Pharmacology Quiz: Chemotherapy Adverse Effects
20 questions · exam conditions
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Chemotherapy Adverse EffectsQuestion 1 of 20

A 58-year-old male with metastatic non-small cell lung cancer is scheduled to receive his first cycle of cisplatin (100 mg/m²) and pemetrexed. His baseline serum creatinine is 1.1 mg/dL and eGFR is 65 mL/min/1.73m². Which of the following pre-treatment regimens is most critical to mitigate a well-known, dose-limiting toxicity of this regimen?

Administration of dexrazoxane prior to cisplatin infusion to prevent cardiotoxicity.
Pre-medication with atropine to prevent acute cholinergic symptoms and diarrhea.
Vigorous intravenous hydration with 1-2 liters of normal saline containing magnesium and potassium.
Prophylactic administration of mesna to prevent hemorrhagic cystitis.
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Pharmacology Quiz

Pharmacology Quiz: Chemotherapy Adverse Effects

Practice Chemotherapy Adverse Effects in Pharmacology with focused quiz questions that help you check what you know, review explanations, and build confidence with test-style prompts.

What this quiz covers

This quiz focuses on Chemotherapy Adverse Effects, giving you a quick way to practice the rules, question types, and explanations that matter most for Pharmacology.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

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Question 1

A 58-year-old male with metastatic non-small cell lung cancer is scheduled to receive his first cycle of cisplatin (100 mg/m²) and pemetrexed. His baseline serum creatinine is 1.1 mg/dL and eGFR is 65 mL/min/1.73m². Which of the following pre-treatment regimens is most critical to mitigate a well-known, dose-limiting toxicity of this regimen?

  1. Administration of dexrazoxane prior to cisplatin infusion to prevent cardiotoxicity.
  2. Pre-medication with atropine to prevent acute cholinergic symptoms and diarrhea.
  3. Vigorous intravenous hydration with 1-2 liters of normal saline containing magnesium and potassium. (correct answer)
  4. Prophylactic administration of mesna to prevent hemorrhagic cystitis.
Explanation: Cisplatin is highly nephrotoxic, a dose-limiting toxicity. The primary strategy to prevent cisplatin-induced acute kidney injury is aggressive pre- and post-hydration with chloride-containing fluids (e.g., normal saline), which promotes a chloride diuresis and reduces the concentration and renal transit time of platinum species. Electrolyte supplementation with magnesium and potassium is also crucial as cisplatin causes significant renal wasting of these electrolytes. A is incorrect; dexrazoxane is used to prevent anthracycline-induced cardiotoxicity or treat its extravasation. B is incorrect; atropine is used for early-onset diarrhea associated with irinotecan. D is incorrect; mesna is a uroprotectant used with ifosfamide and high-dose cyclophosphamide to prevent hemorrhagic cystitis by binding acrolein.

Question 2

A 62-year-old patient receiving chemotherapy for acute myeloid leukemia presents to the emergency department on day 10 of her cycle with a temperature of 38.5°C and chills. Her absolute neutrophil count (ANC) is 150/µL. After blood cultures are drawn, what is the most critical immediate management step?

  1. Administer a dose of pegfilgrastim to stimulate neutrophil recovery.
  2. Administer intravenous fluids and acetaminophen and observe for 24 hours.
  3. Obtain a chest X-ray and urinalysis to identify the source of infection.
  4. Initiate empiric intravenous administration of a broad-spectrum antibiotic. (correct answer)
Explanation: When you encounter a patient with fever and severe neutropenia (ANC < 500/µL), you're dealing with a medical emergency called febrile neutropenia. These patients have virtually no immune defense against bacterial infections, which can rapidly progress to sepsis and death within hours. The correct answer is D because empiric broad-spectrum antibiotics must be started immediately—ideally within one hour of presentation. Common choices include piperacillin-tazobactam, cefepime, or meropenem. The goal is to cover gram-positive and gram-negative bacteria before cultures identify the specific pathogen, since waiting 24-48 hours for culture results could be fatal. Answer A is wrong because pegfilgrastim (a granulocyte colony-stimulating factor) takes days to weeks to increase neutrophil counts—too slow for an acute infection. Answer B is dangerous because observation delays life-saving treatment; acetaminophen and fluids are supportive but inadequate as primary therapy. Answer C represents a common trap—while identifying infection sources is important, diagnostic workups should never delay antibiotic administration in febrile neutropenia. These tests can be done simultaneously or after antibiotics are started. Remember the "golden hour" principle for febrile neutropenia: antibiotics within 60 minutes of presentation significantly improve survival. On pharmacology exams, when you see fever + severe neutropenia, immediately think "empiric antibiotics first, everything else second." This is one of the few true emergencies in oncology where minutes matter for patient survival.

