Pharm Antivirals
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A 74-year-old diabetic woman was brought to the emergency room with fever (102.7°F), shaking chills, cough, headache and malaise. Physical examination showed profound dyspnea and rales were audible on auscultation on both lungs. Chest x-ray showed bilateral infiltrates and blood gas analysis revealed significant hypoxia. A gram stain of the sputum showed no bacteria. Fluorescent antibodies identified influenza A virus on cells of nasal aspirates. An appropriate therapy was started which included a drug that acts by inhibiting viral uncoating. Which of the following drug was most likely prescribed?
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Foscarnet
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Ganciclovir
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Zidovudine
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Amantadine
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Cidofovir
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Indinavir
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About This Quiz
This quiz titled 'Pharm Antivirals' assesses knowledge on antiviral drugs, their mechanisms, and clinical applications. It includes scenarios on drug effects, adverse reactions, and treatment failures, relevant for medical students and healthcare professionals.
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- 2.
A 24-year old man visited his physician complaining of painful ulcers on his penis. Upon examination multiple rounded translucent vesicles were seen on the penis gland, intermixed with superficial, circular ulcers which were very painful to the touch. Regionallimphoadenopathy was also present. A preliminary diagnosis was made. Which of the following drugs was most likely prescribed for the treatment of the patient’s disorder?
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Penicillin G
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Doxycycline
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Metronidazole
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Acyclovir
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Ketoconazole
Correct Answer
A. AcyclovirExplanation
Learning objective: outline the therapeutic uses of acyclovir.
Answer: D
The type of the lesion strongly suggests genital herpes. Other genital diseases are unlikely, as
explained below. Acyclovir is the drug of choice for genital herpes. Oral therapy speed up the
healing and reduces the frequency of reactivation episodes.
A) Penicillin G is effective in case of primary syphilis. The disease causes a red genital papule
that soon erodes to form a ulcer. However the ulcer is painless.
B) Doxycycline is the drug of choice for granuloma inguinale, a disease caused by
Calymmatobacterium granulomatis, a gram-negative rod. The initial lesion of this disease is a
painless nodule that slowly develops into a rounded, elevated granulomatous mass and finally
into a creeping, serpiginous ulcer.
C) Metronidazole is the drug of choice for trichomoniasis. The disease can cause urethritis but
not ulcers on the penis.
E) Topical miconazole is used to treat genital candidiasis. Even if the disease can sometimes
cause vesicles or erosions of the penis it is symptomless in men, in most cases.Rate this question:
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- 3.
A 43-year-old man with AIDS presented to his physician with a complaint of multiple painful ulcers in tongue and palate. Exfoliative cytology was done which led to the diagnosis of herpes simplex infection, and a therapy with oral acyclovir was initiated. Two weeks later no improvement was seen and the dose of the drug was increased but without success. Which of the following was most likely the cause of failure of acyclovir therapy?
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Mutation of aspartate protease
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Viral transpeptidase deficiency
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Viral thymidine kinase deficiency
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Viral neuraminidase deficiency
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Mutation of reverse transcriptase
Correct Answer
A. Viral thymidine kinase deficiencyExplanation
Learning objective: explain the most common reason of failure of acyclovir therapy.
Answer: C
Acyclovir resistance is the most common cause of failure of acyclovir therapy. Acyclovir resistant
strains of HSV and VZV arise chiefly from mutations in the thymidine kinase gene that result in
little or no production of the enzyme. Since viral thymidine kinase is essential for conversion of
acyclovir to active derivatives, resistance to the drug ensues. Resistant strains are most
commonly reported in severely immunocompromised patients receiving extended course of the
drug, like in the present case.
A, B, D, E) All the mentioned enzymes are not involved in the mechanism of action of the drug,
and therefore their deficiency cannot be the cause of resistance to the drug action.Rate this question:
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- 4.
A 23-year-old woman with AIDS came to the hospital complaining of floating spots in her vision and difficulty in reading. Funduscopic examination revealed the presence of alternating areas of hemorrhagic tissue and fluffy, white patches in the proximity of retinas of both eyes consistent with hemorrhagic retinitis. Which of the following drugs was most likely prescribed for the treatment of the patient’s ocular disorder?
