Antiretroviral Therapy Quiz

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Questions and Answers

What is the role of reverse transcriptase in the synthesis of the provirus?

It helps in the entry of the virus into host cells.

It catalyzes the synthesis of viral proteins.

It integrates the provirus into the host DNA.

It synthesizes a double-stranded DNA copy from viral RNA. (correct)

Which class of antiretroviral agents is the oldest?

Nucleoside/nucleotide reverse transcriptase inhibitors (correct)

Integrase inhibitors

Protease inhibitors

Nonnucleoside reverse transcriptase inhibitors

Which combination is commonly used as a backbone for anti-HIV regimens?

Tenofovir disoproxil fumarate and Lamivudine (correct)

Stavudine and Tenofovir alafenamide

Abacavir and Didanosine

Zidovudine and Emtricitabine

What mechanism of action do NRTIs utilize to inhibit viral replication?

They replace nucleotides in viral DNA, leading to termination. Signup and view all the answers

Which of the following is NOT a nucleoside reverse transcriptase inhibitor?

Dolutegravir Signup and view all the answers

Which regimen is recommended for most treatment-naïve patients?

Two NRTIs plus an integrase inhibitor Signup and view all the answers

In the context of renal dysfunction, what must be considered for most NRTIs?

Their dosages require adjustment. Signup and view all the answers

What is the primary function of integrase inhibitors in antiretroviral therapy?

To prevent integration of provirus into host DNA. Signup and view all the answers

What is the primary mechanism of action for non-nucleoside reverse transcriptase inhibitors (NNRTIs)?

They bind to a different part of reverse transcriptase. Signup and view all the answers

Which of the following is a common adverse effect associated with efavirenz?

Rash and hepatotoxicity Signup and view all the answers

What distinguishes rilpivirine from efavirenz and nevirapine in terms of lipid profile effects?

It has less effect on lipid profiles. Signup and view all the answers

Why is strict adherence to NNRTI-based regimens crucial?

To prevent high-level resistance due to low genetic barrier. Signup and view all the answers

Which of the following statements about nevirapine is true?

It acts as an inducer of drug metabolism. Signup and view all the answers

What is a notable challenge with the use of NNRTIs in treatment regimens?

Low genetic barrier to resistance is a concern. Signup and view all the answers

Which combination is recommended for treatment-naïve patients with HIV?

rilpivirine and tenofovir/emtricitabine. Signup and view all the answers

What is the significance of the broad drug interaction profile of NNRTIs?

They create a risk for potential drug-drug interactions. Signup and view all the answers

What is a common characteristic of viruses?

They are obligate intracellular parasites. Signup and view all the answers

Which of the following best describes the function of anti-viral agents?

To block viral entry into or exit from the host cell. Signup and view all the answers

What is the main concern when using non-selective inhibitors of virus replication?

They may cause interference with the host cell's function. Signup and view all the answers

Which drug is commonly used in the treatment of Herpes Simplex Virus (HSV)?

Acyclovir Signup and view all the answers

Which step is NOT part of the viral replication process?

Absorption of nutrients from the host Signup and view all the answers

What is the key component of the virus's outer layer?

Envelope Signup and view all the answers

Which therapeutic strategy is typically used for prolonged viral infections such as HCV?

Dual therapy Signup and view all the answers

What is the purpose of the capsid in a virus?

To protect the viral nucleic acid. Signup and view all the answers

What is the primary mechanism of action for Adefovir Dipivoxil in treating HBV infection?

Competitive inhibition of HBV DNA polymerase Signup and view all the answers

Which of the following classes of direct-acting antiviral agents is NOT a target for treating hepatitis C?

HIV reverse transcriptase inhibitors Signup and view all the answers

What is the primary goal of antiviral drugs in treating hepatitis C?

Eliminate the hepatitis virus from the body Signup and view all the answers

In the case study, what is the most appropriate treatment for CMV retinitis in the presented patient?

