Antivirals Practice Questions

Q: A 65-year-old patient presents with symptoms of bone pain, anemia, hypercalcemia, and renal impairment. A bone marrow biopsy confirms the diagnosis of multiple myeloma. The patient is started on a treatment regimen. Which of the following treatments is most likely associated with the reactivation of herpes zoster?

Bortezomib. ***Bortezomib*** - **Bortezomib**, a **proteasome inhibitor**, is known to increase the risk of herpes zoster reactivation in patients with multiple myeloma due to its immunosuppressive effects. - Prophylaxis with antiviral agents (e.g., acyclovir) is often recommended during bortezomib treatment to prevent this complication. - Studies show herpes zoster incidence of 10-15% in bortezomib-treated patients without prophylaxis. *Lenalidomide* - While lenalidomide is an **immunomodulatory drug** used in multiple myeloma, it is generally associated with a lower risk of herpes zoster reactivation compared to proteasome inhibitors. - It primarily acts by inhibiting angiogenesis and stimulating T-cell and natural killer cell activity. *Daratumumab* - **Daratumumab** is a **monoclonal antibody** targeting CD38 on myeloma cells, leading to their destruction. - Although it has immunosuppressive effects, it is less commonly associated with herpes zoster reactivation than bortezomib. *Melphalan* - **Melphalan** is an **alkylating agent** used in chemotherapy for multiple myeloma, particularly in conditioning regimens for stem cell transplantation. - While it causes myelosuppression and general immunosuppression, the direct association with herpes zoster reactivation is not as prominent or specific as with bortezomib. *Dexamethasone* - **Dexamethasone** is a **corticosteroid** commonly used in combination regimens for multiple myeloma (e.g., RVD, VCD). - While corticosteroids cause immunosuppression and can increase infection risk, the specific association with herpes zoster reactivation is less pronounced than with bortezomib.

Q: A patient with HIV who is currently on antiretroviral therapy consisting of zidovudine, lamivudine, and nevirapine is diagnosed with tuberculosis. Considering potential drug interactions, which of the following TB drugs should be changed in this patient?

Rifampicin. **Rifampicin** - **Rifampicin** is a potent **CYP450 enzyme inducer**, which significantly increases the metabolism of **nevirapine**, a non-nucleoside reverse transcriptase inhibitor (NNRTI), leading to subtherapeutic levels and potential treatment failure. - In patients on **nevirapine-based ART**, **rifampicin** is typically avoided or replaced with other rifamycins (like **rifabutin**), or the antiretroviral regimen is switched to one that is less affected by enzyme induction. *Isoniazid* - **Isoniazid** does not have significant, clinically problematic interactions with the antiretroviral regimen mentioned (zidovudine, lamivudine, nevirapine), and is generally well-tolerated. - It is a cornerstone of TB treatment and is usually continued without dose adjustment or substitution in this scenario. *Pyrazinamide* - **Pyrazinamide** is part of the standard first-line TB treatment regimen and does not have clinically significant drug interactions with zidovudine, lamivudine, or nevirapine. - It can be safely continued without dose adjustment in patients on this ART regimen. *Ethambutol* - **Ethambutol** primarily causes **optic neuritis** as a side effect and does not have significant pharmacokinetic interactions with the antiretroviral drugs listed. - Its use in TB treatment alongside this ART regimen is generally safe and does not require a change. *Streptomycin* - **Streptomycin** is an **aminoglycoside antibiotic** primarily used for multi-drug resistant TB or in specific situations, and its main toxicity is **ototoxicity** and **nephrotoxicity**. - It does not have known significant drug interactions with zidovudine, lamivudine, or nevirapine that would necessitate a change.

Q: A 28-year-old primigravid woman at 38 weeks' gestation is brought to the emergency department in active labor. She has not had regular prenatal care. She has a history of HIV infection but is not currently on antiretroviral therapy. Her previous viral load is unknown. Treatment with intravenous zidovudine is begun to reduce perinatal transmission of the virus. Which of the following processes is most likely affected by this drug?

Elongation of viral DNA. ***Elongation of viral DNA*** - **Zidovudine (AZT)** is a **nucleoside reverse transcriptase inhibitor (NRTI)** that mimics thymidine and gets incorporated into the growing viral DNA strand by HIV reverse transcriptase. - Its incorporation causes **chain termination** because it lacks a 3'-hydroxyl group, preventing further phosphodiester bond formation and thus inhibiting the elongation of viral DNA. *Cleavage of viral polypeptides* - This process is targeted by **protease inhibitors**, which prevent the HIV protease enzyme from cleaving large precursor polypeptides into functional proteins. - Zidovudine's mechanism of action is distinct from protease inhibition. *Fusion of virus with T cells* - This step is inhibited by **fusion inhibitors**, which block the interaction between the viral envelope glycoprotein (gp120/gp41) and the host cell receptors (CD4 and co-receptors like CCR5 or CXCR4). - Zidovudine does not interfere with viral entry into the host cell. *Integration of viral genome* - This process is targeted by **integrase inhibitors**, which prevent the HIV integrase enzyme from inserting the viral DNA into the host cell's genome. - Zidovudine acts earlier in the viral life cycle by inhibiting reverse transcription, before integration occurs. *Action of viral RNA polymerase* - HIV is a retrovirus and uses **reverse transcriptase** to convert its RNA genome into DNA, not a viral RNA polymerase for genome replication. - While host RNA polymerase II is used to transcribe viral DNA into mRNA, zidovudine specifically targets reverse transcriptase, not RNA polymerase.