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Amantadine
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Ribavirin
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Ganciclovir
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Lopinavir
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Gentamicin
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Doxycycline
Correct Answer
A. GanciclovirExplanation
Learning objective: outline the therapeutic uses of gancyclovir.
Answer: C
A hemorrhagic retinitis in an AIDS patient strongly suggests the diagnosis of cytomegalovirus
retinitis, which accounts for more than 75% of cytomegalovirus end-organ disease in HIV
positive patients. Treatment options for cytomegalovirus retinitis include ganciclovir, foscarnet,
and cidofovir. These drugs are administered IV or by intraocular injections. Fomivirsen is
another drug used for cytomegalovirus retinitis and administered only by intraocular injection.
A, B, D) These antiviral drugs are not used for cytomegalovirus retinitis.
E, F) These drugs are not antiviral agents.Rate this question:
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- 5.
A 23-year-old man had recurrent genital herpes which was effectively treated each time by acyclovir. The patient asked his physician why the treatment was not able to prevent recurrence. Which of the following was most likely the answer of the physician?
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Acyclovir has a very short duration of action
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Recurrence is due to a new contact with infected partners
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Antiviral drugs have no effect on the latent state of viral diseases
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Recurrence is due to a hypersensitivity reaction to viral proteins
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Resistant to acyclovir is the rule after one cycle of therapy
Correct Answer
A. Antiviral drugs have no effect on the latent state of viral diseasesExplanation
Learning objective: explain why antiviral drugs cannot prevent recurrence if viral diseases.
Answer: C
Herpes viruses replicate in the skin or mucous membrane at the initial site of infection, then
migrate up the neuron and become latent in the sensory ganglion cells. The virus can be
reactivated from the latent state by a variety of factors including sunlight, hormonal changes
trauma, stress an fever at which time it migrates down the neuron and replicates in the skin,
causing lesions. No currently available antiviral drug attacks viruses during latency but acts only
on actively replicating viruses.
A, B, D, E) (see explanation above)Rate this question:
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- 6.
A 32-year-old woman visited her physician complaining of some very painful blisters on her abdomen. Physical examination showed localized blisters on her left abdomen consistent with a varicella-zoster infection. A drug therapy was started. Which of the following enzymes was most likely inhibited by the administered drug?
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Transpeptidase
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DNA-polymerase
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Aspartate protease
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Reverse transcriptase
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Neuraminidase
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Integrase
Correct Answer
A. DNA-polymeraseExplanation
Learning objective: explain the mechanism of action of acyclovir.
Answer: B
Drugs for VZV infection include acyclovir, famciclovir and penciclovir. These drugs are
phosphorylated to the triphosphate derivatives which are potent inhibitors of both viral DNA and
mammalian DNA polymerase. However viral DNA polymerase is more sensitive to inhibition
than the DNA polymerase of the host cell.
A, C, D, E, F) These enzymes are not inhibited by acyclovir.Rate this question:
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- 7.
A 12-day-old, premature baby boy developed a poor feeding pattern, irritability and respiratory distress. His mother, who suffered several episodes of genital herpes, was admitted to labor with premature ruptures of the membranes. Physical examination of the baby revealed several small vesicular skin lesions located on the scalp and a dendritic keratitis was present on both eyes. Which of the following drugs was most likely included in the therapeutic treatment of this baby?
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Saquinavir
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Acyclovir
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Zidovudine
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Pentamidine
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Fluconazole
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Metronidazole
Correct Answer
A. AcyclovirExplanation
Learning objective: outline the therapeutic uses of acyclovir.
Answer: B
The history of the mother (several episodes of genital herpes) and the signs of the patient
(prematurity, respiratory distress, cutaneous vesicles) suggest that the baby was suffering from
congenital herpes, a disease that affects about 1 in 3000 live births and is acquired, in most
cases, during the passage through the birth canal. The diagnosis is confirmed by the finding of
dendritic keratitis, which is pathognomonic of herpetic keratocongiuntivitis. Antiherpes drugs
include acyclovir, several acyclovir congeners, foscarnet, ganciclovir, cidofovir and trifluridine.
Acyclovir is still the drug of choice for systemic treatment. Foscarnet and cidofovir can be used
for acyclovir resistant strains. Trifluridine can be used topically to managed the keratitis.
