Lidocaine: an effective local anesthetic

Lidocaine is an effective pain reliever. Local anesthetics inhibit the ionic currents involved in the formation of the irritant, due to which the analgesic effect is achieved. Lidocaine stabilizes neuronal membranes, suppresses nerve conduction, and reduces the degree of depolarization.

When is lidocaine indicated?

The range of indications for Lidocaine solution includes the following conditions:

Local anesthesia required for manipulations in ophthalmology, ENT practice, dentistry, and surgery.
The use of cephalosporin group of antibacterial drugs as a solvent, the administration of which is characterized by a pronounced pain effect.

Lidocaine for injection allows you to anesthetize the desired area of skin or mucous membrane for several hours, which will be enough for medical manipulation accompanied by increased sensitivity.

Lidocaine gel –

There are both professional lidocaine-based gels for dental clinics and those that can be bought at any pharmacy. An example of a common gel with lidocaine is the drug “Kamistad”. This gel contains lidocaine and chamomile extract as active ingredients. Created specifically for application to the oral mucosa. It has an analgesic and slight anti-inflammatory effect.

How is lidocaine solution used?

The local anesthetic solution is pre-tested on a separate area of the skin, which makes it possible to assess the presence or absence of an individual negative reaction to the drug.

The dosage of lidocaine solution depends on the type of anesthesia:

Terminal type of anesthesia involves local application of a solution (2 mg per kg of body weight), maximum 20 ml for an adult patient. The effect lasts no more than 30 minutes.
Conduction type of anesthesia. The dosage depends on the size of the area that needs to be anesthetized. Maximum dose 20 ml.
In ophthalmology, the solution is instilled into the conjunctival sac.
Epidural anesthesia – 22-30 ml of solution.
Pain relief in obstetrics and gynecology – 20-30 ml of solution.
In childhood, the dosage is determined individually (on average 3.5-4 mg per kg of weight).

To prevent the development of side effects, the solution must be administered strictly in recommended dosages. The medication Lidocaine, the instructions for use of which contains all the necessary dosages, must be prescribed after a detailed study of the anamnesis.

Lidocaine

For infiltration anesthesia

: intradermal, subcutaneous, intramuscular. Apply lidocaine solution 5 mg/ml (maximum dose 400 mg)

For blocking peripheral nerves and nerve plexuses

: perineural, 10-20 ml of a solution of 10 mg/ml or 5-10 ml of a solution of 20 mg/ml (no more than 400 mg).

For conduction anesthesia

: solutions of 10 mg/ml and 20 mg/ml (no more than 400 mg) are used perineurally.

For epidural anesthesia

: epidural, solutions 10 mg/ml or 20 mg/ml (not more than 300 mg).

For spinal anesthesia

: subarachnoid, 3-4 ml of a solution of 20 mg/ml (60-80 mg).

In ophthalmology

: a solution of 20 mg/ml is instilled into the conjunctival sac, 2 drops 2-3 times at intervals of 30-60 seconds, immediately before surgery or examination.

To prolong the effect of lidocaine, it is possible to add ex tempore 0.1% adrenaline solution (1 drop per 5-10 ml of lidocaine solution, but no more than 5 drops for the entire volume of the solution).

It is recommended to reduce the dose of lidocaine in elderly patients and patients with liver diseases (cirrhosis, hepatitis) or with reduced hepatic blood flow (chronic heart failure) by 40 - 50%.

As an antiarrhythmic agent

: intravenously.
Lidocaine solution for intravenous administration 100 mg/ml can only be used after dilution!
25 ml of a 100 mg/ml solution should be diluted with 100 ml of saline to a lidocaine concentration of 20 mg/ml. This diluted solution is used to administer the loading dose. Administration begins with a loading dose of 1 mg/kg (over 2-4 minutes at a rate of 25-50 mg/min) followed immediately by a continuous infusion at a rate of 1-4 mg/min. Due to rapid distribution (half-life approximately 8 minutes), 10-20 minutes after the first dose, the concentration of the drug in the blood plasma decreases, which may require repeated bolus administration (against the background of continuous infusion) at a dose equal to 1/2-1/3 loading dose, with an interval of 8-10 minutes.

The maximum dose in 1 hour is 300 mg, per day - 2000 mg.

The intravenous infusion is usually given for 12 to 24 hours with continuous ECG monitoring, after which the infusion is stopped to assess the need for changes in the patient's antiarrhythmic therapy.

