This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Autacoids, Subject name: Pharmacology
The antidote of choice in paracetamol poisoning is: 
Select and explain. 
A. Flumazenil, B. Siodium bicarbonate, C. N-acetylcysteine, D. Methylene Blue
C: N-acetylcysteine
Answer: C: N-acetylcysteine 
Explanation: Cytochromes P450 conve approximately 5% of paracetamol to a highly reactive intermediary metabolite, N-acetyl-p-benzoquinone imine (NAPQI). Under normal conditions, NAPQI is detoxified by conjugation with glutathione to form cysteine and mercapturic acid conjugates N-acetylcysteine works to reduce paracetamol toxicity by replenishing body stores of the antioxidant glutathione. Glutathione reacts with the toxic NAPQI metabolite so that it does not damage cells and can be safely excreted DOC Injection - N acetylcysteine DOC Oral- methionine Ref: KD Tripathi 8th ed