This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anti-Neoplastic Agents, Subject name: Pharmacology
Which of the following anti neoplastic drug causes hepatotoxicity: 
Select and explain. 
A. 6- mercaptopurine, B. 5- flurouracil, C. Doxorubicin, D. Etoposide
A: 6- mercaptopurine
Answer: A: 6- mercaptopurine 
Explanation: Ans. (a) 6- mercaptopurineRef.: KDT 6th ed. / 820* 6 mercaptopurine (6-MP) is a purine analogue which is metabolized by xanthine oxidase* It is a competitive inhibitor of DNA.* Allopurinol is NOT given along with 6-MP because allopurinol inhibits xanthine oxidase enzyme, which leads to increased toxicity due to accumulation of xanthine.Anti-Neoplastic DrugsTheir Side EffectCyclophosphamide, ifosphamideHemorrhagic cystitisProcarbazineDisulfiram like reactionBleomycin, busulfanPulmonary fibrosisVincristine, vinblastinePeripheral neuropathyCisplatinOtotoxicity, Nephrotoxicity6Mercaptopurine, 6ThioguanineHepatotoxicityDoxorubicin, DaunorubicinCardiotoxic