Table 1: Local anaesthetics for the treatment of acute pain

Agent	% solution for analgesic blocks	Duration (hours)	Max. single dose mg/kg. (Total mg in adults* see footnote)	% solution for infusion	Comments
Lignocaine
Infiltration	0.5-1	1-2	7	-	Rapid onset. Dense motor block.
Epidural	1-2	1-2	(500)	0.3-0.7
Plexus or nerve	0.75-1.5	1-3		0.5-1.0
Mepivacaine
Infiltration	0.5-1	1.5-3	7	-	Rapid onset. Dense motor block. Longer action than lignocaine.
Epidural	1-2	1.5-3	(500)	0.3-0.7
Plexus or nerve	0.75-1.5	2-4		0.5-1.0
Prilocaine
Infiltration	0.5-1	1-2	8.5	-	Rapid onset. Dense motor block. Least toxic amide agent. Methaema- globinaemia >600mg
Epidural	2-3	1-3	(600)	0.5-1
Plexus or nerve	1.5-2	1.5-3		0.75-1.25
Bupivacaine
Infiltration	0.125-0.25	1.5-6	3.5	-	Avoid 0.75% in obstetrics. Mainly sensory block at low concen- trations. Cardiotoxic after rapid IV injection.
Epidural	0.25-0.75	1.5-5	(225)	0.0625- 0.125
Plexus or nerve	0.25-0.5	8-24+	0.125- 0.25
Chloroprocaine
Infiltration	1	0.5-1	14	-	Lowest systemic toxicity of all agents. Motor / sensory deficits may follow intrathecal injection.
Epidural	1.5-3	0.5-1	(1000)	0.5-1

Note:* for healthy patients with 1:200,000 adrenaline added to solutions. Maximum doses quoted should be reduced by 40% if solutions do not contain adrenaline. Much lower doses can be lethal if injected directly into a blood vessel.