Cytarabine MCQs With Answer

Cytarabine MCQs With Answer

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Cytarabine MCQs With Answer are tailored for B.Pharm students to deepen understanding of cytarabine (cytosine arabinoside), a pyrimidine antimetabolite used mainly in acute myeloid leukemia. This focused introduction links mechanism of action (activation to Ara‑CTP and inhibition of DNA synthesis), pharmacokinetics (rapid deamination by cytidine deaminase), routes of administration (IV, subcutaneous, intrathecal), dosing concepts (schedule‑dependence), resistance mechanisms, and key toxicities such as myelosuppression and cerebellar neurotoxicity. These targeted, clinically relevant MCQs emphasize monitoring, safe handling, adverse‑effect prevention, and clinical decision‑making to prepare you for exams and pharmacy practice. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. Which statement best describes the primary mechanism of action of cytarabine?

  • Intercalation into DNA causing strand breaks
  • Topoisomerase II inhibition
  • Inhibition of DNA polymerase after intracellular conversion to Ara‑CTP
  • Alkylation of guanine bases

Correct Answer: Inhibition of DNA polymerase after intracellular conversion to Ara‑CTP

Q2. Which enzyme is essential for the initial phosphorylation and activation of cytarabine to its active metabolite?

  • Cytidine deaminase
  • Thymidine kinase
  • Deoxycytidine kinase (dCK)
  • Xanthine oxidase

Correct Answer: Deoxycytidine kinase (dCK)

Q3. Cytarabine is most active against tumor cells in which phase of the cell cycle?

  • G1 phase
  • S phase
  • G2 phase
  • M phase

Correct Answer: S phase

Q4. Which pair of adverse effects are most characteristically associated with cytarabine therapy?

  • Cardiotoxicity and nephrotoxicity
  • Myelosuppression and cerebellar neurotoxicity
  • Pulmonary fibrosis and ototoxicity
  • Hypoglycemia and pancreatitis

Correct Answer: Myelosuppression and cerebellar neurotoxicity

Q5. A common mechanism of resistance to cytarabine involves which cellular change?

  • Increased expression of deoxycytidine kinase
  • Decreased activity of deoxycytidine kinase
  • Overexpression of thymidylate synthase
  • Enhanced activation to Ara‑CTP

Correct Answer: Decreased activity of deoxycytidine kinase

Q6. Which of the following routes of administration is NOT commonly used for cytarabine?

  • Intravenous infusion
  • Subcutaneous injection
  • Oral administration
  • Intrathecal injection

Correct Answer: Oral administration

Q7. High‑dose cytarabine commonly causes ocular toxicity; which preventive measure is recommended during high‑dose therapy?

  • Systemic antibiotics
  • Prophylactic topical corticosteroid eye drops
  • Topical antiviral therapy
  • Routine ocular radiation

Correct Answer: Prophylactic topical corticosteroid eye drops

Q8. Cytarabine is inactivated primarily by which metabolic reaction?

  • Methylation by methyltransferases
  • Oxidation by cytochrome P450
  • Deamination by cytidine deaminase to an inactive uracil metabolite
  • Glucuronidation in the liver

Correct Answer: Deamination by cytidine deaminase to an inactive uracil metabolite

Q9. The primary hematologic malignancy for which cytarabine is a cornerstone drug is:

  • Chronic lymphocytic leukemia (CLL)
  • Hodgkin lymphoma
  • Acute myeloid leukemia (AML)
  • Multiple myeloma

Correct Answer: Acute myeloid leukemia (AML)

Q10. What is the main pharmacologic advantage of liposomal (sustained‑release) formulations of intrathecal cytarabine?

  • Reduced systemic myelosuppression
  • Increased renal clearance
  • Prolonged cerebrospinal fluid exposure and extended dosing interval
  • Enhanced oral bioavailability

Correct Answer: Prolonged cerebrospinal fluid exposure and extended dosing interval

Q11. Which laboratory test is essential to monitor during cytarabine therapy to detect the most common dose‑limiting toxicity?

  • Liver function tests (ALT/AST)
  • Serum creatinine
  • Complete blood count (CBC) with differential
  • Serum amylase and lipase

Correct Answer: Complete blood count (CBC) with differential

Q12. The active intracellular triphosphate metabolite of cytarabine is known as:

  • Ara‑UMP
  • Ara‑CDP
  • Ara‑CTP
  • Ara‑GTP

Correct Answer: Ara‑CTP

Q13. The inactive primary metabolite of cytarabine that is excreted in urine is called:

  • Ara‑U
  • Ara‑C‑glucuronide
  • Ara‑N
  • Ara‑P

Correct Answer: Ara‑U

Q14. Which clinical scenario most increases the risk of cerebellar toxicity with cytarabine?

  • Low‑dose subcutaneous therapy in young adults
  • High‑dose intravenous therapy, especially in elderly patients
  • Single low oral dose
  • Topical application

Correct Answer: High‑dose intravenous therapy, especially in elderly patients

Q15. Regarding pregnancy, cytarabine is best described as:

  • Safe in all trimesters
  • Contraindicated due to teratogenicity
  • Recommended for fertility preservation
  • Only safe during lactation

Correct Answer: Contraindicated due to teratogenicity

Q16. Because cytarabine is S‑phase specific, which dosing strategy typically increases cancer cell kill?

