1. A 68-year-old woman with type 2 diabetes and chronic kidney disease presents 24 hours after the onset of fever, myalgias, and cough during a documented community influenza outbreak. A rapid influenza test is pending. Her creatinine clearance is 55 mL/min. What is the most appropriate next step?
A) Withhold antiviral therapy until the rapid influenza test result returns to confirm the diagnosis
B) Start oseltamivir now without waiting for test confirmation, because she is high-risk and within the window where early treatment most reduces complications
C) Prescribe amantadine, which is well suited to elderly diabetic patients
D) Defer treatment because antivirals are contraindicated in chronic kidney disease
E) Treat only with supportive care, since antivirals provide no benefit in patients over 65
ANSWER: B
Rationale:
She is high-risk (age, diabetes, chronic kidney disease) and presents within 48 hours during a known outbreak; early neuraminidase inhibitor therapy most reduces complications, and treatment should not be delayed waiting for confirmatory testing when clinical suspicion is high. Oseltamivir is appropriate, with dose adjustment guided by renal function.
Option A: Option A is incorrect: delaying treatment for test confirmation forfeits the early-treatment benefit in a high-risk patient and is not recommended when suspicion is high.
Option C: Option C is incorrect: amantadine is clinically obsolete for influenza because of near-universal resistance and is not an appropriate choice.
Option D: Option D is incorrect: chronic kidney disease is not a contraindication to oseltamivir; it calls for dose adjustment, not deferral.
Option E: Option E is incorrect: antivirals do provide benefit in older high-risk patients, so supportive care alone is inadequate.
2. A 30-year-old man with moderate persistent asthma presents 18 hours after the onset of influenza symptoms and asks for the most effective treatment. He has normal renal function and can swallow tablets without difficulty. Which agent is the most appropriate choice?
A) Inhaled zanamivir, because depositing drug directly in the airway is ideal in asthmatic patients
B) Amantadine, because it avoids the respiratory tract entirely
C) Aerosolized ribavirin, because it is the standard influenza treatment in asthma
D) Oral oseltamivir, because inhaled zanamivir can precipitate bronchospasm in patients with underlying airway disease, making an oral neuraminidase inhibitor preferable
E) No antiviral, because all influenza antivirals worsen asthma
ANSWER: D
Rationale:
Inhaled zanamivir can provoke bronchospasm in patients with asthma or other obstructive airway disease, so an oral neuraminidase inhibitor is preferred; oral oseltamivir is the appropriate choice for this asthmatic patient presenting early.
Option A: Option A is incorrect: the inhaled route is precisely the hazard in asthma, so zanamivir is not the ideal choice here.
Option B: Option B is incorrect: amantadine is clinically obsolete for influenza because of near-universal resistance.
Option C: Option C is incorrect: aerosolized ribavirin is not an influenza treatment and is reserved for selected severe respiratory syncytial virus disease.
Option E: Option E is incorrect: antivirals are not uniformly harmful in asthma — only the inhaled route is problematic — so withholding all antivirals is wrong.
3. A 74-year-old man with an estimated creatinine clearance of 20 mL/min is diagnosed with influenza and started on oseltamivir. Given that oseltamivir carboxylate, the active moiety, is eliminated renally, what is the most appropriate dosing approach?
A) Reduce the oseltamivir dose to account for impaired renal elimination, because the renally cleared active metabolite will otherwise accumulate
B) Use the standard 75 mg twice-daily dose without modification, because renal function does not affect oseltamivir
C) Double the dose to overcome reduced absorption in renal failure
D) Switch to amantadine, which requires no renal dose adjustment
E) Avoid oseltamivir entirely, because it is dialyzed too rapidly to be effective
ANSWER: A
Rationale:
Oseltamivir carboxylate is renally eliminated, so in significant renal impairment the dose must be reduced to prevent accumulation; dose reduction is standard below a creatinine clearance of about 30 mL/min and at this level of impairment.
Option B: Option B is incorrect: renal function clearly affects oseltamivir handling, and unmodified standard dosing risks accumulation.
Option C: Option C is incorrect: the issue is reduced elimination, not reduced absorption, so doubling the dose would worsen accumulation.
Option D: Option D is incorrect: amantadine in fact requires substantial dose reduction in renal impairment and is obsolete for influenza, so it is not a renal-sparing alternative.
