Mastering the medicinal uses of purine is essential for B. Pharm students preparing for pharmacology and clinical pharmacy roles. This set titled ‘Medicinal uses of purine MCQs With Answer’ reviews purine-based drugs, including purine analogs, xanthine oxidase inhibitors (allopurinol, febuxostat), antimetabolites (azathioprine, 6-mercaptopurine, thioguanine), antiviral guanosine analogs (acyclovir, ganciclovir, ribavirin), adenosine and methylxanthines (theophylline, caffeine), and agents targeting purine metabolism (mycophenolate, cladribine). Learn mechanisms, indications, adverse effects, drug interactions, activation pathways (HGPRT, TPMT, XO), dosing principles, monitoring, pharmacogenetics and clinical correlations. This concise, exam-focused overview links biochemical pathways to therapeutic use. Now let’s test your knowledge with 50 MCQs on this topic.
Q1. Which drug is a xanthine oxidase inhibitor commonly used to lower uric acid in gout?
- Allopurinol
- Probenecid
- Colchicine
- Febuxostat
Correct Answer: Allopurinol
Q2. Azathioprine is a prodrug that is converted into which active purine analogue?
- 6-Thioguanine
- 6-Mercaptopurine
- Fludarabine
- Cladribine
Correct Answer: 6-Mercaptopurine
Q3. Inactivation of thiopurines is significantly affected by which enzyme with common pharmacogenetic polymorphisms?
- Guanine deaminase
- Xanthine oxidase
- Thiopurine methyltransferase (TPMT)
- Hypoxanthine-guanine phosphoribosyltransferase (HGPRT)
Correct Answer: Thiopurine methyltransferase (TPMT)
Q4. Allopurinol coadministration increases toxicity of which drug by inhibiting its metabolism?
- Azathioprine
- Colchicine
- Probenecid
- Febuxostat
Correct Answer: Azathioprine
Q5. Which purine analogue is primarily used as an antiviral against herpes simplex virus?
- Ganciclovir
- Acyclovir
- Ribavirin
- Cladribine
Correct Answer: Acyclovir
Q6. Which enzyme deficiency is responsible for Lesch–Nyhan syndrome affecting purine salvage?
- Xanthine oxidase deficiency
- HGPRT deficiency
- Adenine deaminase deficiency
- Purine nucleoside phosphorylase deficiency
Correct Answer: HGPRT deficiency
Q7. Mycophenolate mofetil primarily inhibits which enzyme in purine synthesis?
- Purine nucleoside phosphorylase
- Inosine monophosphate dehydrogenase (IMPDH)
- Adenosine deaminase
- Hypoxanthine-guanine phosphoribosyltransferase
Correct Answer: Inosine monophosphate dehydrogenase (IMPDH)
Q8. Which purine analogue is used for chronic lymphocytic leukemia and is an adenosine analogue?
- Cladribine
- Fludarabine
- Ribavirin
- 6-Mercaptopurine
Correct Answer: Fludarabine
Q9. Which drug is a prodrug of acyclovir with improved oral bioavailability?
- Valacyclovir
- Famciclovir
- Ganciclovir
- Cidofovir
Correct Answer: Valacyclovir
Q10. Which methylxanthine is commonly used as a bronchodilator in asthma and COPD?
- Caffeine
- Theophylline
- Dipyridamole
- Allopurinol
Correct Answer: Theophylline
Q11. Which purine analogue is activated by viral thymidine kinase and used for HSV infections?
- Acyclovir
- Ganciclovir
- Ribavirin
- 6-Mercaptopurine
Correct Answer: Acyclovir
Q12. Ganciclovir is especially indicated for infections caused by which virus?
- Hepatitis B virus
- Cytomegalovirus (CMV)
- Human papillomavirus (HPV)
- Influenza A
Correct Answer: Cytomegalovirus (CMV)
Q13. Which purine-targeting drug inhibits adenosine deaminase and is used in hairy cell leukemia?
- Pentostatin
- Cladribine
- Fludarabine
- Mycophenolate
Correct Answer: Pentostatin
Q14. Which drug is a uricolytic enzyme used in tumor lysis syndrome to rapidly lower uric acid?
- Allopurinol
- Rasburicase
- Febuxostat
- Probenecid
Correct Answer: Rasburicase
Q15. Ribavirin’s antiviral activity involves inhibition of which process?
- Purine salvage via HGPRT
- Viral RNA polymerase and guanosine nucleotide synthesis
- Xanthine oxidase activity
- Inosine monophosphate dehydrogenase exclusively
Correct Answer: Viral RNA polymerase and guanosine nucleotide synthesis
Q16. Which adverse effect is most characteristic of 6-mercaptopurine therapy?
