Lidocaine Pharmacology Review

Lidocaine stops neuronal conduction by blocking sodium channels. This action prevents sodium ions from entering the channel and inhibits action potential. By blocking sodium channels in neurons of the skin, this drug prevents action potentials from creating pain perception. Lidocaine also blocks sodium channels in the heart and suppresses neuronal excitability present in ventricular dysrhythmias. It is a Class IB antiarrhythmic.

Lidocaine blocks sodium channels and slows nerve conduction in the heart. This drug also slows the heart's depolarization activity and accelerates repolarization duration. Unlike other antidysrhythmic medications, lidocaine does not cause anticholinergic effects.

As a nonselective amide local anesthetic, lidocaine blocks conduction to both sensory and motor neurons. The degree of blockage depends on the medication's volume and concentration. This medication blocks impulses in the following order: autonomic, somatic sensory, and lastly, somatic motor. This drug can be administered either topically or by injection.

Excessive doses of lidocaine may cause paresthesias, a numbing sensation associated with nerve endings.

Excessive amounts of lidocaine causes CNS excitation and may lead to seizures. Administering a benzodiazepine may be used to manage convulsions.

High IV doses of lidocaine may severely depress the CNS and result in respiration depression. Absorption of lidocaine in the general circulation causes systemic toxicity and may cause respiratory depression. Ensure resuscitation equipment is available nearby.

The CNS excitation phase induced by lidocaine is followed by depressive symptoms such as drowsiness and confusion. In addition, this medication may be absorbed in the general circulation and cause systemic toxicity. Symptoms include CNS depression. It is important to monitor the patient's vital signs and level of consciousness.

Administering a vasoconstrictor (i.e., epinephrine) with lidocaine extends the duration of the local anesthetic. By decreasing local blood flow and delaying systemic absorption of the anesthetic, epinephrine prolongs anesthesia and decreases the risk of toxicity. Delaying systemic absorption of lidocaine allows a lower dosage to obtain the desired effect.