Xylocaine: History, Administration, Mechanism of Action, Medical Uses, Presentations, Adverse Effects and Interactions

Also known as lidocaine or lignocaine, it is a medication used on the skin to stop the itching and pain of certain skin conditions.

For example:

  • Scratches
  • Minor burns
  • Eczema.
  • Insect bites.
  • Itching caused by hemorrhoids and certain other problems of the genital and / or anal area.

Some forms of this medication are also used to decrease discomfort or pain during certain procedures or medical tests (for example, sigmoidoscopy, cystoscopy).

Thanks to the anesthetic properties of xylocaine it has the ability to cause temporary numbness, loss of sensitivity in the skin and mucous membranes.

Lidocaine can also be used to make nerve blocks and to treat ventricular tachycardia .

If we mix a small amount of epinephrine with xylocaine, it would result in higher doses for numbness, so that the numbing effect lasts longer and to reduce bleeding.

Generally its effect as an injectable presentation begins in four minutes and lasts from half an hour to three hours.

The xylocaine in its topical presentation and in aerosol, can be applied directly on the skin or mucous membranes to numb the area.

Lidocaine decreases the rate of heart contractions by blocking the sodium channels.

History

Lidocaine, the first local anesthetic of the amino-amide type, was first synthesized under the name ‘xylocaine’ by the Swedish chemist Nils Löfgren in 1943.

His colleague Bengt Lundqvist performed the first injection anesthesia experiments on himself.

It was marketed for the first time in 1949.

Administration

  • Before use on the skin, clean and dry the affected area as directed.
  • You should usually place 2 to 3 times a day or as directed, a thin layer of medicine on the affected area of ​​the skin.
  • If you are using the spray, shake the container well before using it.
  • Hold the can 3-5 inches (8-13 centimeters) from the affected area, spray until moist.
  • If the affected area is on your face, spray the medication on your hand and apply it to your face.
  • Do not spray near your eyes, nose or mouth.
  • If you are using the foam, shake the container well before use. Spray the foam on your hand and apply it on the affected area.
  • Do not use on large areas of the body, cover the area with waterproof bandages or plastic, or apply heat unless your doctor tells you to. This can cause serious side effects.
  • Unless you are treating a specific area of ​​the hands, you should wash them immediately.
  • Avoid getting the product into the eyes, nose or ears. If the medication enters these areas, rinse the area immediately with clean water.
  • The dose is based on your medical condition and response to therapy.
  • You should not use this product more often, in larger amounts or for longer than recommended by your doctor.
  • If you are using a product without a prescription, follow all instructions on the product package or use your doctor’s instructions.
  • If there is an infection or pain in the area to be treated, do not use this medication without first consulting your doctor.
  • If your condition does not improve or gets worse, tell your doctor immediately.

Mechanism of action

Xylocaine alters signal conduction in neurons by blocking the fast channels of sodium electrolytes (Na +) regulated by voltage in the neuronal cell membrane responsible for the propagation of the signal.

With sufficient blockade, the membrane of the postsynaptic neuron will not depolarize and, therefore, will not transmit an action potential.

This creates the anesthetic effect not only by preventing pain signals from spreading to the brain, but by stopping them before they begin.

Careful titration allows a high degree of selectivity in blocking sensory neurons, while higher concentrations also affect other neuronal signaling modalities.

The same principle applies for the actions of this medicine in the heart.

Blocking the sodium channels in the conduction system, as well as the heart muscle cells, raises the depolarization threshold, making the heart less likely to initiate or conduct early action potentials that can cause an arrhythmia.

Medical uses

Local anesthetic:

The effectiveness of xylocaine as a local anesthetic can be measured by the duration of long periods of time and by its onset of rapid action.

Consequently, xylocaine is suitable for anesthesia, blockage and superficial infiltration.

Doctors prefer longer-acting substances such as bupivacaine and, depending on the procedure, spinal and epidural anesthesia.

Adrenaline vasoconstricts arteries, which delays the reabsorption of xylocaine and reduces bleeding, almost doubling the duration of anesthesia.

Xylocaine is one of the local anesthetics most commonly used in dentistry .

It can be administered in multiple ways, more often as nerve block or infiltration, depending on the type of treatment performed and the area of ​​the mouth in which it was worked.

Xylocaine makes local numbness and pH buffering less painful.

In ophthalmological procedures, lidocaine drops can be applied to the eyes.

There is evidence that for pain in sites where skin grafts have been done and for neurotic pain, lidocaine helps to alleviate those discomforts.

For the treatment of premature ejaculation it serves as a local anesthetic agent.

Cardiac arrhythmia:

Xylocaine is also the most important antiarrhythmic drug.

Xylocaine is used intravenously (if amiodarone is not available or is not contraindicated) for the treatment of ventricular arrhythmias (cardioversion, acute myocardial infarction, cardiac catheterization or digoxin poisoning).

After defibrillation, vasopressors and CPR have been started, xylocaine should be administered as directed.

A routine preventive dose after a myocardial infarction is no longer recommended since the overall benefit is not convincing.

Epilepsy:

Intravenous lidocaine has the potential to control seizures.

The optimal anticonvulsant dose of lidocaine is unknown.

This medication should be applied only if phenobarbital does not stop seizures.

Others:

Inhaled xylocaine has antitussive properties, which can help reduce the cough reflex.