A, C) Saquinavir and zidovudine are antiretroviral drugs used only in HIV infection.
D, E, F) These drugs are not antiviral agents.Rate this question:
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- 8.
A 75-year-old patient was brought to the emergency room from a nursing home with chief complains of fever (102.8° F), cough, headache, malaise, anorexia and photophobia. Conventional antibiotic therapy was ineffective and three days later influenza virus was isolated from the sputum. Over the next week, three other nursing home patients developed similar symptoms. Vaccination and chemoprophylaxis were planned for all nursing home residents and staff. Which of the following drugs was most likely administered as a prophylactic measure?
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Acyclovir
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Foscarnet
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Ribavirin
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Ganciclovir
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Oseltamivir
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Zidovudine
Correct Answer
A. OseltamivirExplanation
Learning objective: outline the prophylactic use of neuraminidase inhibitors.
Answer: E
Vaccination plus chemoprophylaxis against influenza is advisable for residents of nursing
homes or other chronic care facilities and personnel who have extensive contacts with high risk
patients, like in the present case. Oseltamivir and zanamivir are inhibitors of neuraminidases
produced by influenza A an B viruses. These enzymes cleave sialic acid residues from cell
surface so promoting the release of newly formed virus from the surface of infected cells. Both
drugs cause a significant reduction of the symptoms of influenza A and B and are therefore
preferable to amantadine which is effective only against influenza A. Resistance to
neuraminidase inhibitors was quite uncommon till recently, but now rates of resistance to
oseltamivir among H1N1 virus (a subtype of influenza A) have risen abruptly and dramatically.
A, B, C, D, F) These drugs are not effective against influenza viruses.Rate this question:
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- 9.
The diagram below depicts a simplified pathway of the viral growth cycle: Which of the steps shown in the pathway is most likely inhibited by amantadine?
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A
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B
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C
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D
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E
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F
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G
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H
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I
Correct Answer
A. CExplanation
Answer: C
.Amantadine most likely acts by preventing uncoating, that is the separation of the viral core
from the outer structural components, that takes place after the fusion process.Rate this question:
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- 10.
A 5 year-old girl was admitted to the emergency room because of fever (102 F°) and disorientation in time and space. Soon after the admission the patient had a seizure. Ceftriaxone and dexamethasone were initiated but the next day the patient became lethargic and lapsed into a coma. Examination of the cerebrospinal fluid was normal and a CT scan of the brain revealed a decrease density in a small area of the right parietal lobe. Acyclovir IV was started and after 5 days of therapy the patient was alert, responsive and actively moving. The patient was most likely suffering from which of the following diseases?
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Neisseria meningitis
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Toxoplasma encephalitis
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Cryptococcal meningitis
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Cytomegalovirus encephalitis
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Herpes encephalitis
Correct Answer
A. Herpes encephalitisExplanation
Learning objective: outline the therapeutic uses of acyclovir.
Answer: E
The signs and symptoms of the patient suggested the presumptive diagnosis of bacterial
meningitis but the lack of efficacy of antibiotic therapy and the normal CSF rose the suspicion of
herpes simplex virus encephalitis, which is the most common sporadic viral infection of the
CNS. Acyclovir is the drug of first choice and the efficacy of the therapy confirms that the patient
was suffering from herpes encephalitis.
A) (see explanation above)
B, C) These diseases are quite rare in patients without HIV, and cannot be cured with antiviral
drugs.
D) Cytomegalovirus infection occur mainly in immunocompromised patients or is congenital,
and acyclovir is not active against CMV.Rate this question:
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- 11.
A 33-year-old woman with AIDS was recently diagnosed with cytomegalovirus retinitis. The ophthalmologist prescribed a drug that must be phosphorylated first by virusspecific enzymes, and then by host’s cell enzymes to become active. Which of the following drugs was most likely given?
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Foscarnet
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Ribavirin
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Ganciclovir
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Acyclovir
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Vidarabine
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Zidovudine
Correct Answer
A. GanciclovirExplanation
Learning objective: explain the mechanism of action of gancyclovir.
Answer: C
Ganciclovir and acyclovir are nucleoside analogs that must be phosphorylated first by virusspecific
enzymes. Both drugs are phosphorylated by a viral thymidine kinase in HSV infected
cells. Ganciclovir is also phosphorylated by a viral phosphotransferase in CMV infected cells.