The rate of drug elimination is reduced in heart failure and liver dysfunction (cirrhosis, hepatitis) and in elderly patients, which requires a reduction in the dose and rate of drug administration by 25-50%.

For chronic renal failure, no dose adjustment is required.

Adverse reactions

If used incorrectly, adverse reactions may occur:

Dizziness, drowsiness, convulsions, sensory disturbances.
Tinnitus.
Changes in blood pressure, cardiac dysfunction.
Nausea, vomiting.
Feeling of heat, swelling at the injection site.
Burning sensation, thrombophlebitis.

The list of adverse reactions is much wider, so it is necessary to monitor the patient’s condition after administration of the lidocaine solution.

Contraindications to the use of lidocaine solution

The use of the drug is prohibited in patients with individual intolerance to the active substance. Lidocaine injections are also prohibited for use in the following conditions:

The first few months after myocardial infarction.
Severe cardiac pathologies with bradycardia.
Infectious process at the injection site.
Period of pregnancy, lactation.
Children's age (up to 15 years).
Convulsions due to epilepsy.

In these conditions, the use of lidocaine solution is not recommended.

Pharmacokinetics

The time to reach the maximum concentration in the blood plasma after intramuscular administration is 5-15 minutes, with a slow intravenous infusion without an initial saturating dose - after 5-6 hours (in patients with acute myocardial infarction - up to 10 hours). 50-80% of lidocaine binds to blood plasma proteins. Rapidly distributed (half-life of the distribution phase - 6-9 minutes) in organs and tissues with good perfusion, including the heart, lungs, liver, kidneys, then muscle and adipose tissue. Penetrates the blood-brain and placental barriers and is secreted into breast milk (up to 40% of the concentration in maternal plasma). Metabolized mainly in the liver (90-95% of the dose) with the participation of microsomal enzymes with the formation of active metabolites - monoethylglycine xylidide and glycine xylidide, which have a half-life of 2 hours and 10 hours, respectively. Metabolic intensity decreases in liver diseases (can range from 50 to 10% of the normal value); in case of impaired liver perfusion in patients after myocardial infarction and/or with chronic heart failure. The half-life of continuous infusion over 24-48 hours is about 3 hours; if renal function is impaired, it can increase 2 or more times. Excreted in bile and urine (up to 10% unchanged). Acidification of urine increases the excretion of lidocaine.

Interaction of the solution with other drugs

Lidocaine is not recommended to be combined with the following groups of drugs at the same time:

Analgesics of the narcotic group - threatens respiratory depression.
Anticoagulants – increases the risk of bleeding.
Cardiac glycosides – their effectiveness decreases.
Novocaine group – increases muscle relaxation.
The standard is a negative effect on respiratory function.

Lidocaine solution should be combined with extreme caution in diseases of the heart and nervous system, accompanied by systematic use of drugs.

Lidocaine Bufus, 100 mg/ml, solution for injection, 2 ml, 10 pcs.

The toxicity of lidocaine increases when it is used simultaneously with cimetidine and propranolol due to an increase in the concentration of lidocaine; this requires a reduction in the dose of lidocaine. Both drugs reduce hepatic blood flow. In addition, cimetidine inhibits microsomal activity. Ranitidine slightly reduces the clearance of lidocaine, which leads to an increase in its concentration in the blood. Antiviral agents (eg, amprenavir, atazanavir, darunavir, lopinavir) can also cause an increase in lidocaine serum concentrations.

Hypokalemia caused by diuretics may reduce the effect of lidocaine when used concomitantly.

Lidocaine should be used with caution in patients receiving local anesthetics or agents structurally similar to amide-type local anesthetics (eg, antiarrhythmics such as mexiletine, tocainide) since systemic toxic effects are additive.

Separate drug interaction studies have not been conducted between lidocaine and class III antiarrhythmics (eg, amiodarone), but caution is advised.

In patients concomitantly receiving antipsychotics that prolong or have the potential to prolong the QT interval (e.g., pimozide, sertindole, olanzapine, quetiapine, zotepine), prenylamine, epinephrine (with occasional intravenous administration), or 5-HT3-serotonin receptor antagonists (e.g., tropisetron, dolasetron), the risk of developing ventricular arrhythmias may increase.

