This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Chemotherapy, Subject name: Pharmacology
Treatment for methotrexate poisoning 
Select and explain. 
A. Dietary folic acid, B. Niacin, C. Folinic acid, D. Biotin
C: Folinic acid
Answer: C: Folinic acid 
Explanation: Methotrexate poisoning: The toxicity of Mtx cannot be overcome by folic acid, because it will not be conveed to the active coenzyme form(due to inhibition of DHFA reductase by Mtx) Treatment:- Folinic acid (N5 formyl THFA, cirovorum factor) rapidly reverses the effects. Thymidine also counteracts Mtx toxicity. Ref:- kd tripathi; pg num:- 862