Singapore Drugs Database

Indication

For production of local or regional anesthesia by infiltration techniques such as percutaneous injection and intravenous regional anesthesia by peripheral nerve block techniques such as brachial plexus and intercostal and by central neural techniques such as lumbar and caudal epidural blocks.

Mechanism of Action

Lidocaine stabilizes the neuronal membrane by inhibiting the ionic fluxes required for the initiation and conduction of impulses thereby effecting local anesthetic action. Lidocaine alters signal conduction in neurons by blocking the fast voltage gated sodium (Na+) channels in the neuronal cell membrane that are responsible for signal propagation. With sufficient blockage the membrane of the postsynaptic neuron will not depolarize and will thus fail to transmit an action potential. This creates the anaesthetic effect by not merely preventing pain signals from propagating to the brain but by aborting their birth in the first place.

Pharmacokinetics

Absorption

Information derived from diverse formulations, concentrations and usages reveals that lidocaine is completely absorbed following parenteral administration, its rate of absorption depending, for example, upon various factors such as the site of administration and the presence or absence of a vasoconstrictor agent.

Distribution

* 0.7 to 2.7 L/kg [healthy volunteers]

Metabolism

Primarily hepatic.

Elimination

Clearance

* 0.64 +/- 0.18 L/min

Toxicity

The oral LD 50 of lidocaine HCl in non-fasted female rats is 459 (346-773) mg/kg (as the salt) and 214 (159-324) mg/kg (as the salt) in fasted female rats. Symptoms of overdose include convulsions, hypoxia, acidosis, bradycardia, arrhythmias and cardiac arrest.

Active Ingredient/Synonyms

2-(Diethylamino)-2',6'-acetoxylidide | 2-(Diethylamino)-N-(2,6-dimethylphenyl)acetamide | alpha-diethylamino-2,6-dimethylacetanilide | Lignocaine | α-diethylamino-2,6-dimethylacetanilide | Lidocaine |