Antiviral Drugs Quiz

Questions and Answers

What is the primary means of preventing influenza?

Antiviral drugs

Vaccines (correct)

Neuraminidase inhibitors

Antibacterial drugs

What is the enzyme that neuraminidase inhibitors target in influenza A and B viruses?

DNA polymerase

Reverse transcriptase

Neuraminidase (correct)

Protease

What is the benefit of starting neuraminidase inhibitor therapy as early as possible for patients with confirmed or suspected influenza?

Reducing the risk of complications (correct)

Preventing the spread of influenza

Shortening the duration of illness by several weeks

Increasing the severity of symptoms

What is the role of neuraminidase in the life cycle of influenza viruses?

It enables the release of virions from infected cells Signup and view all the answers

What is the effect of neuraminidase on the respiratory tract mucous?

It inactivates the mucous to allow the spread of virions Signup and view all the answers

When are neuraminidase inhibitors most beneficial in reducing symptom severity and duration of illness?

If given within 48 hours of the onset of symptoms Signup and view all the answers

What type of patient should receive neuraminidase inhibitor therapy?

Patients who are hospitalized or at higher risk of complications Signup and view all the answers

What is the effect of neuraminidase inhibitors on the complications of influenza?

They reduce the risk of complications Signup and view all the answers

What is the unique mechanism of action of Baloxavir Marboxil (Xofluza)?

Targets ribonuclease activity that affects transcription of viral RNA Signup and view all the answers

What is the primary reason the CDC recommended against prophylaxis for influenza?

Due to risk of resistance Signup and view all the answers

What is the main advantage of valacyclovir over acyclovir?

Higher oral bioavailability Signup and view all the answers

Which of the following is NOT a nucleoside analogue used to treat herpesvirus infections?

Amoxicillin Signup and view all the answers

What is the main benefit of using antiviral medications to treat genital herpes?

Prevents replication of HSV and reduces pain and symptoms Signup and view all the answers

Which medication has the greatest bioavailability for treating herpesvirus infections?

Famciclovir Signup and view all the answers

What is the primary indication for using Baloxavir Marboxil (Xofluza)?

Treatment of influenza A and B Signup and view all the answers

What is the benefit of the Zostavaz vaccine for older adults?

Reduces the incidence and severity of herpes zoster infections Signup and view all the answers

What is the primary mechanism of action of NRTIs in the treatment of HIV?

Inhibiting the reverse transcription of viral RNA to DNA Signup and view all the answers

What is the benefit of using HAART in the treatment of HIV infection?

Markedly reducing viral load and improving survival Signup and view all the answers

What enzyme is responsible for cleaving polyproteins into smaller functional proteins during viral maturation?

HIV protease Signup and view all the answers

What is the result of the incorporation of viral DNA into the host genome?

Transcription and translation of viral DNA Signup and view all the answers

What is the primary mechanism of action of PIs in the treatment of HIV?

Inhibiting the cleavage of polyproteins during viral maturation Signup and view all the answers

What is the goal of recent developments in HAART regimens?

Developing regimens that require only a few doses each day Signup and view all the answers

What is the function of reverse transcriptase in the replication of HIV?

Converting viral RNA to DNA Signup and view all the answers

What is the result of the entry of HIV into CD4 cells?

Reverse transcription of viral RNA to DNA Signup and view all the answers

What is the primary mechanism of action of enfuvirtide?

It blocks the fusion of HIV with CD4 cells. Signup and view all the answers

Which of the following statements about non-nucleoside reverse transcriptase inhibitors (NNRTIs) is TRUE?

They do not bind to the active site of the HIV protease enzyme. Signup and view all the answers

What is the benefit of using maraviroc in HIV treatment?

It is active against HIV strains resistant to RTIs and PIs. Signup and view all the answers

What is the mechanism of action of raltegravir?

It prevents the incorporation of viral DNA into host DNA. Signup and view all the answers

Which of the following is a unique characteristic of efavirenz?

It is teratogenic and should be avoided in pregnancy. Signup and view all the answers

What is the main mechanism of action of protease inhibitors (PIs)?

They bind to the active site of the HIV protease enzyme and inhibit its activity. Signup and view all the answers

What is the advantage of using a regimen containing raltegravir for initial HIV treatment?

It is recommended by recent guidelines for initial treatment. Signup and view all the answers

Which of the following is a characteristic of atazanavir and darunavir?

They are the preferred PIs for treating HIV today. Signup and view all the answers

What is the primary indication for using enfuvirtide?

Treatment of drug-resistant HIV strains. Signup and view all the answers

What is the route of administration for enfuvirtide?

Subcutaneous Signup and view all the answers

What is the role of ritonavir in boosted therapy?

It inhibits the metabolism of other PIs, increasing their plasma levels and duration. Signup and view all the answers

What is a common side effect of enfuvirtide?

Injection site reactions Signup and view all the answers

What is the common adverse effect of nevirapine?

Rash is the most common side effect. Signup and view all the answers

Why is efavirenz avoided in pregnancy?

Because it is teratogenic. Signup and view all the answers

What is the name of the combo drug product containing ritonavir and another PI?

Kaletra Signup and view all the answers

What is the unique characteristic of HIV protease?