Question 3

A 22-year-old male with osteosarcoma receives high-dose methotrexate (12 g/m²). His protocol requires leucovorin rescue to begin 24 hours post-infusion. At 48 hours, his methotrexate level is 8 µmol/L (protocol goal < 0.1 µmol/L), and his serum creatinine has doubled. Which statement best describes the role of leucovorin in this situation and the necessary course of action?

  1. Leucovorin is a competitive inhibitor of methotrexate and should be discontinued due to renal toxicity.
  2. Leucovorin reverses the anti-tumor effect of methotrexate; glucarpidase should be administered to maintain efficacy.
  3. Leucovorin directly enhances the renal clearance of methotrexate; hydration should be the primary focus.
  4. Leucovorin provides a reduced folate source, bypassing the enzymatic block by methotrexate in healthy cells; the dose should be increased. (correct answer)
Explanation: When you encounter high-dose methotrexate toxicity questions, focus on understanding leucovorin's mechanism and the clinical scenario's urgency signals. Methotrexate blocks dihydrofolate reductase, preventing the conversion of dihydrofolate to tetrahydrofolate, which cells need for DNA synthesis. This affects both cancer cells and rapidly dividing normal cells. Leucovorin (folinic acid) is already in the reduced tetrahydrofolate form, so it bypasses the blocked enzyme and rescues normal cells while cancer cells remain trapped by higher methotrexate concentrations. In this case, the dramatically elevated methotrexate level (8 µmol/L vs. goal <0.1 µmol/L) combined with doubled creatinine indicates severe toxicity with impaired renal clearance. The correct approach is D: leucovorin provides reduced folate to bypass methotrexate's enzymatic block, and the dose must be increased to match the higher-than-expected methotrexate levels. A is wrong because leucovorin isn't a competitive inhibitor—it's a folate cofactor replacement. Discontinuing it would worsen toxicity. B misunderstands leucovorin's selectivity; it preferentially rescues normal cells, and glucarpidase is reserved for life-threatening situations. C incorrectly attributes renal clearance enhancement to leucovorin—while hydration helps, leucovorin's role is cellular rescue, not elimination. Study tip: Remember that leucovorin dosing must be adjusted based on methotrexate levels and duration of exposure. Higher or prolonged methotrexate levels require proportionally higher leucovorin doses until methotrexate clears to safe levels.

Question 4

A 72-year-old patient with myelodysplastic syndrome is receiving a hypomethylating agent. His baseline platelet count is 60,000/µL. After one cycle, his platelet count drops to 8,000/µL. He reports no bleeding, bruising, or petechiae. Which of the following is the most appropriate next step?

  1. Administer prophylactic platelet transfusion to maintain count >10,000/µL. (correct answer)
  2. Initiate a thrombopoietin receptor agonist such as romiplostim.
  3. Continue to monitor counts and provide supportive care only if bleeding occurs.
  4. Permanently discontinue the hypomethylating agent due to severe hematologic toxicity.
Explanation: When managing hematologic toxicity from hypomethylating agents in myelodysplastic syndrome, you need to balance treatment efficacy with bleeding risk. These agents commonly cause cytopenias as they work, but severe thrombocytopenia requires immediate intervention to prevent life-threatening hemorrhage. A platelet count of 8,000/µL represents severe thrombocytopenia with high bleeding risk, even without current symptoms. The standard threshold for prophylactic platelet transfusion is 10,000/µL in stable patients, as spontaneous bleeding (particularly intracranial hemorrhage) becomes significantly more likely below this level. Answer A is correct because maintaining platelets above 10,000/µL through transfusion provides essential protection while allowing continued treatment. Answer B is wrong because thrombopoietin receptor agonists like romiplostim take weeks to show effect and aren't first-line for acute severe thrombocytopenia in this setting. Answer C is dangerously inappropriate—waiting for bleeding to occur at 8,000/µL risks catastrophic hemorrhage, particularly intracranial bleeding that could be fatal. Answer D represents premature discontinuation; hypomethylating agents are often the best treatment option for MDS, and transient cytopenias are expected and manageable. Remember that platelet transfusion thresholds are higher in actively bleeding patients (50,000/µL) versus stable patients (10,000/µL). For pharmacology exams, know that supportive care measures like transfusions often allow continuation of effective but toxic therapies, rather than abandoning treatment entirely.

