Question: What is the maximum safe dose of LA drugs?

Answer: The maximum allowable dose for some of the commonly used LA drugs is given in Table 1.

Toxicity of local anaesthetics is additive. If using one local anaesthetic, the maximum safe dose of a second agent will be proportionally reduced.

A normogram has recently been developed for calculation of the safe allowable dose. Most nerve blocks are more dependent on volume of drug injected than the total dose. Therefore, if more volume is needed, it is better to dilute the LA drug with 0.9% saline than to add more local anaesthetic and increase the dose unnecessarily.