Q: The physician recommends that the patient receive an influenza vaccine. The patient becomes nervous and reports that he has never received an influenza vaccination because of an allergy to eggs. The allergy was diagnosed many years ago, after he developed hives upon eating scrambled eggs. Which of the following is the most appropriate next step in management?

Administer inactivated influenza vaccine. ***Administer inactivated influenza vaccine*** - The patient's reported allergy to eggs (hives after eating scrambled eggs) is a **mild allergic reaction** and does not contraindicate receiving an inactivated influenza vaccine. - The **ACIP guidelines** state that individuals with a history of **mild egg allergy** can safely receive any FDA-approved influenza vaccine suitable for their age and health status. *Administer oseltamivir* - **Oseltamivir** is an antiviral medication used for the treatment or prevention of influenza, not for vaccination. - Administering oseltamivir before potential exposure or as a treatment is not the same as providing the patient with the recommended influenza vaccine. *Prescribe oseltamivir for standby emergency treatment* - This option involves prescribing an antiviral for potential future use, which is not the primary goal of vaccinating against influenza and does not address the patient's need for immunization. - Standby treatment does not provide the **prophylactic benefits** of vaccination. *Administer influenza immunoglobulins* - **Influenza immunoglobulins** are not a standard or routine method for providing protection against seasonal influenza in healthy individuals. - They are typically reserved for specific situations involving severe immunocompromised patients or high-risk exposures. *End the examination without additional measures* - This would mean neglecting the recommendation for influenza vaccination and not addressing the patient's misconception about egg allergy. - Healthcare providers should take steps to ensure patients receive recommended vaccinations, especially when the perceived contraindication is manageable.

Q: A 35-year-old male is found to be infected with an HIV strain resistant to saquinavir and zidovudine. Which of the following best explains the drug resistance observed in this patient?

pol mutation. ***Correct: pol mutation*** - Saquinavir is a **protease inhibitor** and zidovudine is a **reverse transcriptase inhibitor (NRTI)**. Both target enzymes encoded by the **pol gene** in HIV. - Mutations in the **pol gene** alter the structure of protease and reverse transcriptase enzymes, preventing drug binding and leading to resistance. - This is the direct molecular mechanism explaining resistance to both drugs in this patient. *Incorrect: HBV co-infection* - **HBV co-infection** can complicate HIV treatment and lead to liver damage, but it does not directly cause resistance to antiretroviral drugs. - While it may influence overall treatment strategy (e.g., choosing drugs active against both viruses), it does not explain the specific drug resistance mechanism observed. *Incorrect: env mutation* - The **env gene** encodes HIV **envelope proteins (gp120 and gp41)**, which are crucial for viral entry into host cells. - Mutations in env typically affect **viral tropism** (CCR5 vs CXCR4 usage) or immune evasion, not resistance to protease or reverse transcriptase inhibitors. *Incorrect: HIV evasion of host response* - HIV's ability to evade the **host immune response** (through high mutation rate, latency, and immune cell destruction) is a general mechanism for chronic infection. - This does not specifically explain resistance to particular antiretroviral drugs, which results from mutations in the viral proteins that drugs target. *Incorrect: CCR5 mutation* - **CCR5** is a host coreceptor that HIV uses to enter cells; a mutation in this gene (e.g., CCR5-Δ32 deletion) can confer natural resistance to HIV infection. - However, **host** CCR5 mutations do not cause resistance to HIV drugs like saquinavir or zidovudine, which target **viral enzymes**, not host entry receptors.

Question 1

A 65-year-old patient presents with symptoms of bone pain, anemia, hypercalcemia, and renal impairment. A bone marrow biopsy confirms the diagnosis of multiple myeloma. The patient is started on a treatment regimen. Which of the following treatments is most likely associated with the reactivation of herpes zoster?

Accepted Answer

Bortezomib

Answer

Lenalidomide

Answer

Daratumumab

Answer

Melphalan

Answer

Dexamethasone

Question 2

A patient with HIV who is currently on antiretroviral therapy consisting of zidovudine, lamivudine, and nevirapine is diagnosed with tuberculosis. Considering potential drug interactions, which of the following TB drugs should be changed in this patient?

Accepted Answer

Rifampicin

Answer

Isoniazid

Answer

Ethambutol

Answer

Streptomycin

Answer

Pyrazinamide

Question 3

A 28-year-old primigravid woman at 38 weeks' gestation is brought to the emergency department in active labor. She has not had regular prenatal care. She has a history of HIV infection but is not currently on antiretroviral therapy. Her previous viral load is unknown. Treatment with intravenous zidovudine is begun to reduce perinatal transmission of the virus. Which of the following processes is most likely affected by this drug?

Accepted Answer

Elongation of viral DNA

Answer

Cleavage of viral polypeptides

Answer

Fusion of virus with T cells

Answer

Integration of viral genome

Answer

Action of viral RNA polymerase

Question 4

The physician recommends that the patient receive an influenza vaccine. The patient becomes nervous and reports that he has never received an influenza vaccination because of an allergy to eggs. The allergy was diagnosed many years ago, after he developed hives upon eating scrambled eggs. Which of the following is the most appropriate next step in management?

Accepted Answer

Administer inactivated influenza vaccine

Answer

Administer oseltamivir

Answer

Prescribe oseltamivir for standby emergency treatment

Answer

Administer influenza immunoglobulins

Answer

End the examination without additional measures

Question 5

A 35-year-old male is found to be infected with an HIV strain resistant to saquinavir and zidovudine. Which of the following best explains the drug resistance observed in this patient?

Accepted Answer

pol mutation

Answer

HBV co-infection

Answer

env mutation

Answer

HIV evasion of host response

Answer

CCR5 mutation

Antivirals — MCQs

Antivirals — MCQs

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