- Nephrotoxicity
- Bone marrow suppression
- Bronchospasm
- Arrhythmia
Correct Answer: Bone marrow suppression
Q17. Febuxostat differs from allopurinol mainly by which property?
- It is a purine analog
- It non-competitively inhibits xanthine oxidase and is non-purine-based
- It is a uricosuric agent
- It is an adenosine receptor agonist
Correct Answer: It non-competitively inhibits xanthine oxidase and is non-purine-based
Q18. Which enzyme converts hypoxanthine to xanthine and xanthine to uric acid?
- HGPRT
- Xanthine oxidase
- IMP dehydrogenase
- Adenosine deaminase
Correct Answer: Xanthine oxidase
Q19. Which purine antagonist is used as immunosuppressant in organ transplantation by inhibiting purine synthesis?
- Mycophenolate mofetil
- Theophylline
- Cladribine
- Acyclovir
Correct Answer: Mycophenolate mofetil
Q20. The activation of 6-mercaptopurine to nucleotides requires which enzyme?
- TPMT
- HGPRT
- Xanthine oxidase
- Adenosine deaminase
Correct Answer: HGPRT
Q21. Which purine drug is known for causing nephrotoxicity via crystalline precipitation if not adequately hydrated?
- Acyclovir
- Valacyclovir
- Ganciclovir
- Allopurinol
Correct Answer: Acyclovir
Q22. Which purine analog is preferentially incorporated into DNA causing strand breaks and used in hairy cell leukemia?
- Cladribine
- Ribavirin
- 6-Mercaptopurine
- Allopurinol
Correct Answer: Cladribine
Q23. Which drug is a guanosine analog that is often used against CMV and has significant bone marrow toxicity?
- Acyclovir
- Ganciclovir
- Ribavirin
- Cladribine
Correct Answer: Ganciclovir
Q24. Which mechanism explains how methylxanthines like theophylline produce bronchodilation?
- Beta-2 receptor antagonism
- PDE inhibition increasing cAMP and adenosine receptor antagonism
- Direct muscarinic receptor activation
- Xanthine oxidase inhibition
Correct Answer: PDE inhibition increasing cAMP and adenosine receptor antagonism
Q25. Which agent increases renal excretion of uric acid and is contraindicated with uricosuric drugs in certain settings?
- Probenecid
- Allopurinol
- Rasburicase
- Febuxostat
Correct Answer: Probenecid
Q26. TPMT deficiency predisposes patients to severe toxicity with which class of drugs?
- Platinum-based chemotherapeutics
- Thiopurines (azathioprine, 6-MP)
- Fluoroquinolones
- Beta-lactams
Correct Answer: Thiopurines (azathioprine, 6-MP)
Q27. Which purine analogue is preferred for cytomegalovirus prophylaxis in transplant recipients?
- Acyclovir
- Ganciclovir/Valganciclovir
- Ribavirin
- Allopurinol
Correct Answer: Ganciclovir/Valganciclovir
Q28. Adenosine is therapeutically used to treat which cardiac condition?
- Ventricular fibrillation
- Paroxysmal supraventricular tachycardia (PSVT)
- Heart block
- Bradycardia
Correct Answer: Paroxysmal supraventricular tachycardia (PSVT)
Q29. Which drug requires phosphorylation by viral kinases to become active, reducing host toxicity?
- Ribavirin
- Acyclovir
- Allopurinol
- Febuxostat
Correct Answer: Acyclovir
Q30. Which medication is contraindicated or used with caution in patients with severe cardiac disease due to arrhythmogenic potential?
- Theophylline
- Allopurinol
- Probenecid
- Rasburicase
Correct Answer: Theophylline
Q31. Which purine metabolism disorder results in accumulation of uric acid and episodic gout due to overproduction?
- HGPRT deficiency (partial, Kelley-Seegmiller variant)
- Adenosine deaminase deficiency
- Orotic aciduria
- Purine nucleoside phosphorylase deficiency
Correct Answer: HGPRT deficiency (partial, Kelley-Seegmiller variant)
Q32. Which antiviral guanosine analogue is effective against CMV and requires phosphorylation by viral kinases?
- Valacyclovir
- Ganciclovir
- Rasburicase
- Allopurinol
Correct Answer: Ganciclovir
Q33. Which purine-based drug’s major toxicity is hepatotoxicity and bone marrow suppression and is used in leukemia maintenance?
