Comparative toxicity of local anaesthetics:
Drug
Plasma Concentration
Signs
Lignocaine
5 mcg/ml
Initial CNS symptoms
>12 mcg/ml
Convulsions
>24 mcg/ml
Cardiovascular collapse
Bupivacaine
2-4 mcg/ml
Convulsions
>4 mcg/ml
Ventricular arrhythmias Intractableventricular fibrillation
Etidocaine
2 mcg/ml
Convulsions