Lignocaine toxicity

Question.

217. Cardiac or central nervous system toxicity may result when standard lidocaine doses are administered to patients with circulatory failure. This may be due to the following reason:

1. Lidocaine concentration are initially higher in relatively well perfused tisseues such as brain and heart.

2. Histamine receptors in brain and heart gets suddenly activated in circulatory failure.

3. There is a sudden out-burst of release of adreneline, noradreneline and dopamine in brain and heart.

4. Lidocaine is converted into a toxic metabolite due to its longer stay in liver.

Answer

1. Lidocaine concentration is initially higher in relatively well perfused tisseues such as brain and heart.

Reference

Harrison 15^th Page 425 and Figure 70.1

Satoskar 17^th Edition Page 384

Goodman Gillman 10^th Edition

Quality

Reader, if you had read it

Status

New

QTDF

Harrison

Discussion

Lidocaine is a rapidly active drug. In circulatory failure, due to decreased hepatic flow, the metabolism of lidocaine is hampered and this leads to high levels in blood and obviously the high levels affect the well perfused tissues

Explanation

Lidocaine concentration are initially higher in relatively well perfused tisseues such as brain and heart. And this is the reason for Cardiac or Central nervous system toxicity when Standard Lignocaine is given to this patients

Comments

Question for Anaesthetists

Tips

A word about Ester and Amide Local Anaesthetics.

If the Name of the Anaesthetic agent has two times the alphabet “i” it is an amide eg Prilocaine, Lignocaine, Dibucaine.

If the Name of the Anaesthetic agent has the alphabet “i” only once it is an ester eg Cocaine, Tetracaine, Benzocaine.