Antiviral Drugs: Mechanism of Action and Adverse Effects Quiz

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Questions and Answers

Which virus is targeted by Interferon Alpha?

Hepatitis C virus (correct)

Herpes simplex virus

Human papillomavirus (HPV)

Influenza virus

What is the mechanism of action of Sofosbuvir?

Prevent viral assembly and release

Inhibit RNA polymerase (correct)

Inhibit DNA polymerase

Block viral entry into host cells

What is the spectrum of activity of Interferon Gamma?

Chronic granulomatous disease (correct)

Human papillomavirus (HPV)

Herpes zoster virus

Hepatitis C virus

Which adverse effect is commonly associated with Sofosbuvir?

Nausea Signup and view all the answers

What is the resistance mechanism seen with some antivirals?

Mutation in the drug target site Signup and view all the answers

Which condition is NOT part of the spectrum of activity of Interferon Alpha?

Relapsing remitting multiple sclerosis Signup and view all the answers

Which antiviral medication is known for inhibiting viral DNA polymerase?

Acyclovir Signup and view all the answers

What is a common adverse effect of orally administered Acyclovir?

Renal failure Signup and view all the answers

Which antiviral medication is specifically approved for the treatment of acute herpes zoster?

Famcyclovir Signup and view all the answers

What is a significant resistance mechanism to Gancyclovir?

Cytomegalovirus producing thymidine kinase through an alternate route Signup and view all the answers

Which antiviral medication is known to cause anemia and seizures as adverse effects?

Foscarnet Signup and view all the answers

What is the active form of Famcyclovir that shares the mechanism of action with Acyclovir?

Penciclovir Signup and view all the answers

What is the mechanism of action of vidarabine?

Inhibits viral DNA synthesis Signup and view all the answers

Which of the following viruses is vidarabine effective against?

Herpes simplex virus Signup and view all the answers

What is the mechanism of resistance to vidarabine?

Altered viral DNA polymerase Signup and view all the answers

What is the primary adverse effect of vidarabine?

CNS side effects and fluid overload Signup and view all the answers

What is the mechanism of action of zidovudine in the treatment of AIDS?

Inhibits viral reverse transcriptase Signup and view all the answers

What are the two mechanisms of action of interferon in the treatment of viral infections?

Directly induces enzymes that degrade viral RNA and stimulates the immune system Signup and view all the answers

Study Notes

Interferons

Interferons are naturally occurring glycoproteins that can be synthesized using recombinant DNA technology and administered IV
Interferon alpha is used to treat chronic hepatitis B/C, genital warts caused by HPV, hairy cell leukemia, and Kaposi sarcoma
Interferon beta is used to treat relapsing-remitting multiple sclerosis
Interferon gamma is used to treat chronic granulomatous disease

Adverse Effects of Interferons

Influenza-like symptoms: fever, lethargy, headache, myalgia
Bone marrow depression
Cardiovascular problems: congestive heart failure
Acute hypersensitivity reactions
Hepatic failure and pulmonary infiltrates (rare)

Sofosbuvir (Sovaldi)

Mechanism of action: inhibits RNA polymerase, incorporated into HCV RNA by NS5B polymerase, and acts as a chain terminator
Spectrum: chronic hepatitis C virus in combination with pegylated interferon and ribavirin or with ribavirin alone for 6 months
Adverse effects: fatigue, headache, nausea, rash, irritability

Antiviral Medications

Acyclovir

Mechanism of action: inhibits viral DNA polymerase
Resistance: altered or deficient thymidine kinase or DNA polymerase
Adverse effects: depend on route of administration (local irritation, nausea, vomiting, diarrhea, headache, renal failure)

Gancyclovir

Mechanism of action: same as acyclovir
Resistance: cytomegalovirus is deficient in thymidine kinase but forms the drug by another route
Adverse effects: severe and dose-dependent neutropenia, carcinogenic, teratogenic, and embryotoxic

Famcyclovir

Mechanism of action: same as acyclovir (active form is penciclovir)
Spectrum: approved only orally for the treatment of acute herpes zoster
Adverse effects: headache, nausea, mammary adenocarcinoma, and testicular toxicity

Foscarnet

Mechanism of action: reversibly inhibits DNA/RNA polymerases
Spectrum: only in cytomegalic rhinitis in HIV patients
Resistance: mutation in polymerase structure
Adverse effects: nephrotoxicity, anemia, fever, hypo K/MG/CA/PO4, seizures, and arrhythmia

Vidarabine

Mechanism of action: inhibits viral DNA synthesis
Spectrum: herpes simplex encephalitis (penetrates blood-brain barrier) and herpes simplex keratoconjunctivitis (as an ointment)
Resistance: altered DNA polymerase
Adverse effects: short-term CNS side effects and fluid overload

AIDS Treatment

Zidovudine

Mechanism of action: inhibits viral reverse transcriptase

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Description

Test your knowledge on antiviral drugs such as Acyclovir and Ganciclovir by understanding their mechanism of action, resistance mechanisms, and adverse effects based on different routes of administration. Explore how these drugs inhibit viral DNA polymerase and the implications of altered or deficient thymidine kinase or DNA polymerase.