This explains why both drugs are active against HSV by only ganciclovir is effective against
CMV.
A) This drug is used in cytomegalovirus retinitis, but it does not require activation by
phosphorylation.
D) Acyclovir has no activity against CMV infections.
E, F) These drugs are nucleoside analogs that must be phosphorylated to become active.
However phosphorylation is done, in these cases, by host’s cell enzymes only, and these drugs
are not effective against cytomegalovirus.Rate this question:
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- 12.
A 35-year-old man visited an ophthalmologist because of a foreign body sensation, lacrimation, photophobia and blurred vision in his left eye. Eye examination showed a conjunctival hyperemia and a branched lesion of corneal epithelium with terminal bulbs, swollen border and a central ulcer. A presumptive diagnosis was made and a topical therapy with eye drops was ordered. Which of the following drugs was most likely prescribed?
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Entecavir
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Lopinavir
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Nevirapine
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Zidovudine
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Trifluridine
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Oseltamivir
Correct Answer
A. TrifluridineExplanation
Learning objective: outline the therapeutic uses of trifluridine.
Answer: E
The symptoms and signs of the patient suggest that he was most likely affected by herpes
simplex keratitis, a common ocular disorder and one of the most frequent causes of blindness in
the U.S. The illness is usually treated topically and trifluridine eye drops 8-9 times/daily are
effective in most case. Occasionally oral acyclovir is indicated, especially for recurrent infection.
A) This is a drug for viral hepatitis
B, C, D) These are drugs for HIV infection
F) This is a drug for influenzaRate this question:
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- 13.
A 5-month-old baby girl born prematurely at 31weeks’ gestation was found to have bronchopulmonary dysplasia that needed oxygen use. Recently a respiratory syncytial virus outbreak occurred in the community and the pediatrician decided to order a drug to prevent the RSV infection. Which of the following drugs was most likely prescribed?
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Raltegravir
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Lopinavir
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Amantadine
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Lamivudine
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Palivizumab
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Trastuzumab
Correct Answer
A. PalivizumabExplanation
Learning objective: outline the prophylactic uses of palivizumab.
Answer: E
Palivizumab is a humanized monoclonal antibody that bind to the A antigen site on the F
surface protein of RSV. It is licenced for the prevention of RSV infection in high risk infant and
children such those with pulmonary dysplasia, like in the present case.
A, B, C, D, F) These drugs are not active against RSV infection.Rate this question:
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- 14.
A 34-year-man with AIDS was recently diagnosed with cytomegalovirus retinitis and a therapy with gancyclovir was started. Two weeks later the disease was not much improved and the ophthalmologist decided to add another drug that, unlike gancyclovir, can inhibit DNA polymerase directly without requiring activation by phosphorylation. Which of the following drugs was most likely prescribed?
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Acyclovir
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Lopinavir
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Ribavirin
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Foscarnet
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Trifluridine
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Nevirapine
Correct Answer
A. FoscarnetExplanation
Learning objective: explain the mechanism of action of foscarnet.
Answer: D
Foscarnet is an inorganic pyrophosphate analog that inhibits viral DNA polymerase, RNA
polymerase and HIV reverse transcriptase directly, without requiring activation by
phosphorylation. It is effective in the treatment of CMV retinitis and it is often given together with
gancyclovir since it has been shown that the combination is superior to either agent alone in
delaying the progression of retinitis.
A, B, C, E, F) All these drug are not effective in CMV retinitis.Rate this question:
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- 15.
A 71-year-old man was brought to the emergency room because of fever (103.2° F), chills, dyspnea, and generalized aches in the back and legs. Social history of the patient was significant for an outbreak of flu in the community. A clinical diagnosis of influenza was made and a treatment with oseltamivir was started. Which of the following actions most likely mediated the therapeutic effect of the drug in the patient?
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Prevention of virus release from infected cells
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Blockade of fusion of the virus with the host cell
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Inhibition of viral transcription
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Inhibition of viral proteolytic cleavage
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Inhibition of viral protein synthesis
Correct Answer
A. Prevention of virus release from infected cellsExplanation
Learning objective: explain the mechanism of action of oseltamivir.
