Lidocaine; Uses, Dosage, Side Effects, Interactions

Lidocaine is a local anesthetic and cardiac depressant used as an antiarrhythmic agent. Its actions are more intense and its effects more prolonged than those of procaine but its duration of action is shorter. Lidocaine is a synthetic aminoethylamide with local anesthetic and antiarrhythmic properties. Lidocaine stabilizes the neuronal membrane by binding to and inhibiting voltage-gated sodium channels, thereby inhibiting the ionic fluxes required for the initiation and conduction of impulses and effecting local anesthesia.

A local anesthetic and cardiac depressant used as an antiarrhythmia agent. Its actions are more intense and its effects more prolonged than those of procaine but its duration of action is shorter than that of bupivacaine or prilocaine. It is also used to treat ventricular tachycardia and to perform nerve blocks. Lidocaine mixed with a small amount of adrenaline (epinephrine) is available to allow larger doses for numbing, to decrease bleeding, and to make the numbing effect last longer.

Mechanism of Action of Lidocaine

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.

or

Abnormal, repetitive impulse firing arising from incomplete inactivation of Na+ channels may be involved in several diseases of muscle and nerve, including familial myotonias and neuropathic pain syndromes. Systemic local anesthetics have been shown to have clinical efficacy against myotonias and some forms of neuropathic pain, so we sought to develop an in vitro model to examine the cellular basis for these drugs’ effects. In frog sciatic nerves, studied in vitro by the sucrose-gap method, peptide alpha-toxins from sea anemone (ATXII) or scorpion (LQIIa) venom, which inhibit Na+ channel inactivation, induced repetitively firing compound action potentials (CAPs) superimposed on a plateau depolarization lasting several seconds. The initial spike of the CAP was unaffected, but the plateau and repetitive firing were strongly suppressed by 5-30 uM lidocaine. Lidocaine causes a rapid, concentration-dependent decay of the plateau, quantitatively consistent with blockade of open Na(+) channels. Early and late repetitive firing were equally suppressed by lidocaine with IC50 = 10 uM. After washout of lidocaine and LQIIa, the plateau and repetitive firing remained for > 1 hr, showing that lidocaine had not caused dissociation of channel-bound alpha-toxin. These findings indicate that therapeutic concentrations of lidocaine can reverse the “abnormal” features of action potentials caused by non-inactivating Na+ channels without affecting the normal spike component.
PubMed

Indications of Lidocaine

• Anal Itching
• Pain
• Anesthesia
• Burns, external
• Gastrointestinal surgery
• Gastrointestinal tract examination
• Hemorrhoids
• Local Anesthesia
• Manscaping pain
• Neuropathic pain
• Postherpetic neuralgia
• Postherpetic neuralgia
• Ventricular arrhythmias
• For the 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.
• used for infiltration anesthesia and for nerve block techniques including peripheral, sympathetic, epidural (including caudal), and spinal block anesthesia. /Included in US product label

Contra-Indications of Lidocaine

• Heart block, second or third degree (without pacemaker)
• Severe sinoatrial block (without pacemaker)
• Serious adverse drug reaction to lidocaine or amide local anesthetics
• Hypersensitivity to corn and corn-related products (corn-derived dextrose is used in the mixed injections)
• Concurrent treatment with quinidine, flecainide, disopyramide, procainamide (class I antiarrhythmic agents)
• Prior use of amiodarone hydrochloride
• Adams-Stokes syndrome
• Wolff-Parkinson-White syndrome
• Lidocaine viscous is not recommended by the FDA to treat teething pain in children and infants.

Exercise caution in patients with any of these

• Hypotension not due to arrhythmia
• Bradycardia
• Accelerated idioventricular rhythm
• Elderly patients
• Pseudocholinesterase deficiency
• Intra-articular infusion (this is not an approved indication and can cause chondrolysis)
• Porphyria, especially acute intermittent porphyria; lidocaine has been classified as porphyrogenic because of the hepatic enzymes it induces, although clinical evidence suggests it is not. Bupivacaine is a safe alternative in this case.
• Impaired liver function

Dosage of Lidocaine

• Strengths: 2%; 4%; 5%; 2.5%; 10%; 3%; 1%; 0.5 mg; 0.5%;

Anesthesia

• 2% viscous solution: Gargle 15 mL, undiluted, and spit out or swallow, no less than every 3 hours
  Maximum dose: 300 mg for normal healthy adult – not to exceed 4.5 mg/kg (2 mg/lb), or 8 doses in 24 hours

Side Effects of Lidocaine

Most common

• Blistering, crusting, irritation, itching, or reddening of the skin
• a cough
• cracked, dry, or scaly skin
• Abdominal or stomach discomfort
• low blood pressure,
• difficult, burning, or painful urination
• diarrhea
• symptoms of weakness, muscle pain (myalgia)
• abdominal pain (GI complaints), lactic acidosis (rare)
• low blood levels of vitamin B-12 
• nausea,vomiting
• chest discomfort
• chills, dizziness
• bloating/abdominal distention
• constipation
• heartburn

More common

• chest pain;
• Abdominal or stomach discomfort
• cough or hoarseness
• decreased appetite
• diarrhea
• fast or shallow breathing
• trouble breathing; or
• dangerously high blood pressure (severe headache, blurred vision, buzzing in your ears, anxiety, confusion, chest pain, shortness of breath, uneven heartbeats, seizure)
• lower back or side pain
• muscle pain or cramping
• painful or difficult urination

Less common

• dry mouth
• feeling of thirst
• weakness
• drowsiness
• restlessness
• muscle pains or cramps
• fast or abnormal heartbeat
• severe nausea or vomiting
•  tiredness
•  weakness
• dry hair and skin
• increased feelings of being cold
• pain when you eat or drink
• severe nausea or vomiting

Drug Interactions of Lidocaine

Lidocaine may interact with following drugs, Supplements & may change the efficacy of drugs

• certain beta-adrenergic blockers (e.g., propranolol, sotalol)
• chloroquine
• dapsone
• digoxin
• dofetilide
• flecainide
• mexiletine
• nitrates (e.g., isosorbide dinitrate, isosorbide mononitrate, nitroglycerin)
• nitrofurantoin
• phenobarbital
• phenytoin
• primaquine
• procainamide
• quinidine
• quinine
• sulfonamide antibiotics (“sulfas”; e.g., sulfisoxazole, sulfamethoxazole)
• verapamil

Pregnancy Category of Lidocaine

FDA Pregnancy Category B

Pregnancy

This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Lactation

Lidocaine passes into breast milk. If you are a breastfeeding mother and are taking lidocaine-prilocaine, it may affect your baby. Talk to your doctor about whether you should continue breastfeeding.

References

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