Option E: Option E is incorrect: oseltamivir is effective with appropriate dose adjustment and supplemental dosing around dialysis; it is not abandoned for being dialyzed too quickly.
4. A 52-year-old woman receiving chemotherapy has had influenza A for ten days despite oseltamivir, with persistent fever and viral shedding. Genotyping of the virus reveals the H275Y neuraminidase substitution. What is the most rational change in therapy?
A) Increase the oseltamivir dose, since H275Y only slightly reduces oseltamivir binding
B) Add amantadine, since adamantanes will cover the resistant strain
C) Switch to zanamivir or intravenous peramivir, because H275Y characteristically preserves susceptibility to these agents
D) Stop antiviral therapy, because H275Y confers resistance to every available influenza drug
E) Switch to palivizumab, which neutralizes resistant influenza strains
ANSWER: C
Rationale:
H275Y confers high-level oseltamivir resistance but characteristically preserves zanamivir susceptibility, and intravenous peramivir is another option; switching to one of these is the rational response, especially in an immunocompromised patient with persistent shedding.
Option A: Option A is incorrect: H275Y produces high-level oseltamivir resistance, so dose escalation is not a reliable solution.
Option B: Option B is incorrect: adamantanes are clinically obsolete for influenza A because of near-universal M2 resistance and would not cover the strain.
Option D: Option D is incorrect: H275Y does not confer pan-resistance; zanamivir and peramivir typically remain active, so stopping all antivirals is wrong.
Option E: Option E is incorrect: palivizumab is an anti-respiratory syncytial virus monoclonal antibody with no activity against influenza.
5. A 60-year-old man is intubated in the intensive care unit with severe influenza pneumonia. He has an ileus with poor gastric emptying and high nasogastric residuals, making enteral drug absorption unreliable, and inhaled delivery is not feasible while ventilated. Which antiviral choice best addresses these constraints?
A) Oral oseltamivir via nasogastric tube at standard dosing, since absorption is adequate in critical illness
B) Inhaled zanamivir through the ventilator circuit, since it reaches the lungs directly
C) Amantadine, since the oral route avoids the need for intravenous access
D) Aerosolized ribavirin, since it is the preferred agent for influenza pneumonia
E) Intravenous peramivir, because it bypasses unreliable enteral absorption and the impracticality of inhaled delivery in a ventilated patient
ANSWER: E
Rationale:
Intravenous peramivir bypasses both the unreliable enteral absorption created by ileus and high residuals and the impracticality of inhaled delivery during mechanical ventilation, making it the appropriate neuraminidase inhibitor here.
Option A: Option A is incorrect: the scenario specifies unreliable enteral absorption, so nasogastric oseltamivir cannot be assumed to achieve adequate levels.
Option B: Option B is incorrect: inhaled zanamivir is not designed for delivery through a ventilator circuit and is not appropriate in this setting.
Option C: Option C is incorrect: amantadine is obsolete for influenza because of universal resistance, regardless of route.
Option D: Option D is incorrect: aerosolized ribavirin is not an influenza treatment; it is reserved for selected severe respiratory syncytial virus disease.
6. A 45-year-old liver transplant recipient on maintenance tacrolimus is diagnosed with mild COVID-19 and is at high risk for progression. The team considers nirmatrelvir-ritonavir. What is the most appropriate way to proceed?
A) Prescribe nirmatrelvir-ritonavir at standard dosing and continue tacrolimus unchanged, since there is no clinically relevant interaction
B) Recognize that ritonavir's CYP3A4 inhibition can markedly raise tacrolimus levels, and either coordinate tacrolimus dose modification with close level monitoring or select an alternative antiviral such as remdesivir
C) Increase the tacrolimus dose during the antiviral course to maintain immunosuppression
D) Use nirmatrelvir without ritonavir to avoid the interaction
E) Withhold all COVID-19 treatment because antivirals are contraindicated in transplant recipients
ANSWER: B
Rationale:
Ritonavir is a potent CYP3A4 inhibitor and tacrolimus is cleared by CYP3A4, so coadministration can markedly raise tacrolimus concentrations and cause toxicity; the correct approach is to manage the interaction with tacrolimus dose modification and close monitoring, or to choose an alternative antiviral such as remdesivir, which lacks this interaction.
Option A: Option A is incorrect: the interaction is clinically major, so standard dosing with unchanged tacrolimus is unsafe.
