Antiviral Pharmacology Overview

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Questions and Answers

What is the bioavailability percentage of the substance discussed?

5-10%

30-35%

20-25%

15-20% (correct)

Which process is primarily responsible for clearing this substance from the body?

Hepatic metabolism

Glomerular filtration and tubular secretion (correct)

Active transport in the liver

Bile excretion

What proportion of serum concentrations is found in the cerebrospinal fluid for this substance?

25%

30%

75%

50% (correct)

If the bioavailability of a drug is low, what does this indicate?

It has high first-pass metabolism Signup and view all the answers

Which of the following statements about the substance's clearance method is incorrect?

It is cleared entirely through hepatic pathways. Signup and view all the answers

What is a primary use of Nevirapine in treatment protocols?

Used in combination with at least two other antiretrovirals Signup and view all the answers

What is a common side effect associated with Nevirapine use?

Rash Signup and view all the answers

How is Nevirapine primarily metabolized in the body?

Hepatic metabolism Signup and view all the answers

Which statement about Nevirapine's pharmacokinetics is true?

It penetrates the CSF Signup and view all the answers

Which adverse effects should be monitored in patients taking Nevirapine?

Rash and hepatitis Signup and view all the answers

Which of the following stages is NOT part of the viral replication process targeted by antiviral drugs?

Synthesis Signup and view all the answers

Which of the following antiviral agents is NOT used to treat herpes simplex viruses (HSV) and Varicella-Zoster Virus (VZV) infections?

Oseltamivir Signup and view all the answers

What is a common method of administration for Acyclovir?

Intravenous Signup and view all the answers

What is the role of antiviral drugs in relation to the host's immune system?

They modulate the host-immune system. Signup and view all the answers

Which of the following components is the first step in the viral replication process?

Adsorption Signup and view all the answers

What are common adverse reactions associated with Ganciclovir?

Neutropenia and thrombocytopenia Signup and view all the answers

Which of the following symptoms might indicate an adverse reaction to Ganciclovir?

Confusion and seizures Signup and view all the answers

What should be considered when using Ganciclovir with other medications?

Avoiding potential marrow-depressant drugs Signup and view all the answers

Which of the following is NOT a commonly reported adverse reaction of Ganciclovir?

Diarrhea Signup and view all the answers

Which condition among the following is a recognized adverse effect of Ganciclovir?

Thrombocytopenia Signup and view all the answers

What is the primary function of protease inhibitors in HIV treatment?

They disrupt the process by which proteins are cleaved into components. Signup and view all the answers

Which of the following is NOT a protease inhibitor?

Zidovudine Signup and view all the answers

What role does the HIV protease play in the virus's life cycle?

It cleaves proteins to facilitate the assembly of viral particles. Signup and view all the answers

How do protease inhibitors affect the level of HIV in the body?

They decrease the viral load by inhibiting viral protein processing. Signup and view all the answers

Which of the following statements about protease inhibitors is false?

They work by promoting the maturation of virus particles. Signup and view all the answers

What is the primary mechanism by which interferons inhibit viral replication in non-infected cells?

By stimulating the production of enzymes that degrade viral RNA Signup and view all the answers

How do interferons enhance the immune response against viruses?

By promoting the activity of immune cells against viruses Signup and view all the answers

Which type of interferon is commonly used to treat viral hepatitis B and C?

Alfa-2α and -2b Signup and view all the answers

What is a known use of Alfa interferon beyond viral infections?

Treatment for hairy cell leukemia Signup and view all the answers

Which of the following is NOT a function of interferons in combating viral infections?

Directly preventing dental cavities Signup and view all the answers

What is a common characteristic of viral hepatitis B and C that interferons target?

They lead to inflammation of the liver Signup and view all the answers

What role do interferons play in the immune response against viral infections?

They enhance the body’s ability to fight off viral infections Signup and view all the answers

Which of the following conditions can be treated with interferons?