Question 5

A 40-year-old patient with sarcoma is treated with a high-dose ifosfamide regimen. On the third day of the infusion, he becomes increasingly lethargic, confused, and experiences visual hallucinations. An EEG shows diffuse slowing. This encephalopathy is suspected to be drug-induced. Accumulation of which metabolite is responsible, and what is the indicated antidote?

  1. Chloroacetaldehyde; treated with intravenous methylene blue. (correct answer)
  2. Acrolein; treated with aggressive hydration and mesna.
  3. Trichloroacetic acid; treated with N-acetylcysteine.
  4. Methylmalonic acid; treated with vitamin B12 supplementation.
Explanation: When you encounter neurological toxicity with chemotherapy agents, think systematically about which drugs have characteristic neurotoxic metabolites and their specific antidotes. Ifosfamide, an alkylating agent related to cyclophosphamide, undergoes hepatic metabolism that can produce several metabolites. The key neurotoxic metabolite is chloroacetaldehyde, which crosses the blood-brain barrier and causes encephalopathy characterized by confusion, lethargy, and hallucinations—exactly what this patient is experiencing. The EEG showing diffuse slowing confirms this diagnosis. Methylene blue is the specific antidote because it inhibits the formation of chloroacetaldehyde and enhances its clearance, making option A correct. Option B confuses ifosfamide toxicity with acrolein, which is actually the metabolite responsible for hemorrhagic cystitis (not encephalopathy) from both ifosfamide and cyclophosphamide. Mesna prevents this urological toxicity but doesn't treat CNS effects. Option C incorrectly identifies trichloroacetic acid as the culprit metabolite and suggests N-acetylcysteine, which is used for acetaminophen overdose, not ifosfamide neurotoxicity. Option D mentions methylmalonic acid and vitamin B12, which are relevant to vitamin B12 deficiency-induced neurological problems, not chemotherapy-induced encephalopathy. Study tip: For chemotherapy toxicities, memorize the classic triad: ifosfamide causes encephalopathy (chloroacetaldehyde → methylene blue), hemorrhagic cystitis (acrolein → mesna), and nephrotoxicity. This pattern frequently appears on pharmacology exams testing antidote knowledge.

Question 6

A 62-year-old patient receiving chemotherapy for acute myeloid leukemia presents to the emergency department on day 10 of her cycle with a temperature of 38.5°C and chills. Her absolute neutrophil count (ANC) is 150/µL. After blood cultures are drawn, what is the most critical immediate management step?

  1. Administer a dose of pegfilgrastim to stimulate neutrophil recovery.
  2. Administer intravenous fluids and acetaminophen and observe for 24 hours.
  3. Obtain a chest X-ray and urinalysis to identify the source of infection.
  4. Initiate empiric intravenous administration of a broad-spectrum antibiotic. (correct answer)
Explanation: When you encounter a patient with fever and severe neutropenia (ANC < 500/µL), you're dealing with a medical emergency called febrile neutropenia. These patients have virtually no immune defense against bacterial infections, which can rapidly progress to sepsis and death within hours. The correct answer is D because empiric broad-spectrum antibiotics must be started immediately—ideally within one hour of presentation. Common choices include piperacillin-tazobactam, cefepime, or meropenem. The goal is to cover gram-positive and gram-negative bacteria before cultures identify the specific pathogen, since waiting 24-48 hours for culture results could be fatal. Answer A is wrong because pegfilgrastim (a granulocyte colony-stimulating factor) takes days to weeks to increase neutrophil counts—too slow for an acute infection. Answer B is dangerous because observation delays life-saving treatment; acetaminophen and fluids are supportive but inadequate as primary therapy. Answer C represents a common trap—while identifying infection sources is important, diagnostic workups should never delay antibiotic administration in febrile neutropenia. These tests can be done simultaneously or after antibiotics are started. Remember the "golden hour" principle for febrile neutropenia: antibiotics within 60 minutes of presentation significantly improve survival. On pharmacology exams, when you see fever + severe neutropenia, immediately think "empiric antibiotics first, everything else second." This is one of the few true emergencies in oncology where minutes matter for patient survival.