Answer: A
Oseltamivir and zanamivir are inhibitors of neuraminidase an enzyme produced by influenza A
an B viruses. The enzyme cleaves sialic acid residues from cell surface so promoting the
release of newly formed virus from the surface of infected cells. By blocking the enzyme these
drugs inhibit virus release from the infected cells.
B, C, D, E) (see explanation above)Rate this question:
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- 16.
A 34-year-old man presented to the hospital with jaundice and complaints of incapacitating fatigue and vague intermittent abdominal pain for the past month. The patient had a history of IV drug abuse and of alcohol abuse. Hepatitis serologic tests were positive for HBsAg. Which of the following drugs would be appropriate for this patient?
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Enfuvirtide
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Saquinavir
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Amantadine
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Interferon alpha-2a
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Ganciclovir
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Foscarnet
Correct Answer
A. Interferon alpha-2aExplanation
Learning objective: outline the use of interferon alpha-2a in viral hepatitis B.
Answer: D
The chronic occurrence of jaundice in a young patient is suggestive of hepatitis and the
presence of hepatitis B surface antigen (HBsAG) in serum is diagnostic for HBV infection.
Approximately 5% of the world’s population is infected with HBV. The most prominent risk
factors associated with the disease include sexual contacts (> 50%) and injection drug use
(15%). Subclinical infections are common, but 25% of carriers develop chronic active hepatitis.
Worldwide one million deaths a year are attributed to HBV-related diseases, including
hepatocellular carcinoma. Drugs for the treatment of chronic hepatitis B include interferons,
adefovir, entecavir, tenofovir and lamivudine. These drugs are only moderately effective in
treating the disease since remission may be sustained but in many patients viral replication
reappears following cessation of therapy. Interferons are cytokines that posses antiviral,
immunomodulating and antiproliferative actions. They induce over two dozen proteins in the
host’s cells, which contribute to viral resistance through different mechanisms including:
1) inhibition of viral penetration and uncoating
2) inhibition of synthesis of viral DNA and RNA
3) inhibition of viral assembly and release
A, B, C, E, F) These antiviral drugs are not effective against hepatitis B.Rate this question:
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- 17.
A 31-year-old woman with a two year history of AIDS reported of watery, bloody diarrhea for approximately two weeks with accompanying abdominal pain. A colon biopsy revealed cytomegalovirus inclusions in the colonic mucosa. An IV therapy was started. Which of the following viral enzymes was most likely inhibited by the administered drug?
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DNA-polymerase
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Phosphotransferase
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RNA-polymerase
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HIV Protease
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Thymidine-kinase
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Neuraminidase
Correct Answer
A. DNA-polymeraseExplanation
Learning objective: explain the mechanism of action of gancyclovir.
Answer: A
In immunocompromised patient cytomegalovirus infection is a major cause of morbidity and
mortality. The infection can cause an ulcerative disease of the colon, like in the present case.
Gancyclovir is a drug of choice for CMV infection and was most likely administered to the
patient. The drug is phosphorylated by a CMV phosphotransferase or by a HSV thymidine
kinase to the corresponding nucleotide which can inhibit DNA polymerase of CMV, HSV and
VZV, so blocking viral DNA synthesis.
B, C, D, E, F) These enzymes are not inhibited by gancyclovir.Rate this question:
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- 18.
A 71-year-old woman was admitted to the hospital with a 2-day history of progressive dyspnea, fever, cough and wheezing. Chest radiograph was normal but a bronchoscopy showed marked erythema of the trachea and bronchi, with multiple ulcerations. A bronchial biopsy confirmed the diagnosis of herpetic tracheobronchitis. The patient received IV acyclovir for 3 days but no improvement was seen. Resistance to acyclovir was suspected and an alternative drug was given IV. Which of the following drugs was most likely administered?
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Foscarnet
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Saquinavir
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Amantadine
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Zidovudine
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Trifluridine
Correct Answer
A. FoscarnetExplanation
Learning objective: outline the therapeutic uses of foscarnet.
