Lidocaine

Lidocaine
Drug class	Amino amide local anaesthetic
Maximum dose	4.5 mg/kg with plain lidocaine; 7 mg/kg with adrenaline; Note: Intercostal block safe dose is 10 times less.
Onset of action	2-5 minutes.
Duration of action	Tissue infiltration: 75-90 mins, or 120-180 mins with adrenaline; Nerve blocks: 2-3 hours, or 3-5 hours with adrenaline.

This article is a stub.

Lidocaine was the first clinically used amide local anesthetic in 1948. It is widely used because of its potency; rapid onset; tissue penetration; and effectiveness in infiltration, peripheral nerve block, and both epidural and spinal blocks. In peripheral nerve blockage 1-1.5% is sufficient to produce a motor blockade, while for epidural and spinal blocks higher strengths are used.

Chemical Structure

Formulations

Lidocaine Cream

Lidocaine cream is not readily available in New Zealand and is not subsidised. It has to be ordered over the internet.

Haim International for 10.56% lidocaine cream, apply twice daily
4% Lidocaine patches can be purchased from ebay, brand name is Salonpas. They last for 8 hours.

Toxicity

Main article: Local Anaesthetic Toxicity

The central nervous system is where the premonitory signs of toxicity occur. Early symptoms include circumoral numbness, tongue paraesthesia, and dizziness. Patients may complain of sensory disturbance such as tinnitus and blurred vision. There may be excitatory signs, such as restlessness, agitation, nervousness, or paranoia. These may progress to muscle twitching and seizures. With severe toxicity, CNS depression can occur with coma.

Cardiovascular effects with hypotension and bradycardia can occur as a result of a relative overdose with neuraxial blockage or nerve blocks nerve the CNS. Unintentional intravascular injection produces severe cardiotoxic reactions which include hypotension, atrioventicular heart block, idioventricular rhythms, ventricular tachycardia, and ventricular fibrillation. Even premonitory signs can progress to cardiotoxicity and so any reaction should be dealt with seriously.^[2]