Question 7

A 65-year-old male with metastatic prostate cancer is receiving palliative chemotherapy and develops anemia with a hemoglobin of 8.5 g/dL. He is symptomatic with fatigue and shortness of breath. The physician considers starting an erythropoiesis-stimulating agent (ESA). Which of the following is an absolute prerequisite before initiating ESA therapy in this patient, based on safety and efficacy guidelines?

  1. Confirming that the chemotherapy regimen is not intended to be curative. (correct answer)
  2. Documenting a serum ferritin level > 100 ng/mL and transferrin saturation > 20%.
  3. Performing a bone marrow biopsy to rule out erythroid aplasia.
  4. Obtaining informed consent discussing the increased risk of venous thromboembolism.
Explanation: According to FDA guidelines and REMS programs for ESAs, a critical safety requirement is that they should only be used to treat chemotherapy-induced anemia in patients with non-myeloid malignancies where the chemotherapy is palliative (not curative). This is due to studies showing decreased survival and increased tumor progression when ESAs are used in patients receiving treatment with curative intent. While assessing iron stores (B) is crucial for efficacy and obtaining informed consent (D) is best practice, the absolute contraindication related to treatment intent (A) is the most critical prerequisite that must be met before even considering the therapy. C is incorrect; a biopsy would only be needed if pure red cell aplasia, a rare side effect, was suspected.

Question 8

A nurse is administering a doxorubicin infusion via a peripheral IV. The patient complains of burning pain at the site. The nurse stops the infusion and notes swelling and redness with no blood return on aspiration. Which set of actions is most appropriate for managing this suspected extravasation?

  1. Remove the IV catheter, apply a warm compress, and administer intravenous hydrocortisone.
  2. Leave the IV in place, aspirate any residual drug, apply a warm compress, and administer hyaluronidase locally.
  3. Remove the IV catheter, elevate the limb, apply a dry sterile dressing, and monitor for 24 hours.
  4. Leave the IV in place, aspirate any residual drug, apply a cold compress, and administer intravenous dexrazoxane. (correct answer)
Explanation: Doxorubicin is a vesicant, and extravasation is a medical emergency that can cause severe tissue necrosis. The correct procedure is to stop the infusion, leave the catheter in place to attempt aspiration of residual drug, and then remove it. For anthracyclines, cold compresses should be applied to cause vasoconstriction and localize the drug. Warm compresses (A, B) are contraindicated as they cause vasodilation and enhance drug distribution. The specific FDA-approved antidote for anthracycline extravasation is dexrazoxane (Totect®), which should be administered systemically. Hyaluronidase (B) is an antidote for vinca alkaloid extravasation. Simple observation (C) is insufficient for a known vesicant.

Question 9

A 68-year-old female with metastatic breast cancer is being treated with oral capecitabine. She presents with Grade 2 palmar-plantar erythrodysesthesia (hand-foot syndrome), characterized by painful erythema and swelling of her palms and soles that limits her instrumental activities of daily living. Which of the following is the most appropriate management strategy?

  1. Immediately and permanently discontinue capecitabine and switch to an alternative agent.
  2. Continue capecitabine at the current dose and initiate high-dose pyridoxine (vitamin B6).
  3. Interrupt capecitabine therapy until symptoms improve to Grade 1, then restart at a reduced dose. (correct answer)
  4. Administer a single dose of dexrazoxane to chelate iron and reduce free radical damage.
Explanation: The standard management for Grade 2 or higher hand-foot syndrome (HFS) is to interrupt the causative agent (capecitabine) until the toxicity resolves to Grade 0 or 1. Therapy can then be re-initiated at a lower dose to prevent recurrence. A is too aggressive; permanent discontinuation is usually reserved for life-threatening (Grade 4) toxicities or recurrent severe HFS despite dose reduction. B is inappropriate; continuing the full dose will worsen the toxicity. While pyridoxine has been studied for HFS, its efficacy is unproven, and it should not be used in place of dose modification. D is incorrect; dexrazoxane is used for anthracycline cardiotoxicity/extravasation, not HFS.