  • Single large bolus dose infrequently
  • Continuous infusion or frequent dosing to increase S‑phase exposure
  • Once monthly intramuscular injection
  • Intermittent topical pulses

Correct Answer: Continuous infusion or frequent dosing to increase S‑phase exposure

Q17. What clinical monitoring is most appropriate to detect early cerebellar toxicity during high‑dose cytarabine treatment?

  • Serial uric acid measurements
  • Frequent neurological assessments focusing on gait and speech
  • Daily chest X‑rays
  • Routine audiometry

Correct Answer: Frequent neurological assessments focusing on gait and speech

Q18. Cellular uptake of cytarabine into leukemic cells primarily uses which transporter?

  • P‑glycoprotein (P‑gp)
  • Human equilibrative nucleoside transporter 1 (hENT1)
  • Organic anion transporter (OAT)
  • Glucose transporter (GLUT1)

Correct Answer: Human equilibrative nucleoside transporter 1 (hENT1)

Q19. Incorporation of Ara‑CTP into DNA leads to which direct effect on DNA synthesis?

  • Enhanced DNA ligation
  • Chain termination and inhibition of DNA polymerase
  • Increased telomerase activity
  • Direct DNA cross‑linking

Correct Answer: Chain termination and inhibition of DNA polymerase

Q20. In the treatment of AML, cytarabine is commonly used during which phase of therapy?

  • Induction only
  • Consolidation after remission induction
  • Only for palliative care
  • Prophylactic therapy for unrelated cancers

Correct Answer: Consolidation after remission induction

Q21. Which non‑hematologic toxicity is commonly seen with cytarabine therapy?

  • Mucositis
  • Cardiomyopathy
  • Ototoxicity
  • Severe hypoglycemia

Correct Answer: Mucositis

Q22. Regarding intrathecal cytarabine administration, which statement is correct?

  • It does not penetrate cerebrospinal fluid and is ineffective
  • Intrathecal administration achieves therapeutic CSF concentrations
  • Intrathecal route is preferred for systemic disease control
  • Oral cytarabine is preferred for CNS involvement

Correct Answer: Intrathecal administration achieves therapeutic CSF concentrations

Q23. There is no specific antidote for cytarabine overdose. The most appropriate initial approach is:

  • Administer leucovorin rescue immediately
  • Supportive care and close monitoring, including management of complications
  • Gastric lavage and high‑dose naloxone
  • Immediate hemodialysis to remove cytarabine

Correct Answer: Supportive care and close monitoring, including management of complications

Q24. Cytarabine is chemically classified as a:

  • Purine analog
  • Platinum compound
  • Pyrimidine nucleoside analog
  • Monoclonal antibody

Correct Answer: Pyrimidine nucleoside analog

Q25. Which safety measure is mandatory when handling cytarabine in the pharmacy?

  • No special precautions are needed
  • Use of cytotoxic drug‑handling precautions and appropriate PPE
  • Only handwashing after preparation is sufficient
  • Heating the vial prior to use to deactivate the drug

Correct Answer: Use of cytotoxic drug‑handling precautions and appropriate PPE

Q26. Before initiating cytarabine in patients with high tumor burden, which laboratory should be assessed to anticipate tumor lysis syndrome?

  • Serum uric acid
  • Fasting blood glucose
  • Serum magnesium only
  • Serum vitamin B12

Correct Answer: Serum uric acid

Q27. The pharmacokinetic characteristic of cytarabine that influences dosing frequency is:

  • Extremely long half‑life allowing once‑weekly dosing
  • Short plasma half‑life due to rapid deamination, necessitating frequent dosing or infusion
  • Complete oral bioavailability
  • Exclusive hepatic excretion unchanged

Correct Answer: Short plasma half‑life due to rapid deamination, necessitating frequent dosing or infusion

Q28. Which ocular condition is specifically associated with cytarabine and requires monitoring during therapy?

  • Glaucoma
  • Conjunctivitis and keratopathy
  • Retinal detachment
  • Optic neuritis only in pediatrics

Correct Answer: Conjunctivitis and keratopathy

Q29. Which statement about cytarabine‑induced cerebellar toxicity is TRUE?

  • It is unrelated to dose and occurs unpredictably in all patients
  • It is more likely at higher doses and in elderly patients, and early detection may allow recovery
  • It is irreversible regardless of intervention
  • It presents primarily as chest pain and dyspnea

Correct Answer: It is more likely at higher doses and in elderly patients, and early detection may allow recovery

Q30. Which clinical advantage explains the use of continuous infusion cytarabine over intermittent bolus in some regimens?

  • Continuous infusion selectively spares S‑phase cells
  • Continuous infusion increases duration of exposure during S‑phase, potentially improving cytotoxicity
  • Bolus dosing eliminates the need for monitoring
  • Continuous infusion prevents all adverse effects

Correct Answer: Continuous infusion increases duration of exposure during S‑phase, potentially improving cytotoxicity

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