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: Anaesthesia
Which of the following local anaesthetic should not be alkalinized with soda bicarbonate 
Select and explain. 
A. Lignocaine, B. Procaine, C. Bupivacaine, D. Benzocaine
C: Bupivacaine
Answer: C: Bupivacaine 
Explanation: Local anaesthetic drug if dissociated –it wont act on sodium channel.
So drug is kept undissociated by adding soda bicarbonate to maintain pka 7.7→ 8.2
But for bupivacaine soda bicarbonate is not used as it gets precipitated.