Question 10

A patient receiving high-dose cyclophosphamide as part of a bone marrow transplant conditioning regimen develops gross hematuria and suprapubic pain. Urinalysis confirms microscopic and macroscopic hematuria. Co-administration of which agent could have most effectively prevented this complication by detoxifying the responsible metabolite?

  1. Allopurinol, by inhibiting xanthine oxidase and reducing uric acid production.
  2. Amifostine, by scavenging free radicals generated by the alkylating agent.
  3. Leucovorin, by competing with the cytotoxic agent for transport into urothelial cells.
  4. Mesna, by forming a non-toxic conjugate with acrolein in the urinary bladder. (correct answer)
Explanation: The patient's symptoms are classic for hemorrhagic cystitis, a known toxicity of cyclophosphamide and ifosfamide. This is caused by the accumulation of a toxic metabolite, acrolein, in the bladder. Mesna (sodium 2-mercaptoethane sulfonate) is a uroprotectant that concentrates in the bladder and its sulfhydryl group binds to and inactivates acrolein, preventing urothelial damage. A is incorrect; allopurinol is used to prevent tumor lysis syndrome. B is incorrect; amifostine is a cytoprotectant used to reduce nephrotoxicity with cisplatin and xerostomia with radiation, but not hemorrhagic cystitis. C is incorrect; leucovorin is a reduced folate used as a rescue agent for high-dose methotrexate toxicity.

Question 11

A 65-year-old female patient with diffuse large B-cell lymphoma is being treated with the R-CHOP regimen (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone). After her third cycle, she reports new-onset tingling in her fingers and toes and difficulty buttoning her shirt. Her complete blood count is unremarkable. Which medication is most likely responsible for her symptoms, and what is the most appropriate initial management step?

  1. Doxorubicin; schedule an echocardiogram to assess for cardiotoxicity.
  2. Vincristine; hold the next dose and consider a dose reduction for subsequent cycles. (correct answer)
  3. Cyclophosphamide; administer mesna with the next infusion to prevent further neurotoxicity.
  4. Rituximab; premedicate with diphenhydramine and acetaminophen for infusion-related reactions.
Explanation: The patient is experiencing classic symptoms of peripheral neuropathy (sensory and fine motor deficits), which is the dose-limiting toxicity of vincristine. The most appropriate initial management for grade 2 neuropathy is to hold the offending agent and consider a dose reduction upon resolution to a lower grade. A is incorrect because doxorubicin's primary toxicity is cardiotoxicity, not peripheral neuropathy. C is incorrect as cyclophosphamide's dose-limiting toxicities are myelosuppression and hemorrhagic cystitis; mesna is a uroprotectant, not a neuroprotectant. D is incorrect as rituximab causes infusion-related reactions, not a cumulative peripheral neuropathy.

Question 12

A patient is to receive a chemotherapy regimen with a >20% risk of febrile neutropenia. The decision is made to use primary prophylaxis with pegfilgrastim. The chemotherapy is administered on Day 1 of a 21-day cycle. According to standard guidelines, what is the most appropriate timing for the administration of the single dose of pegfilgrastim?

  1. On Day 1, at least 6 hours prior to the start of chemotherapy.
  2. On Day 1, immediately following the completion of chemotherapy.
  3. On Day 2, approximately 24 hours after completion of chemotherapy. (correct answer)
  4. On Day 10, at the expected time of the neutrophil nadir.
Explanation: Pegfilgrastim, a long-acting G-CSF, should be administered approximately 24 hours after the completion of cytotoxic chemotherapy. Administering it on the same day as chemotherapy (B) is contraindicated because it can increase myelosuppression by stimulating myeloid progenitor cells to divide, making them more susceptible to the cytotoxic effects of the chemotherapy. Administering it before chemo (A) is also incorrect. Administering it at the nadir (D) is too late for prophylaxis; the goal is to shorten the duration of severe neutropenia and prevent the nadir from being as deep, which requires administration before the nadir occurs.

Question 13

A patient receiving high-dose cyclophosphamide as part of a bone marrow transplant conditioning regimen develops gross hematuria and suprapubic pain. Urinalysis confirms microscopic and macroscopic hematuria. Co-administration of which agent could have most effectively prevented this complication by detoxifying the responsible metabolite?