Ganciclovir Signup and view all the answers

Which of the following is NOT considered a mainstay of chronic hepatitis C treatment?

Sofosbuvir Signup and view all the answers

Which of the following protease inhibitors can be used unboosted?

Atazanavir Signup and view all the answers

What is the primary purpose of using boosting agents like ritonavir or cobicistat with protease inhibitors?

To increase serum concentrations and half-lives of other PIs Signup and view all the answers

Which of the following combinations is a boosting combination of a protease inhibitor?

Darunavir/cobicistat Signup and view all the answers

Which mechanism of action is primarily associated with protease inhibitors in the treatment of HIV?

Cleavage of polyproteins to produce mature viral proteins Signup and view all the answers

Which entry and fusion inhibitor targets the CCR5 receptor to prevent HIV from entering cells?

Maraviroc Signup and view all the answers

What type of adverse effects are particularly associated with protease inhibitors?

Cardiovascular effects Signup and view all the answers

What should be performed before initiating treatment with maraviroc?

Tropism testing Signup and view all the answers

Which of the following statements is incorrect about protease inhibitors?

They are active against both HIV and HCV. Signup and view all the answers

What is the primary mechanism of action of Enfuvirtide?

Prevents conformational changes required for fusion Signup and view all the answers

What type of drug is Maraviroc and what is its main warning?

Entry inhibitor; hepatotoxicity warning Signup and view all the answers

Which component is NOT part of the combination drug Stribild?

Dolutegravir Signup and view all the answers

What role does integrase play in HIV replication?

It aids in the transfer of viral DNA to the host cell's genome Signup and view all the answers

Which strain of Influenza is primarily responsible for pandemics?

Influenza A Signup and view all the answers

What is a notable characteristic of Adamantines in relation to Influenza A?

Resistance to Adamantines is now common among mutants Signup and view all the answers

Which of the following options correctly describes the drugs in Genvoya?

Elvitegravir, Emtricitabine, Tenofovir alafenamide, Cobicistat Signup and view all the answers

What classification criteria is used for Influenza virus strains?

Core proteins, species of origin, and geographic site of isolation Signup and view all the answers

Study Notes

Pharmacology 3 - Anti-Viral Drugs

Viruses are classified as either exceptionally complex aggregations of non-living chemicals or exceptionally simple living microbes.
Viruses are obligate intracellular parasites, relying on the host cell's synthetic processes for replication.
Effective antiviral agents either block viral entry/exit from the cell or act intracellularly to inhibit viral replication
Non-selective inhibitors of virus replication may harm host cells due to toxicity.
Treatment periods vary, from brief monotherapy (e.g., acyclovir for herpes simplex virus) to prolonged dual therapy (e.g., interferon alfa/ribavirin for HCV), or indefinite multiple drug therapy (e.g., HIV).

Virus Structure

Viruses have an outer envelope composed of host cell components (e.g., membranes, endoplasmic reticulum, nuclear envelope).
The envelope surrounds a capsid, a shell of identical capsomeres.
The capsid protects the viral nucleic acid (either DNA or RNA, but not both).

Steps for Viral Replication

Adsorption: The virus attaches to the host cell surface.
Entry: The viral nucleic acid enters the host cell.
Replication: Viral DNA or RNA is replicated, and viral proteins are produced.
Assembly: New viral particles are assembled.
Release: The host cell lyses, releasing the newly made viruses.

Retrovirus Replication

Retroviruses have RNA genomes.
Reverse transcriptase converts viral RNA into DNA.
The proviral DNA integrates into the host cell's DNA.
The host cell's machinery transcribes viral DNA into viral RNA and translates it into viral proteins.
New viruses bud from the host cell membrane.