Answer: A
Herpetic tracheobronchitis has been documented in both immunocompromised and
immunocompetent individuals. Normal hosts typically are elderly individuals. Early detection of
herpetic tracheobronchitis appears critical so that acyclovir, which is a drug of first choice for
HSV infections, can be given during the time of peak viral replication, which tends to coincide
with symptomatic clinical illness. The most common cause of failure of acyclovir therapy is the
presence of thymidine kinase deficient strains of HSV. Since acyclovir must be phosphorylated
by a viral thymidine-kinase to become a nucleotide analog which inhibits viral DNA-polymerase,
these strains are acyclovir-resistant. In this case foscarnet, which directly inhibits viral DNApolymerase,
represents an useful alternative.
B, C, D) Saquinavir, amantadine and zidovudine are not active against HSV.
E) Trifluridine is effective against HSV but is very toxic and therefore is used only topically.Rate this question:
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- 19.
A 38-year-old woman suffering from chronic hepatitis B started a treatment with a drug that is able to inhibit several steps of hepatitis B virus replication including uncoating, early transcription, translation, assembly and release. Which of the following drugs was most likely administered?
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Lamivudine
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Entecavir
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Interferon alpha-2a
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Tenofovir
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Ribavirin
Correct Answer
A. Interferon alpha-2aExplanation
Learning objective: explain the mechanisms of antiviral action of interferons.
Answer: C
Interferons are drugs that can inhibit several steps of HBV replication including uncoating, early
transcription, translation, assembly and release. The inhibition of translation of viral proteins
seems the main mechanism.
A, B, D, E) These drugs are effective in viral hepatitis B, but they cannot inhibit multiple steps of
the viral growth cycle.Rate this question:
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- 20.
A 31-year-old man with AIDS was recently diagnosed with cytomegalovirus pneumonia. The patient’s current medications included zidovudine, didanosine and saquinavir. An IV therapy with ganciclovir was started. Which of the following adverse effects could be most likely predicted from the concurrent administration of ganciclovir and the antiretroviral drugs?
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Anemia and neutropenia
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Retinal detachment
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Cataract
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Sexual dysfunction
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Hyperglycemia
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Lactic acidosis
Correct Answer
A. Anemia and neutropeniaExplanation
Learning objective: describe the adverse effects of ganciclovir.
Answer: A
Ganciclovir is a drug of choice for CMV infections. The dose-limiting toxicity of both zidovudine
and ganciclovir is bone marrow suppression and therefore anemia and neutropenia can be
predicted from the concurrent administration of ganciclovir and zidovudine.
B, C) Retinal detachment and cataract are adverse effects of ganciclovir that can occur following
intravitreal administration of the drug for CMV retinitis. They do not occur when the drug is
administered IV for systemic anti-CMV therapy..
D) Sexual dysfunction is not an adverse effect of the drugs the patient has been receiving.
E) Hyperglycemia can occur after prolonged administration of protease inhibitors (i.e.
saquinavir) but does not occur with ganciclovir.
F) Lactic acidosis has been reported with the use of nucleoside reverse transcriptase inhibitors,
but it is does not occur with ganciclovir.Rate this question:
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- 21.
A 34-year-old woman reported to her physician a two-day history of genital burning pain that was worse during urination and accompanied by fever and malaise. Physical examination revealed multiple blisters and ulcerative lesions in the vaginal area. A presumptive diagnosis of herpes genitalis was made and an oral drug was prescribed. Which of the following steps of viral growth cycle was most likely inhibited by the prescribed drug?
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Attachment to the host cell
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Uncoating
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Penetration
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Transcription
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MRNA and protein synthesis
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Proteolytic cleavage
Correct Answer
A. TranscriptionExplanation
Learning objective: identify which step of viral growth cycle is inhibited by acyclovir
Answer: D
The prescribed drug was most likely acyclovir, the drug of choice for herpes genitalis. Oral
therapy speed up the healing and reduces the frequency of reactivation episodes. By inhibiting
the viral DNA polymerase the drug block DNA synthesis. Transcription is therefore inhibited.
A, B, C, E, F) (see explanation above)Rate this question:
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- 22.
A 72-year-old man was admitted to the hospital with one week history of fever, night sweats and shortness of breath. Blood exams on admission were notable for hemoglobin 10 g/dL and creatinine 3.2 mg/dL. Physical examination showed decreased lung sounds bilaterally. A viral culture from bronchoalveolar lavage was positive for HSV and a therapy with IV acyclovir was started. The patient was at increased risk of developing which of the following adverse effects as a result of this therapy?
