This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Central Nervous system, Subject name: Pharmacology
A patient ingested some unknown substance and presented with myoclonic jerks, seizures, tachycardia and hypotension. ECG shows a hea rate of 120/min. The aerial blood revealed a pH of 7.25, pCO2of 30mm Hg and bicarbonate ions are 15mmol/L. The most likely poisonous agent is: 
Select and explain. 
A. Amanita phylloids, B. Ethylene glycol, C. Imipramine, D. Phencyclidine
C: Imipramine
Answer: C: Imipramine 
Explanation: Ref: KDT 8TH ED. Features are typical of tricyclic antidepressant poisoning. TCAs posses anticholinergic activity that can result in tachycardia. These agents can lead to metabolic acidosis (pH<7.4, HCO3<24mmol/L). Seizures and myoclonic jerks are other features of TCA poisoning.