Option C: Option C is incorrect: ritonavir raises tacrolimus levels, so increasing the tacrolimus dose would compound toxicity.
Option D: Option D is incorrect: nirmatrelvir requires the ritonavir boost to reach effective concentrations, so it is not given alone.
Option E: Option E is incorrect: antivirals are not contraindicated in transplant recipients; the interaction is managed rather than a reason to withhold all treatment.
7. A healthy full-term 2-month-old is seen in early autumn as the respiratory syncytial virus season begins. The parents ask whether anything can reduce the infant's risk of severe respiratory syncytial virus disease. The infant has received no prior respiratory syncytial virus prevention. What is the most appropriate recommendation?
A) Begin monthly palivizumab injections throughout the season, as this is now first-line for healthy term infants
B) Start oral ribavirin prophylaxis for the season
C) Administer an influenza neuraminidase inhibitor as cross-protection
D) Give a single dose of nirsevimab, the long-acting monoclonal antibody recommended for infants under eight months entering their first respiratory syncytial virus season
E) Provide no prevention, because monoclonal antibodies are reserved exclusively for premature infants
ANSWER: D
Rationale:
Nirsevimab is a long-acting monoclonal antibody recommended for all infants under eight months entering their first respiratory syncytial virus season; a single dose provides season-long protection, making it the appropriate recommendation for this healthy term infant.
Option A: Option A is incorrect: palivizumab requires monthly dosing and is now reserved for specific high-risk groups rather than being first-line for healthy term infants.
Option B: Option B is incorrect: ribavirin is not used for routine respiratory syncytial virus prophylaxis.
Option C: Option C is incorrect: influenza neuraminidase inhibitors have no activity against respiratory syncytial virus and provide no cross-protection.
Option E: Option E is incorrect: nirsevimab is recommended broadly for infants entering their first season, not only for premature infants, so withholding prevention is incorrect.
8. A 9-month-old who was born at 27 weeks' gestation has chronic lung disease of prematurity requiring ongoing medical therapy and is entering the respiratory syncytial virus season. Nirsevimab is unavailable at the clinic that day. Which prophylactic strategy retains an established, guideline-supported role for this high-risk infant?
A) Monthly intramuscular palivizumab through the respiratory syncytial virus season, which remains indicated for high-risk groups such as chronic lung disease of prematurity requiring medical therapy
B) Oral oseltamivir prophylaxis through the season
C) A single dose of aerosolized ribavirin as prophylaxis
D) No prophylaxis, because palivizumab has been entirely withdrawn from use
E) An influenza vaccine, which also protects against respiratory syncytial virus
ANSWER: A
Rationale:
Palivizumab retains an established role for specific high-risk infants — including chronic lung disease of prematurity requiring ongoing medical therapy — given as monthly intramuscular injections through the season; it is the appropriate guideline-supported option for this infant when nirsevimab is not available.
Option B: Option B is incorrect: oseltamivir is an influenza drug with no respiratory syncytial virus activity.
Option C: Option C is incorrect: aerosolized ribavirin is a treatment reserved for selected severe disease, not a prophylactic strategy.
Option D: Option D is incorrect: palivizumab has not been withdrawn; it remains indicated for defined high-risk groups.
Option E: Option E is incorrect: influenza vaccine does not protect against respiratory syncytial virus.
9. A 40-year-old hematopoietic stem cell transplant recipient develops respiratory syncytial virus lower respiratory tract infection with hypoxemia and progressive infiltrates. The team considers aerosolized ribavirin. Which statement best guides its use here?
A) Ribavirin is first-line and should be given to every patient with respiratory syncytial virus, regardless of immune status
B) Ribavirin should be withheld because it has no activity against respiratory syncytial virus
C) Aerosolized ribavirin may be considered in this severely ill immunocompromised patient, where observational data suggest possible benefit, while recognizing that the drug is teratogenic and that staff of childbearing potential require respiratory protection during administration
D) Ribavirin is contraindicated in transplant recipients because immunosuppression eliminates its antiviral effect
E) Oral oseltamivir should be substituted, as it is more effective against respiratory syncytial virus
ANSWER: C
Rationale:
Aerosolized ribavirin is reserved for selected severely ill immunocompromised patients, such as hematopoietic stem cell transplant recipients with severe respiratory syncytial virus lower respiratory tract disease, where observational data suggest possible benefit; its use requires accounting for teratogenicity and the need for staff respiratory protection during administration.
