ATI RN
Chemotherapy drugs Questions
Question 1 of 5
A 27-year-old man presents to the urgent care clinic with multiple painful ulcers on the shaft of his penis. Some strains of the causative virus are resistant because of a mutated thymidine kinase enzyme. Which of the following antivirals may be less effective in treating this man's infection if his strain of virus has a mutated thymidine kinase?
Correct Answer: A
Rationale: In this scenario, the correct answer is A) Acyclovir. Acyclovir is a nucleoside analog antiviral drug that requires activation by viral thymidine kinase to become active against herpes simplex virus (HSV) infections. If the virus has a mutated thymidine kinase enzyme, it may not be able to activate acyclovir effectively, leading to reduced efficacy of the drug in treating the infection. Option B) Cidofovir does not require viral thymidine kinase activation for its antiviral activity, so it would still be effective against the virus with a mutated thymidine kinase. Option C) Foscarnet is a pyrophosphate analog that directly inhibits viral DNA polymerase and does not require activation by thymidine kinase. Therefore, it would remain effective against the virus with a mutated thymidine kinase. Option D) Oseltamivir is an antiviral medication used to treat influenza viruses and works by inhibiting the neuraminidase enzyme, which is not related to thymidine kinase. Therefore, the mutation in thymidine kinase would not affect the effectiveness of oseltamivir. In an educational context, understanding the mechanisms of action of antiviral drugs and how viral mutations can impact their efficacy is crucial for healthcare providers to make informed treatment decisions. This knowledge helps in selecting the most appropriate antiviral therapy tailored to the specific characteristics of the infecting virus, ultimately improving patient outcomes.
Question 2 of 5
A 3-year-old girl presents to the emergency department with a history of recurrent UTIs with costovertebral angle tenderness, high fever, and dysuria. A urine culture grows gram-negative lactose-fermenting rods. The physician suspects E. coli pyelonephritis. Ciprofloxacin is highly effective against E. coli in vitro, but the physician chooses not to use it in this case. Why would she choose not to prescribe ciprofloxacin?
Correct Answer: B
Rationale: The correct answer is B) Ciprofloxacin is contraindicated in patients younger than 18 years old. This is because ciprofloxacin belongs to a class of antibiotics called fluoroquinolones, which are associated with potential serious side effects like tendon rupture and joint problems in pediatric patients. The use of ciprofloxacin in children under 18 years old is generally restricted to specific situations where no other suitable alternative exists due to these safety concerns. Option A is incorrect because ciprofloxacin is actually bactericidal, meaning it kills bacteria rather than just inhibiting their growth (bacteriostatic). Option C is incorrect as ciprofloxacin is effective against E. coli both in vitro (in laboratory settings) and in vivo (in the body), but its use is limited in pediatric populations due to safety reasons. Option D is incorrect because although ciprofloxacin can have side effects like any medication, nephrotoxicity (toxic to the kidneys) is not a primary concern associated with this drug. Educationally, it is crucial for healthcare providers to be aware of age-specific contraindications and safety considerations when prescribing medications, especially antibiotics, to pediatric patients. Understanding the rationale behind drug choices based on patient age, safety profiles, and efficacy helps in providing optimal care while minimizing potential risks.
Question 3 of 5
A 21-year-old man presents to the ambulatory care clinic with an erythematous, swollen, painful left elbow. History is significant for untreated impetigo on his left forearm. A joint aspirate reveals gram-positive cocci in clusters. The physician begins empiric treatment with vancomycin while the organism is cultured. It is found to be methicillin susceptible. Methicillin is not widely used, but which of the following is an equivalent drug that could be used to treat this man's infection?
Correct Answer: C
Rationale: The correct answer is C) Oxacillin. Oxacillin is an equivalent drug to methicillin because both belong to the class of penicillinase-resistant penicillins. These drugs are effective against staphylococci, including methicillin-susceptible strains. In this case, the patient's infection is caused by gram-positive cocci, and using an agent like oxacillin ensures effective treatment. A) Amoxicillin and B) Ampicillin are aminopenicillins, which are not effective against methicillin-resistant staphylococci. D) Penicillin G is a natural penicillin and lacks the resistance profile needed to combat methicillin-susceptible strains. In an educational context, understanding the differences between various classes of antibiotics is crucial for healthcare professionals to make informed decisions when treating infections. Knowing the appropriate drug choices based on microbial susceptibility patterns is essential to ensure effective therapy and prevent the development of antibiotic resistance.
Question 4 of 5
A 25-year-old man presents to the emergency department with severe abdominal pain, rigors, and a temperature of 39°C. For the past 2 days, he has suffered from right lower quadrant pain and only came to the hospital when it suddenly worsened. The physician suspects ruptured appendicitis and administers imipenem with cilastatin. Cilastatin blocks which of the following enzymes to increase imipenem's efficacy?
Correct Answer: C
Rationale: In this scenario, the correct answer is C) Dehydropeptidase. Imipenem is a broad-spectrum antibiotic that is often administered with cilastatin, a dehydropeptidase inhibitor. Dehydropeptidase is an enzyme in the kidney that breaks down imipenem, reducing its efficacy. By blocking dehydropeptidase with cilastatin, the levels of imipenem in the body are increased, enhancing its effectiveness in treating infections. Option A) Bacterial efflux pump is incorrect because it refers to a mechanism used by bacteria to remove antibiotics from the cell, which is not relevant in this context. Option B) CYP3A4 is incorrect because it is a liver enzyme responsible for metabolizing drugs, not degrading imipenem like dehydropeptidase. Option D) Organic anion transporter is incorrect as it is involved in the transport of certain compounds across cell membranes and not related to the metabolism of imipenem. Understanding the interaction between imipenem and cilastatin is crucial in clinical practice to ensure the optimal therapeutic effect of these chemotherapy drugs. Knowing how cilastatin enhances imipenem's efficacy by inhibiting dehydropeptidase can help healthcare professionals make informed decisions when treating patients with severe infections.
Question 5 of 5
A 21-year-old woman college student complains of a skin lesion near her knee on the inside of her thigh. She recently returned from a trip to Africa where she played a handmade goatskin drum. The lesion is painless with a black center. The physician suspects cutaneous anthrax and prescribes oral ciprofloxacin. Which of the following should this patient avoid taking with ciprofloxacin?
Correct Answer: C
Rationale: In this scenario, the correct answer is C) Milk. Ciprofloxacin belongs to a class of antibiotics called fluoroquinolones, which can chelate (bind to) divalent and trivalent cations like calcium, magnesium, and aluminum. Milk and dairy products contain calcium, which can interfere with the absorption of ciprofloxacin, reducing its effectiveness. Therefore, it is recommended to avoid taking ciprofloxacin with milk or other dairy products. Alcohol (option A) does not interact significantly with ciprofloxacin. Grapefruit juice (option B) can interact with certain medications by affecting their metabolism in the liver, but it does not have a significant interaction with ciprofloxacin. St. John's wort (option D) is an herbal supplement that can induce liver enzymes and potentially reduce the effectiveness of certain medications, but it does not have a specific interaction with ciprofloxacin. In an educational context, understanding drug interactions is crucial for healthcare professionals to ensure the safe and effective use of medications. Teaching students about specific drug interactions, like the one between ciprofloxacin and dairy products, helps them make informed decisions when prescribing medications and advising patients on proper medication use. It also highlights the importance of patient education regarding drug-food interactions to optimize treatment outcomes.