongs to?

    <p>Aminoglycoside</p> Signup and view all the answers

    What is the site of action of paromomycin sulfate?

    <p>Luminal forms of Entamoeba histolytica</p> Signup and view all the answers

    What is the main adverse effect of iodoquinol?

    <p>All of the above</p> Signup and view all the answers

    What is the mechanism of action of enfuvirtide?

    <p>Polypeptide that binds to viral gp41 required for entry into CD4 cells</p> Signup and view all the answers

    What is the route of administration of enfuvirtide?

    <p>Subcutaneous injection</p> Signup and view all the answers

    What is the mechanism of action of maraviroc?

    <p>Blocks the CCR5 coreceptor that works with viral gp41 to facilitate HIV entry</p> Signup and view all the answers

    What is a common adverse effect of maraviroc?

    <p>Hepatotoxicity</p> Signup and view all the answers

    What is the mechanism of action of integrase inhibitors?

    <p>Inhibiting the insertion of proviral DNA into the host cell genome</p> Signup and view all the answers

    What are common adverse effects of integrase inhibitors?

    <p>Nausea, diarrhea</p> Signup and view all the answers

    What is the role of ritonavir and cobicistat in HIV treatment?

    <p>Boosters of other antiviral drugs</p> Signup and view all the answers

    What is the class of antiviral drugs that enfuvirtide belongs to?

    <p>Entry inhibitors</p> Signup and view all the answers

    Study Notes

    Antiviral Drugs

    • Oseltamivir and Zanamivir:
      • No interference with vaccines
      • Active against Influenza A and B viruses
      • Administered prior to exposure or within 48 hours after onset of symptoms
      • 5-day course
      • MOA: Selectively inhibit neuraminidase, preventing the release of new virions
      • PK: Oseltamivir is a prodrug, administered orally, and activated by hepatic esterases; Zanamivir is active, administered via inhalation; both are excreted in the urine
      • Adverse effects: Oseltamivir - nausea and vomiting (minimized with food), headache; Zanamivir - respiratory discomfort; caution in patients with airway diseases
      • Resistance: Mutations of the neuraminidase enzyme

    Antiviral Drugs

    • Adamantane antivirals (e.g. Amantadine and Rimantadine):
      • Active against Influenza A viruses only
      • Administered prior to exposure or within 48 hours after onset of symptoms
      • Due to high resistance, no longer recommended
      • MOA: Block M2 proton ion channel, blocking viral uncoating
      • PK: Amantadine is excreted unchanged in the urine; Rimantadine is extensively metabolized before urinary excretion
      • Use of Amantadine in Parkinson's disease

    Antiviral Drugs

    • Acyclovir:
      • MOA: Inhibits viral DNA synthesis
      • PK: Oral, IV, and topical administration; partially metabolized to an inactive drug; drug and metabolites excreted in the urine
      • Oral acyclovir has low bioavailability (15-20%); absorption is not affected by food; no systemic concentrations are detected by the topical route
      • Diffuses readily into most tissues and body fluids (20-50% of serum values inside CSF)
      • IV: Used for herpes simplex encephalitis, neonatal HSV infections, and serious HSV or VZV infections
      • Topical: Used for cold sores, genital herpes, and ophthalmic; no benefit in treating recurrent genital herpes

    Antiviral Drugs

    • NRTIs:
      • PK: Administered orally (zidovudine available also as IV); renally excreted (except abacavir, which is hepatically eliminated)
      • Adverse effects: Toxicities due to inhibition of mitochondrial DNA polymerase gamma; lactic acidosis with hepatic steatosis, lipodystrophy
      • Abacavir: Hypersensitivity (fever, fatigue, rash, GI disturbances, respiratory distress)
      • Resistance: Alterations of viral RT; cross-resistance occurs between agents of the same analog class

    Antiviral Drugs

    • NNRTIs:
      • Boosters: Ritonavir and cobicistat

    Antiviral Drugs

    • Entry Inhibitors:
      • Enfuvirtide: Fusion inhibitor; polypeptide that binds to viral gp41 required for entry into CD4 cells; administered via SC injection; causes pain, erythema, induration, and nodules
      • Maraviroc: Entry inhibitor; blocks the CCR5 coreceptor that works with viral gp41 to facilitate HIV entry; hepatotoxic

    Antiviral Drugs

    • Integrase Inhibitors:
      • Examples: Raltegravir, elvitegravir, dolutegravir, and bictegravir
      • Inhibits the insertion of proviral DNA into the host cell genome
      • Adverse effects: Nausea, diarrhea

    Antiprotozoal Drugs

    • Amebiasis:
      • Diloxanide furoate: Not used in pregnancy; adverse effects: flatulence (common), nausea, and abdominal cramps (infrequent), rashes (rare)
      • Iodoquinol: Active against luminal cysts and trophozoites; 90% retained in the intestine; excreted in feces; remainder is absorbed, glucuronidated, and excreted in the urine
      • Adverse effects: Diarrhea, anorexia, nausea, vomiting, abdominal pain, headache, rash, and pruritus
      • Paromomycin sulfate: Aminoglycoside antibiotic; active against luminal forms of Entamoeba histolytica; not significantly absorbed; small amount absorbed is excreted unchanged in urine

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    Description

    This quiz covers the mechanisms, administration, and adverse effects of Oseltamivir and Zanamivir, antiviral drugs used to treat Influenza A and B viruses.

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