Option A: Option A is incorrect: ribavirin is not first-line for all respiratory syncytial virus infection; routine infant use is not supported by strong evidence.
Option B: Option B is incorrect: ribavirin does have antiviral activity against respiratory syncytial virus through several mechanisms, so withholding it as inactive is wrong.
Option D: Option D is incorrect: ribavirin is not contraindicated in transplant recipients — that population is precisely where its reserved use is concentrated.
Option E: Option E is incorrect: oseltamivir is an influenza neuraminidase inhibitor with no activity against respiratory syncytial virus.
10. A 58-year-old man is admitted with COVID-19 pneumonia on hospital day 6 of symptoms and requires 3 liters per minute of supplemental oxygen by nasal cannula; he is not yet on high-flow oxygen or mechanical ventilation. The team asks whether remdesivir is likely to help. Which assessment is most accurate?
A) Remdesivir is unlikely to help because antivirals only benefit outpatients
B) Remdesivir should be reserved until he requires mechanical ventilation, when antiviral benefit is greatest
C) Remdesivir is contraindicated in any patient requiring supplemental oxygen
D) Remdesivir's benefit is purely anti-inflammatory, so it should replace corticosteroids rather than supplement care
E) Remdesivir is most likely to benefit him now, while he requires only low-flow oxygen and has not progressed to mechanical ventilation, because its antiviral effect is most useful earlier in the course before severe inflammation predominates
ANSWER: E
Rationale:
The clearest measurable benefit of remdesivir in hospitalized patients is in those requiring low-flow supplemental oxygen who have not progressed to mechanical ventilation; because remdesivir suppresses viral replication, its benefit concentrates earlier in the course before severe inflammation dominates, which fits this patient.
Option A: Option A is incorrect: remdesivir is used in hospitalized patients, not only outpatients.
Option B: Option B is incorrect: benefit is less clear once mechanical ventilation is required, so waiting for that stage is the opposite of the rationale.
Option C: Option C is incorrect: requiring supplemental oxygen is an indication, not a contraindication, for inpatient remdesivir.
Option D: Option D is incorrect: remdesivir is an antiviral, not an anti-inflammatory, and does not replace corticosteroids.
11. A 28-year-old woman who is 26 weeks pregnant presents with 1 day of fever, cough, and myalgias during influenza season. She has no airway disease and normal renal function. Which antiviral is the most appropriate first choice?
A) Baloxavir, because its single-dose convenience makes it ideal in pregnancy
B) Oseltamivir, because it is the preferred influenza antiviral in pregnancy, has the most accumulated safety experience, and should be started early given her symptom onset within 48 hours
C) Amantadine, because it is safe and effective against current influenza A strains in pregnancy
D) Aerosolized ribavirin, because it is well tolerated in pregnancy
E) No antiviral, because influenza antivirals are all contraindicated during pregnancy
ANSWER: B
Rationale:
Oseltamivir is the preferred influenza antiviral in pregnancy, with the most accumulated safety experience, and early initiation within 48 hours is appropriate given her recent symptom onset and the higher risk influenza poses in pregnancy.
Option A: Option A is incorrect: baloxavir is not recommended in pregnancy because of limited data, so convenience does not make it the first choice.
Option C: Option C is incorrect: amantadine is clinically obsolete for influenza because of near-universal resistance and is not an appropriate choice.
Option D: Option D is incorrect: ribavirin is teratogenic and is not an influenza treatment, so it is contraindicated in pregnancy.
Option E: Option E is incorrect: influenza antivirals are not all contraindicated in pregnancy; oseltamivir is in fact recommended, and untreated influenza carries real risk.
This Web-based pharmacology and disease-based integrated teaching site is based on reference materials that are believed reliable and consistent with standards accepted at the time of development.
Possibility of error and on-going research and development in medical sciences do not allow assurance that the information contained herein is in every respect accurate or complete.
Users should confirm the information contained herein with other sources.
This site should only be considered as a teaching aid for undergraduate and graduate biomedical education and is intended only as a teaching site.
Information contained here should not be used for patient management and should not be used as a substitute for consultation with practicing medical professionals.
Users of this website should check the product information sheet included in the package of any drug they plan to administer to be certain that the information contained in this site is accurate and that changes have not been made in the recommended dose or in the contraindications for administration.
Medical or other information thus obtained should not be used as a substitute for consultation with practicing medical or scientific or other professionals.