  1. Allopurinol, by inhibiting xanthine oxidase and reducing uric acid production.
  2. Amifostine, by scavenging free radicals generated by the alkylating agent.
  3. Leucovorin, by competing with the cytotoxic agent for transport into urothelial cells.
  4. Mesna, by forming a non-toxic conjugate with acrolein in the urinary bladder. (correct answer)
Explanation: The patient's symptoms are classic for hemorrhagic cystitis, a known toxicity of cyclophosphamide and ifosfamide. This is caused by the accumulation of a toxic metabolite, acrolein, in the bladder. Mesna (sodium 2-mercaptoethane sulfonate) is a uroprotectant that concentrates in the bladder and its sulfhydryl group binds to and inactivates acrolein, preventing urothelial damage. A is incorrect; allopurinol is used to prevent tumor lysis syndrome. B is incorrect; amifostine is a cytoprotectant used to reduce nephrotoxicity with cisplatin and xerostomia with radiation, but not hemorrhagic cystitis. C is incorrect; leucovorin is a reduced folate used as a rescue agent for high-dose methotrexate toxicity.

Question 14

A 48-year-old patient is scheduled to receive their first cycle of AC chemotherapy (doxorubicin and cyclophosphamide) for breast cancer. This regimen is classified as having high emetic risk. Which of the following prophylactic antiemetic regimens provides the most appropriate coverage for both acute and delayed chemotherapy-induced nausea and vomiting (CINV)?

  1. Ondansetron on day 1, followed by prochlorperazine as needed on days 2-4.
  2. Aprepitant, ondansetron, and dexamethasone on day 1, followed by dexamethasone on days 2-4. (correct answer)
  3. Metoclopramide and diphenhydramine on day 1, followed by lorazepam as needed.
  4. Dexamethasone on day 1 only, with scopolamine patch for delayed nausea.
Explanation: For high emetic risk chemotherapy, guidelines recommend a three- or four-drug combination for prophylaxis. The core three-drug regimen includes an NK1 receptor antagonist (e.g., aprepitant), a 5-HT3 receptor antagonist (e.g., ondansetron), and a corticosteroid (dexamethasone). This combination provides optimal coverage for acute CINV (day 1). Continuing dexamethasone (and sometimes the NK1 antagonist, depending on the agent) on subsequent days is crucial for preventing delayed CINV. A is inadequate as it lacks an NK1 antagonist and sufficient delayed coverage. C represents an older, less effective regimen. D is completely inadequate for high emetic risk chemotherapy.

Question 15

A patient with small cell lung cancer receives a cisplatin-based regimen. He receives appropriate prophylaxis and has no nausea on day 1. On day 3 post-chemotherapy, he calls the clinic reporting debilitating nausea and two episodes of vomiting. Which neuro-receptor pathway is most likely mediating his delayed symptoms, and which class of medication is particularly effective in managing this phase?

  1. Dopamine D2 pathway; a phenothiazine like prochlorperazine.
  2. Serotonin 5-HT3 pathway; a 5-HT3 antagonist like ondansetron.
  3. Substance P/Neurokinin-1 (NK1) pathway; an NK1 antagonist like aprepitant. (correct answer)
  4. Histamine H1 pathway; an antihistamine like diphenhydramine.
Explanation: Delayed chemotherapy-induced nausea and vomiting (CINV), which typically occurs 24 hours to 5 days after chemotherapy, is primarily mediated by the release of Substance P in the brain, which acts on neurokinin-1 (NK1) receptors. Cisplatin is highly associated with delayed CINV. While other pathways contribute, the NK1 pathway is the most significant target for delayed CINV. Therefore, NK1 antagonists (e.g., aprepitant, fosaprepitant) are a cornerstone of preventing and managing delayed CINV from highly emetogenic chemotherapy. While 5-HT3 antagonists (B) are critical for acute CINV, their role in delayed CINV is less prominent. Dopamine (A) and histamine (D) pathways are less significant drivers of delayed CINV from cisplatin.

Question 16

A patient with high-tumor-burden Burkitt lymphoma begins intensive chemotherapy. Within 24 hours, his labs show: K+ 6.2 mEq/L, PO4 7.8 mg/dL, Ca2+ 7.1 mg/dL, and uric acid 18 mg/dL. He is oliguric. Which agent is most appropriate to rapidly lower his serum uric acid and prevent further renal injury from crystal deposition?