Antiviral Drugs Based on Drug Mechanism

Inhibitors of DNA Polymerase: Nucleoside analogs such as acyclovir, valacyclovir, famciclovir, and penciclovir are used against herpes simplex virus and varicella-zoster virus, stopping viral DNA synthesis by incorporating into viral DNA chain.
Inhibitors of Reverse Transcriptase: Nucleoside analogs such as zidovudine and didanosine are used against HIV, interfering with viral RNA to DNA conversion.
Inhibitors of Protease: Drugs like Atazanavir, Darunavir, are used against HIV to prevent viral protein assembly.
Inhibitors of Neuraminidase: Drugs such as oseltamivir and zanamivir are used against influenza viruses, preventing the release of virions from infected cells.
Other antivirals: Drugs like Foscarnet and cidofovir are used to combat a range of viruses, acting through alternative means, including non-competitive inhibition of multiple viral polymerases.

Anti-Herpes Simplex Virus (HSV) and Varicella-Zoster Virus (VZV) Agents

Acyclovir, Valacyclovir, Famciclovir, and Penciclovir are antiviral agents used to treat various HSV and VZV infections, acting intracellularly as inhibitors of viral replication.
Docosanol and trifluridine are also utilized to target these viruses for symptomatic relief.

Anti-Cytomegalovirus (CMV) Agents

Ganciclovir, valganciclovir, Foscarnet, and cidofovir are used to treat CMV infections. These act differently to prevent viral replication.

Clinical Uses of Acyclovir

Used to treat different forms of HSV infections (gingivostomatitis, genital herpes) and VZV (shingles).
It's the drug of choice for severe or difficult HSV infections, such as encephalitis or severe HSV outbreaks in HIV patients.

Acyclovir Pharmacokinetics

Oral bioavailability is poor (15-20%) but unaffected by food.
Cmax occurs 1.5-2 hours after oral administration.
Valacyclovir is a prodrug, absorbed better and given less frequently.
IV formulation used for serious HSV infections (e.g., encephalitis).
Excreted primarily via glomerular filtration and tubular secretion. Half-life is 3 hours in patients with normal renal function, and 20 hours in those with anuria.
Topically, high concentrations are produced in lesions, but systemic absorption is minimal. CSF concentrations reach 50% of serum levels.

Adverse Effects of Antiviral Drugs

Acyclovir: Nephrotoxicity can occur, particularly with high IV doses, which may be prevented with proper hydration. Other effects include CNS effects like seizures, tremors, and more common side effects such as nausea, diarrhea, and rashes.
Ganciclovir: Myelosuppression and, to a lesser degree, other adverse effects (nausea, diarrhea) and CNS toxicity. Toxicity may be increased by concurrent use of other immunosuppressants (e.g., zidovudine).
Foscarnet: Nephrotoxicity (acute interstitial nephritis), especially at high doses, and potential electrolyte imbalances (hypocalcemia) may occur if used with other nephrotoxic drugs like diuretics. Gastrointestinal intolerance can be a limiting factor for oral absorption.
Other Antivirals: Adverse effects vary depending on the specific drug.

Antiretroviral Agents

Combination therapy is essential to prevent resistance.
Key classes include NRTIs (nucleoside reverse transcriptase inhibitors), NNRTIs (non-nucleoside reverse transcriptase inhibitors), protease inhibitors, entry/fusion inhibitors, and integrase inhibitors

Other Anti-Viral Drugs

Influenza: Amantadine and rimantadine (adamantines, used for influenza A but not influenza B virus), and neuraminidase inhibitors (oseltamivir and zanamivir).
Hepatitis B: interferon-α, lamivudine, adefovir dipivoxil, entecavir, telbivudine, tenofovir.
Hepatitis C: Direct-acting antiviral agents (DAAs) are used.

Clinical Considerations

Tropism testing is needed before beginning Maraviroc treatment.
Patients may require concurrent use of a booster for some protease inhibitors (e.g., ritonavir, cobicistat).
Dosage adjustments are often necessary depending on renal function.

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Description

Test your knowledge on the mechanisms and classifications of antiretroviral agents. This quiz covers essential concepts related to HIV treatment, including the roles of various drug classes and their mechanisms of action. Dive into specifics about NRTIs, integrase inhibitors, and important considerations for patient management.