- 6-Mercaptopurine
- Theophylline
- Allopurinol
- Ribavirin
Correct Answer: 6-Mercaptopurine
Q34. Which drug directly inhibits inosine monophosphate dehydrogenase causing immunosuppression?
- Mycophenolate mofetil
- Allopurinol
- Cladribine
- Acyclovir
Correct Answer: Mycophenolate mofetil
Q35. Which drug is least likely to be effective against RNA viruses?
- Ribavirin
- Acyclovir
- Interferon (used with ribavirin)
- Favipiravir
Correct Answer: Acyclovir
Q36. Which purine antagonist is most associated with hypersensitivity syndrome including severe rash when combined with allopurinol?
- 6-Mercaptopurine
- Azathioprine
- Ganciclovir
- Ribavirin
Correct Answer: Azathioprine
Q37. Which drug’s mechanism includes incorporation into viral DNA causing chain termination and requires viral kinases for activation?
- Acyclovir
- Allopurinol
- Mycophenolate
- Probenecid
Correct Answer: Acyclovir
Q38. Which purine analogue is converted into 6-thioguanine nucleotides and used in acute leukemia?
- 6-Mercaptopurine
- Thioguanine (6-TG)
- Cladribine
- Ribavirin
Correct Answer: Thioguanine (6-TG)
Q39. Which laboratory parameter is most important to monitor during therapy with azathioprine or 6-MP?
- Liver enzymes and complete blood count (CBC)
- Serum creatinine only
- Serum uric acid only
- Chest X-ray
Correct Answer: Liver enzymes and complete blood count (CBC)
Q40. Which drug is an oral prodrug of penciclovir used for herpes infections?
- Valacyclovir
- Famciclovir
- Ganciclovir
- Ribavirin
Correct Answer: Famciclovir
Q41. Which enzyme is inhibited by allopurinol leading to decreased production of uric acid?
- Purine nucleoside phosphorylase
- Xanthine oxidase
- HGPRT
- IMP dehydrogenase
Correct Answer: Xanthine oxidase
Q42. Excessive doses of theophylline produce toxicity primarily by which mechanism?
- Inhibition of xanthine oxidase
- Overstimulation of central nervous system and cardiac arrhythmias
- Severe bone marrow suppression
- Acute renal failure
Correct Answer: Overstimulation of central nervous system and cardiac arrhythmias
Q43. Which drug is recommended to prevent hyperuricemia caused by tumor lysis syndrome in high-risk chemotherapy?
- Allopurinol or rasburicase depending on severity
- Probenecid alone
- Ganciclovir
- Theophylline
Correct Answer: Allopurinol or rasburicase depending on severity
Q44. Which purine drug’s activation is independent of viral kinases and useful against resistant CMV strains?
- Valacyclovir
- Cidofovir
- Acyclovir
- Famciclovir
Correct Answer: Cidofovir
Q45. Which condition is a classic contraindication to the use of the methylxanthines?
- Uncontrolled seizures
- Severe liver impairment
- Diabetes mellitus
- Hypothyroidism
Correct Answer: Uncontrolled seizures
Q46. Which purine pathway inhibitor would most directly reduce de novo guanine nucleotide synthesis?
- Allopurinol
- Mycophenolate (IMPDH inhibitor)
- Acyclovir
- Probenecid
Correct Answer: Mycophenolate (IMPDH inhibitor)
Q47. Which antiviral purine analogue can cause teratogenicity and is contraindicated in pregnancy?
- Ribavirin
- Acyclovir
- Valacyclovir
- Famciclovir
Correct Answer: Ribavirin
Q48. Which lab abnormality suggests xanthine oxidase inhibition therapy is effective?
- Decreased serum uric acid and increased xanthine levels
- Increased serum uric acid
- Decreased creatinine clearance
- Increased ammonia
Correct Answer: Decreased serum uric acid and increased xanthine levels
Q49. Which drug interaction increases 6-MP plasma levels causing severe toxicity?
- Allopurinol coadministration
- Probenecid coadministration
- Theophylline coadministration
- Valacyclovir coadministration
Correct Answer: Allopurinol coadministration
Q50. For B. Pharm students, which concept best links purine biochemistry to drug action in clinical practice?
- Knowing only drug brand names
- Understanding metabolic pathways, activation enzymes (HGPRT, TPMT), and targets (XO, IMPDH)
- Memorizing adverse effects without mechanisms
- Focusing solely on dosing schedules
Correct Answer: Understanding metabolic pathways, activation enzymes (HGPRT, TPMT), and targets (XO, IMPDH)