Concomitant use of quinupristin/dalfopristin may increase lidocaine concentrations and thus increase the risk of developing ventricular arrhythmias; their simultaneous use should be avoided.

Patients receiving concomitant muscle relaxants (eg, suxamethonium) may have an increased risk of enhanced and prolonged neuromuscular blockade.

Cardiovascular insufficiency has been reported following the use of bupivacaine in patients receiving verapamil and timolol; lidocaine is similar in structure to bupivacaine.

Dopamine and 5-hydroxytryptamine lower the seizure threshold in patients receiving lidocaine.

Opioids appear to have a convulsant effect, as supported by evidence that lidocaine lowers the seizure threshold to fentanyl in humans.

Combinations of opioids and antiemetics, sometimes used for sedation in children, may lower the seizure threshold to lidocaine and increase its central nervous system depressant effects.

Use of epinephrine with lidocaine may reduce systemic absorption, but inadvertent intravenous administration increases the risk of ventricular tachycardia and ventricular fibrillation.

The simultaneous use of other antiarrhythmics, beta-blockers and blockers of “slow” calcium channels can further reduce AV conduction, ventricular conduction and contractility.

The simultaneous use of vasoconstrictors increases the duration of action of lidocaine.

Concomitant use of lidocaine and ergot alkaloids (eg, ergotamine) can cause severe hypotension.

Caution must be exercised when using sedatives as they may interfere with the action of lidocaine on the central nervous system.

Caution should be exercised with long-term use of antiepileptic drugs (phenytoin), barbiturates and other inhibitors of liver microsomal enzymes, as this may lead to decreased effectiveness and, as a result, an increased need for lidocaine. On the other hand, intravenous administration of phenytoin may enhance the depressant effect of lidocaine on the heart.

Ethyl alcohol, especially with prolonged abuse, can reduce the effect of the drug.

Lidocaine is not compatible with amphotericin B, methohexitone, nitroglycerin.

With the simultaneous use of lidocaine with narcotic analgesics, an additive effect develops, which is used during epidural anesthesia, but increases the depression of the central nervous system and respiration.

Vasoconstrictors (epinephrine, methoxamine, phenylephrine) can cause increased blood pressure and tachycardia.

Use with monoamine oxidase inhibitors (furazolidone, procarbazine, seleginine) increases the risk of lowering blood pressure.

Guanadrel, guanethidine, mecamylamine, trimethaphan camsylate increase the risk of a pronounced decrease in blood pressure and bradycardia.

Anticoagulants (including ardeparin sodium, dalteparin sodium, danaparoid sodium, enoxaparin sodium, heparin, warfarin and others) increase the risk of bleeding.

Lidocaine reduces the cardiotonic effect of digitoxin.

Lidocaine reduces the effect of antimyasthenic drugs, enhances and prolongs the effect of muscle relaxants.

When treating the injection site with disinfectant solutions containing heavy metals, the risk of developing a local reaction in the form of pain and swelling increases.

Mixing lidocaine with other medications is not recommended.

special instructions

Lidocaine injection should only be done under the supervision of a physician. Treatment should be carried out under ECG control.

Before starting treatment, it is recommended to examine the level of potassium in the blood, since if its content is reduced, the effectiveness of the drug decreases.

The drug has an effect on the central nervous system, so it is not recommended to drive or engage in potentially life-threatening activities while using it.

Careful monitoring is required for patients prone to seizures, as even small doses may enhance the convulsive effect.

It is necessary to combine lidocaine with caution with those drugs that increase its bioavailability or slow down its elimination, which can be especially dangerous in case of end-stage renal failure.

With intramuscular administration of lidocaine solution, increased activity of creatine phosphokinase may be observed, which prevents the diagnosis of myocardial infarction.

Rapid administration of lidocaine solution can lead to a sharp decrease in blood pressure, with the possibility of collapse. In this case, the toxic effect of the drug with its cardiotoxic effect should also be considered.

Indications for use

Infiltration (including subconjunctival), conduction (including retrobulbar, parabulbar anesthesia), spinal and epidural anesthesia.

Relief of persistent paroxysms of ventricular tachycardia (including during myocardial infarction and cardiac surgery), prevention of repeated ventricular fibrillation in acute coronary syndrome and repeated paroxysms of ventricular tachycardia (usually within 12-24 hours), ventricular arrhythmias caused by glycoside intoxication (use a solution with concentration 100 mg/ml).