Lidocaine is a common local anaesthetic and has Class 1b anti-arrhythmic properties. It is an amide-type local anaesthetic and was developed in 1943
It is 70% protein bound to alpha-1-acid glycoprotein. Lidocaine has a more rapid onset of action and longer duration of action than ester-type local anaesthetics such as procaine. It is approximately 90% metabolised in the liver by N-dealkylation (cytochrome CYP1A2 and CYP3A4) to the pharmacologically active metabolites monoethylglycinexylidide and glycinexylidide.
The elimination half-life of lidocaine is approximately 1.5–2 hours in most patients. This may be prolonged in patients with hepatic impairment or congestive heart failure.
Lidocaine 2% may be used to top up an epidural. 20 ml is often combined with epinephrine 1 ml of 1:200,000 and an opiate. After a test dose, 5-8 ml may be given every 2-3 minutes.
Lidocaine is more likely than bupivacaine, prilocaine or procaine to induce transient neurological symptoms (TNS) when used for spinal anaesthesia. These symptoms have been described as pain and dysesthesia in the buttocks, thighs or calves, occurring after the recovery from spinal anaesthesia, usually within 24 hours and resolving within 72 hours.
Video 1: A video showing the technique of epidural placement.