It is responsible for maturation of the virus. Signup and view all the answers

Study Notes

Antiviral Drugs

Antibacterial and antifungal drugs have little to no effect on viral infections
Compounds have been developed to treat some viral infections (e.g., HIV, influenza, and hepatitis)
Antiviral drugs work in a variety of ways (e.g., prevent replication of viral nucleic acid; inhibit entry, uncoating, or release of virus)

Influenza

One of the most common causes of infectious disease-related deaths
Vaccines are the primary means of prevention
Neuraminidase inhibitors are useful for prophylaxis, during outbreaks, can shorten duration of illness in infected persons and prevent complications

Neuraminidase Inhibitors

Reduce complications including otitis media (OM) and pneumonia (PNA)
Drug therapy should be started as early as possible for any patient with confirmed or suspected influenza who is hospitalized, has severe illness, or is at higher risk of complications
Most beneficial in reducing symptom severity and duration of illness if given < 3 days after onset, preferably within 48 hours
May still provide benefit in reducing respiratory failure and death in pregnant women if started 3-4 days after onset

Prophylaxis

70-90% effective in preventing influenza, useful adjuncts to vaccines
CDC recommended against prophylaxis because of risk of resistance
Only prophylaxis, populations at risk of complications and control institutional outbreaks

Baloxavir Marboxil (Xofluza)

Single dose PO treatment for influenza A and B
First-in-class medication
Unique mechanism of action (MOA) targets ribonuclease activity that affects transcription of viral RNA
Approved in the US in 2018
Potentially less side effects vs oseltamivir

Herpesviruses

Cytomegalovirus (CMV) infections in immunocompetent are usually asymptomatic
CMV retinitis, esophagitis, and colitis usually seen in immunocompromised patients

Drugs for Herpesviruses

Nucleoside analogues:
- Acyclovir (Zovirax): IV acyclovir most effective for serious herpesvirus infections, including encephalitis and infections in immunocompromised patients; topical acyclovir can be used to treat genital herpes and mild mucocutaneous infections
- Ganciclovir (Cytovene)
- Trifluridine (Viroptic)
- Valacyclovir (Valtrex): prodrug that gets rapidly converted to acyclovir by intestinal and hepatic enzymes, more completely absorbed (55%)
- Famciclovir (Famvir): has the greatest bioavailability (80%)
Other drugs:
- Foscarnet (Foscavir)

Treating Genital Herpes

When given orally for genital herpes, prevents replication of HSV and reduces pain and other symptoms of acute infection
Shortens time to healing of lesions, reduces the amount of viral shedding
Does not eliminate the virus, recurrent episodes are common (can be treated with lesser doses)

Treating Shingles

When given orally for shingles, shortens duration of acute illness and pain and lowers incidence of postherpetic pain
Famciclovir and valacyclovir are more effective than acyclovir
Newer drugs have less frequent administration, higher serum levels
A vaccine is now available (Zostavaz) that reduces the incidence and severity of herpes zoster infections in older adults

Human Immunodeficiency Virus (HIV)

Many remarkable advancements have been made in treating HIV infection and AIDS
Combined use of 2 or more drugs from different classes have been shown to markedly reduce viral load and improve survival
Multidrug treatment called highly active antiretroviral therapy (HAART)

HAART

Initially were complicated regimens requiring multiple doses of several drugs every day
Recent emphasis on developing drug regimens that require only a few doses each day or even a single pill (like Atripla)
Guidelines continue to evolve as new regimens are developed and testing

Pathophysiology of HIV

Enters CD4 cells, viral RNA produced double-stranded DNA via reverse transcriptase
Viral DNA enters host cell nucleus and gets incorporated into host genome via HIV integrase
Eventually, the viral DNA gets transcribed/translated to produce polyproteins that get packed into immature virions
HIV protease cleaves polyproteins into smaller functional proteins during viral maturation where virions get released into plasma

Drug Classes

1. Nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs)
1. Non-nucleoside reverse transcriptase inhibitors (NNRTIs)
1. Protease inhibitors (PIs)
1. Fusion and entry inhibitors
1. Integrase inhibitors

Non-nucleoside Reverse Transcriptase Inhibitors (NNRTIs)

Do not require metabolic activation and are not incorporated into viral DNA
Efavirenz is the most potent NNRTI available, preferred for initial treatment of people with HIV because it can be taken qd
Nevirapine is used in combo with two NRTIs
Delaviridine, not recommended for most patients, has lower antiviral activity compared to others in this class

Protease Inhibitors (PIs)

HIV protease is responsible for maturation of the virus
Protease inhibitors bind to the active site of the enzyme and inhibit its activity, resulting in production of immature, non-infectious virus particles
First PI introduced in 1995, ushered in a new era of HIV treatment
Newer PIs like atazanavir are better tolerated and have improved pharmacokinetic properties
Atazanavir and darunavir are the preferred PIs for treating HIV today

Fusion and Entry Inhibitors

Enfuvirtide (Fuzeon [T-20]): large peptide that binds to HIV glycoprotein 41 and blocks fusion process; not active when given orally, must be injected sq bid
Maraviroc (Selzentry)
Newer drugs that inhibit fusion and entry of HIV
Active against HIV strains resistant to RTIs and PIs
Approved to treat HIV infection caused by drug-resistant strains

Integrase Inhibitors

Integrase incorporates viral DNA formed by reverse transcriptase into DNA of CD4 cells
Raltegravir (Isentress) is the first integrase strand inhibitor approved to treat HIV
Works by preventing DNA strand transfer
Potent in vitro activity against wild-type and MDR HIV strains
Recent recommendations for initial treatment include a regimen containing raltegravir

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Description

This quiz covers the basics of antiviral drugs, including their mechanism of action and effectiveness against various viral infections such as HIV, influenza, and hepatitis.