  1. Allopurinol, to block the conversion of hypoxanthine and xanthine to uric acid.
  2. Rasburicase, to catalyze the oxidation of existing uric acid to the more soluble allantoin. (correct answer)
  3. Sevelamer, to bind dietary phosphate in the GI tract and lower serum phosphate levels.
  4. Sodium bicarbonate infusion, to alkalinize the urine and increase uric acid solubility.
Explanation: This patient has severe, established laboratory and clinical tumor lysis syndrome (TLS). He has hyperuricemia, hyperkalemia, hyperphosphatemia, and secondary hypocalcemia with acute kidney injury. In the setting of established, severe hyperuricemia (>8-10 mg/dL), rasburicase is the drug of choice. It is a recombinant urate oxidase enzyme that rapidly converts existing uric acid into allantoin, which is much more soluble and readily excreted. Allopurinol (A) is a xanthine oxidase inhibitor used for prophylaxis or in mild cases; it prevents new uric acid formation but does not reduce existing levels and can even increase xanthine levels, which can also precipitate in tubules. Sevelamer (C) is a phosphate binder, which is part of TLS management but does not address the critical hyperuricemia. Urine alkalinization (D) is no longer routinely recommended due to the risk of xanthine and calcium phosphate precipitation.

Question 17

A 22-year-old male with osteosarcoma receives high-dose methotrexate (12 g/m²). His protocol requires leucovorin rescue to begin 24 hours post-infusion. At 48 hours, his methotrexate level is 8 µmol/L (protocol goal < 0.1 µmol/L), and his serum creatinine has doubled. Which statement best describes the role of leucovorin in this situation and the necessary course of action?

  1. Leucovorin is a competitive inhibitor of methotrexate and should be discontinued due to renal toxicity.
  2. Leucovorin reverses the anti-tumor effect of methotrexate; glucarpidase should be administered to maintain efficacy.
  3. Leucovorin directly enhances the renal clearance of methotrexate; hydration should be the primary focus.
  4. Leucovorin provides a reduced folate source, bypassing the enzymatic block by methotrexate in healthy cells; the dose should be increased. (correct answer)
Explanation: When you encounter high-dose methotrexate toxicity questions, focus on understanding leucovorin's mechanism and the clinical scenario's urgency signals. Methotrexate blocks dihydrofolate reductase, preventing the conversion of dihydrofolate to tetrahydrofolate, which cells need for DNA synthesis. This affects both cancer cells and rapidly dividing normal cells. Leucovorin (folinic acid) is already in the reduced tetrahydrofolate form, so it bypasses the blocked enzyme and rescues normal cells while cancer cells remain trapped by higher methotrexate concentrations. In this case, the dramatically elevated methotrexate level (8 µmol/L vs. goal <0.1 µmol/L) combined with doubled creatinine indicates severe toxicity with impaired renal clearance. The correct approach is D: leucovorin provides reduced folate to bypass methotrexate's enzymatic block, and the dose must be increased to match the higher-than-expected methotrexate levels. A is wrong because leucovorin isn't a competitive inhibitor—it's a folate cofactor replacement. Discontinuing it would worsen toxicity. B misunderstands leucovorin's selectivity; it preferentially rescues normal cells, and glucarpidase is reserved for life-threatening situations. C incorrectly attributes renal clearance enhancement to leucovorin—while hydration helps, leucovorin's role is cellular rescue, not elimination. Study tip: Remember that leucovorin dosing must be adjusted based on methotrexate levels and duration of exposure. Higher or prolonged methotrexate levels require proportionally higher leucovorin doses until methotrexate clears to safe levels.

Question 18

A patient receiving FOLFOX for colon cancer reports that within hours of his last oxaliplatin infusion, he experienced intense jaw pain and throat tightness when trying to drink a glass of cold water. The symptoms resolved within a day. What is the most appropriate counseling for this patient regarding future cycles?