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Hepatic cirrhosis
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Renal failure
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Hemolytic anemia
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Neutropenia
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Agranulocytosis
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Pancreatitis
Correct Answer
A. Renal failureExplanation
Learning objective: describe the adverse effects of acyclovir.
Answer: B
More than 90% of acyclovir is eliminated as such by the kidney and nephrotoxic effects can
occur with parenteral administration. These effects are more likely in the present patient
because of its decreased renal function (see creatinine levels).
A, C, D, E, F) Acyclovir has no significant toxicity on bone marrow, liver and pancreas.Rate this question:
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- 23.
A 61-year-old woman suffering from viral hepatitis B was admitted to the hospital for a follow up examination. She was found to have >105 HBV DNA copies/mL and ALT of 210 U/L (normal <20). A therapy with entecavir was prescribed. The inhibition of which of the following viral enzymes most likely mediated the therapeutic effect of the drug in the patient’s disease?
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DNA-polymerase
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Phosphotransferase
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RNA-polymerase
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HIV Protease
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Thymidine-kinase
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Neuraminidase
Correct Answer
A. DNA-polymeraseExplanation
Learning objective: explain the mechanism of action of entecavir.
Answer: A
Entecavir is a guanosine derivative that inhibits HBV DNA polymerase. The drug is more potent
than lamivudine and is highly effective in lamivudine resistant strain. Clinical resistant to
entecavir is very rare (< 1% at 4 years).
B, C, D, E, F) These enzymes are not inhibited by entecavirRate this question:
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- 24.
A 23-year-old, heroin addicted man presented to the hospital complaining of severe fatigue and scleral icterus. Physical examination showed hepatomegaly and mild ascites. Significant laboratory findings were: total bilirubin 4.4 ng/mL, ALT 380 U/L, AST 320 U/L. Serologic tests were positive for hepatitis C virus infection. Which of the following pairs of drugs would be appropriate for this patient?
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Interferon-alpha and foscarnet
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Ribavirin and saquinavir
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Interferon-alpha and ribavirin
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Saquinavir and foscarnet
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Zidovudine and ganciclovir
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Ganciclovir and foscarnet
Correct Answer
A. Interferon-alpha and ribavirinExplanation
Learning objective: outline the pharmacological therapy of hepatitis C.
Answer: C
The signs and symptoms of the patient suggest the diagnosis of viral hepatitis and the serologic
tests confirmed the presence of a HCV infection. Both HBV and HCV are transmitted
parenterally so both infections are likely in intravenous drug users. In fact the incidence of HCV
infection can be as high as 90% among these users. Interferons are the drug of choice for both
hepatitis B and C, but recently the combined therapy with interferon alpha and ribavirin has
been shown to be superior than interferon alone and the combination has been approved by
FDA for this purpose. Monotherapy with ribavirin alone is not effective.
A, B, D, E, F) All these drug combinations include at least one drug that is useless against
HCV.Rate this question:
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- 25.
A 56-year-old man suffering from viral hepatitis B had started a treatment with interferon alpha-2a, but nine month later he was still HBeAg positive. The gastroenterologist decided to stop interferon and start another drug. Which of the following drugs was most likely prescribed?
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Gancyclovir
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Lopinavir
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Raltegravir
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Nevirapine
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Didanosine
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Lamivudine
Correct Answer
A. LamivudineExplanation
Learning objective: outline the use of Interferon alpha-2a in viral hepatitis B.
Answer: F
Lamivudine has been the first nucleoside analog approved by FDA for use in patient with viral
hepatitis B. It inhibits HBV DNA polymerase and HIV reverse transcriptase by competing with
deoxycytidine triphosphate for incorporation into the viral DNA. Lamivudine is an effective agent
for patients with chronic hepatitis B. It can suppress HBV DNA to undetectable level in about
40% of patient and can normalize ALT in up to 75% of patients. Unfortunately resistance is a
problem since it can be 70% at five years of therapy.
A, B, C, D, E) these antiviral drugs are not effective against hepatitis B.Rate this question:
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.JPG "The diagram below depicts a simplified pathway of the viral growth cycle:
Which of the steps shown in the pathway is most likely inhibited by amantadine?")
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Mar 21, 2023Quiz Edited by
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Jul 06, 2012Quiz Created by
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