This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
Methotrexate toxicity is treated by? 
Select and explain. 
A. Folinic acid, B. Folic acid, C. Vitamin B 12, D. Folinic acid+Vitamin B 12
A: Folinic acid
Answer: A: Folinic acid 
Explanation: Ans. is 'a' i.e., Folinic acid Folinic acid rescue o Where it is desired to maximise the effect of methotrexate a potentially fatal dose is given and is followed 24 h later by a dose of folinic acid to terminate its action. o High concentrations of methotrexate are obtained and bone marrow cells recover better than the tumor cells and some degree of useful selectivity is achieved