Chronic viral infections like hepatitis Signup and view all the answers

Study Notes

Antiviral Agents

Antiviral drugs directly impair viral replication, impacting several stages, including adsorption, penetration, uncoating, biosynthesis, and release.
They also modulate the host immune system.

Herpes Simplex Virus (HSV) and Varicella-Zoster Virus (VZV) Infections

Nucleoside analogs (acyclovir, penciclovir, ganciclovir, trifluridine, cidofovir, foscarnet) are used.
These drugs inhibit viral DNA synthesis by competing with viral DNA polymerase.
Acyclovir, valacyclovir, and famciclovir are effective against HSV and VZV infections.

Acyclovir Pharmacokinetics

Acyclovir is administered orally, intravenously, and topically.
Bioavailability is 15-20%.
It is mainly cleared through glomerular filtration and tubular secretion.
Cerebrospinal fluid concentrations are approximately 50% of serum levels.

Acyclovir Adverse Reactions

Common adverse effects include stinging sensation, superficial punctate keratopathy, and gastrointestinal symptoms (e.g., headache).
Severe local inflammation can occur with intravenous administration.
Neuropsychiatric reactions are also possible.

Ganciclovir

Used to treat cytomegalovirus (CMV) infections.
Administered orally or intravenously.
It's eliminated primarily unchanged in the urine.
Bioavailability is poor.

Ganciclovir Adverse Reactions

Common side effects include neutropenia, thrombocytopenia, fever, rash, gastrointestinal problems, confusion, and seizures.
Potential marrow-depressant drugs (e.g., cotrimoxazole, zidovudine) should be avoided concurrently.

Antiretroviral Agents

Nucleoside reverse transcriptase inhibitors (NRTIs)
Non-nucleoside reverse transcriptase inhibitors (NNRTIs)
Protease inhibitors (PIs)

Zidovudine (NRTI)

Well absorbed and distributed to most body tissues and fluids.
Eliminated mainly by renal excretion following glucuronidation in the liver.

Zidovudine Drug Interactions

Myelosuppressive drugs (e.g., ganciclovir, ribavirin) and cytotoxic agents can increase toxicity.
Probenecid increases zidovudine levels by decreasing its clearance.

Nevirapine (NNRTI)

Used in combination with at least two other antiretroviral agents.
Penetrates the central nervous system (CSF).
Hepatic metabolism is significant.
Common side effects include rashes and hepatitis.

Protease Inhibitors (Ritonavir, Indinavir, Saquinavir)

Disrupt the HIV protease activity critical for virus particle assembly.
Common adverse effects include diarrhea, paresthesia, nausea, vomiting, hyperglycemia, hypertriglyceridemia, and hypercholesterolemia.

Drug Interactions with Protease Inhibitors

Enzyme inducers (e.g., rifampicin) and inhibitors (e.g., ketoconazole, cimetidine) can affect protease inhibitor metabolism.

Amantadine

Active against influenza A virus.
Interferes with viral uncoating and release.
Well absorbed from the gastrointestinal tract and excreted in the urine.
Potential adverse effects include dizziness, insomnia, nervousness, drowsiness, hallucinations, coma, and seizures, especially in patients with impaired renal function, such as those with epilepsy.

Interferons

Act directly on uninfected cells to induce enzymes degrading viral RNA.
Indirectly stimulate the immune system.
Used in hairy cell leukemia, recurrent/metastatic renal cell carcinoma, Kaposi's sarcoma, and viral hepatitis (B and C).
Common side effects include influenza-like symptoms, fatigue, anorexia, convulsions, depression, hypotension, hypertension, heart arrhythmias, and bone marrow suppression.

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Description

Test your knowledge on the pharmacokinetics and pharmacodynamics of Nevirapine and other antiviral agents. This quiz covers bioavailability, metabolism, clearance methods, common side effects, and more. Perfect for students and professionals in pharmacology and toxicology.