  1. This is an early sign of a severe allergic reaction, and oxaliplatin should be discontinued.
  2. These are symptoms of cumulative, permanent neurotoxicity that will require a dose reduction.
  3. This is an acute, cold-induced neuropathy; avoid cold temperatures, foods, and drinks for 3-5 days post-infusion. (correct answer)
  4. This is related to electrolyte imbalance; increase intake of potassium and magnesium-rich foods.
Explanation: Oxaliplatin causes a unique acute, transient peripheral sensory neuropathy that is exacerbated by exposure to cold. It is thought to be caused by the drug's effect on voltage-gated sodium channels in neurons. The symptoms described (pharyngolaryngeal dysesthesia, jaw pain) are classic manifestations. This is distinct from the chronic, cumulative neuropathy that can also occur. The primary management is patient education and counseling to avoid cold stimuli for several days following each infusion. A is incorrect; while HSRs can occur, these specific symptoms are classic for the acute neuropathy. B is incorrect because this describes the acute, transient form, not the cumulative, chronic form. D is incorrect as the mechanism is not electrolyte-based.

Question 19

A 72-year-old patient with myelodysplastic syndrome is receiving a hypomethylating agent. His baseline platelet count is 60,000/µL. After one cycle, his platelet count drops to 8,000/µL. He reports no bleeding, bruising, or petechiae. Which of the following is the most appropriate next step?

  1. Administer prophylactic platelet transfusion to maintain count >10,000/µL. (correct answer)
  2. Initiate a thrombopoietin receptor agonist such as romiplostim.
  3. Continue to monitor counts and provide supportive care only if bleeding occurs.
  4. Permanently discontinue the hypomethylating agent due to severe hematologic toxicity.
Explanation: When managing hematologic toxicity from hypomethylating agents in myelodysplastic syndrome, you need to balance treatment efficacy with bleeding risk. These agents commonly cause cytopenias as they work, but severe thrombocytopenia requires immediate intervention to prevent life-threatening hemorrhage. A platelet count of 8,000/µL represents severe thrombocytopenia with high bleeding risk, even without current symptoms. The standard threshold for prophylactic platelet transfusion is 10,000/µL in stable patients, as spontaneous bleeding (particularly intracranial hemorrhage) becomes significantly more likely below this level. Answer A is correct because maintaining platelets above 10,000/µL through transfusion provides essential protection while allowing continued treatment. Answer B is wrong because thrombopoietin receptor agonists like romiplostim take weeks to show effect and aren't first-line for acute severe thrombocytopenia in this setting. Answer C is dangerously inappropriate—waiting for bleeding to occur at 8,000/µL risks catastrophic hemorrhage, particularly intracranial bleeding that could be fatal. Answer D represents premature discontinuation; hypomethylating agents are often the best treatment option for MDS, and transient cytopenias are expected and manageable. Remember that platelet transfusion thresholds are higher in actively bleeding patients (50,000/µL) versus stable patients (10,000/µL). For pharmacology exams, know that supportive care measures like transfusions often allow continuation of effective but toxic therapies, rather than abandoning treatment entirely.

Question 20

A 70-year-old male with testicular cancer is treated with a regimen including bleomycin. He has a history of smoking but no diagnosed pulmonary disease. After two cycles, he develops a non-productive cough and progressive dyspnea. A chest CT shows bilateral interstitial infiltrates. Bleomycin is discontinued. Which of the following factors is most associated with an increased risk of this specific toxicity and should be carefully managed if he requires future general anesthesia?

  1. Administration of granulocyte colony-stimulating factors (G-CSFs).
  2. Exposure to high concentrations of supplementary oxygen. (correct answer)
  3. Concurrent administration of high-dose corticosteroids.
  4. Pre-existing moderate renal insufficiency (eGFR < 60 mL/min).
Explanation: The patient has developed bleomycin-induced pulmonary toxicity, which presents as pneumonitis that can progress to fatal fibrosis. A key risk factor for exacerbating this condition is exposure to high inspired oxygen concentrations (FiO2), which is thought to increase the production of damaging oxygen free radicals in the lungs. Anesthesiologists must be made aware of prior bleomycin exposure to use the lowest possible FiO2 during surgery. A is incorrect; G-CSFs have been rarely associated with pulmonary issues but are not a primary, well-established risk factor like oxygen. C is incorrect; corticosteroids are used to treat, not cause, bleomycin-induced pneumonitis. D is incorrect; while dose adjustments for renal function are needed for bleomycin, renal insufficiency is not the primary risk factor for its pulmonary toxicity compared to age, cumulative dose, and oxygen exposure.