This type of presentation can be used so that patients who need to be intubated feel more comfortable and as a safety measure, since it reduces any tracheal damage and the incidence of cough that may manifest itself when leaving the anesthesia.

If we combine ethanol, acetic acid or ammonia with xylocaine, it may have the capacity to help as an anesthetic in those affected in jellyfish stings and also avoid the discharge of more nematocysts.

Drinking lidocaine can help with the pain of gastritis .

Insensitivity:

The relative insensitivity to lidocaine is genetic.

In hypokalemic sensory overstimulation, a relative insensitivity to lidocaine has been described in people who also have attention deficit hyperactivity disorder.

In dental anesthesia, a relative insensitivity to lidocaine can occur for anatomical reasons due to unexpected nerve positions.

Some people with Ehlers-Danlos syndrome are insensitive to xylocaine.

Veterinary use:

It is a component of the veterinary drug Tributame along with embutramide and chloroquine used to carry out euthanasia in horses and dogs.

Presentations

Xylocaine is available in various forms, which include:

  • Solution for injection at 1, 2 and 5%.
  • Hyperbaric injectable solution at 5%.
  • 4% cream
  • Adhesive dressing at 5%.
  • 10% aerosol.
  • Gel bucal.

Adverse effects

Side effects on this medication are very rare when used as a local anesthetic.

Most adverse reactions associated with lidocaine for anesthesia are related to the administration technique (resulting in systemic exposure) or the pharmacological effects of anesthesia, and allergic reactions rarely occur.

There are effects that can occur in the central nervous system (CNS) and cardiovascular, if the patient is subjected to excessive amounts of xylocaine for a long time.

Effects in the CNS can occur due to lower plasma concentrations and in higher concentrations cardiovascular effects can occur, however in low concentrations cardiovascular collapse can also occur.

Adverse reactions by system are:

  • Excitation of the central nervous system: tremor, tingling around the mouth, nervousness, agitation, euphoria, anxiety, apprehension, hallucinations, headache, hyperesthesia , dizziness, seizures, pupillary changes and psychosis.
  • Depression of the central nervous system: respiratory depression, apnea , lethargy, speech difficulty, hypesthesia, disorientation, confusion, drowsiness, and loss of consciousness.
  • Cardiovascular: edema, redness, hypotension , cardiac arrest, arrhythmias, bricardia , venous insufficiency and increase of the defibrillator threshold.
  • Respiratory: respiratory depression, dyspnea and bronchospasm .
  • Gastrointestinal: vomiting, nausea and metallic taste.
  • Ears: tinnitus.
  • Eyes: local burning, conjunctival hyperemia , changes or ulceration of the corneal epithelium, diplopia, visual changes.
  • Skin: bruising, skin rash, skin irritation when applied topically, itching, swelling of the vein at the site of injection, depigmentation, edema, hives , and angioedema .
  • Sangre: metahemoglobinemia.
  • Allergy.

The adverse reactions associated with the use of intravenous xylocaine are similar to the toxic effects of previous systemic exposure.

These are related to the dose and are more frequent at high infusion rates (≥3 mg / min).

In general, it is safe to use xylocaine with a vasoconstrictor such as epinephrine , even in regions such as the nose, ears, fingers and toes.

While concerns about tissue death if used in these areas have been raised, the evidence does not support these concerns.

Interactions

Pharmacological interactions:

The administration of local anesthetic solutions containing epinephrine or norepinephrine to patients receiving monoamine oxidase inhibitors or tricyclic antidepressants can cause severe and prolonged hypertension.

Phenothiazines and butyrophenones can reduce or reverse the pressor effect of epinephrine.

The concurrent use of these agents should generally be avoided.

In situations where concurrent therapy is necessary, careful monitoring of the patient is essential.

The administration of vasopressor drugs (for the treatment of hypotension related to obstetric blockages) and oxytocic drugs can cause severe persistent hypertension or cerebrovascular accidents.

Drug / laboratory test interactions:

Intramuscular injection of lidocaine may result in an increase in creatine phosphokinase levels.

Therefore, the use of this enzyme, without separation of isoenzymes, as a diagnostic test for the presence of acute myocardial infarction can be compromised by the intramuscular injection of lidocaine.

Contraindications

Absolute contraindications to the use of xylocaine include:

  • Heart block:  second or third degree (without pacemaker).
  • Adams-Stokes syndrome.
  • Severe sinoatrial block (without pacemaker).
  • Severe adverse reaction to the drug to local anesthetics with lidocaine or amide.
  • Concurrent treatment with quinidine, flecainide, disopyramide, procainamide (class I antiarrhythmic agents).
  • Previous use of amiodarone hydrochloride.
  • This product is not recommended to treat tooth pain in infants.
  • Síndrome de Wolff-Parkinson-White.

Be cautious in patients with any of these:

  • Hypotension not due to arrhythmia.
  • Bradicardia.
  • Accelerated idioventricular rhythm.
  • Elderly patients
  • Deficiency of pseudocholinesterase.
  • Intra-articular infusion (this is not an approved indication and may cause chondrolysis).
  • Porphyria , especially acute intermittent porphyria.
  • Impaired liver function: people with decreased liver function may have an adverse reaction with repeated administration of lidocaine because the drug is metabolized in the liver.

Xylocaine has been classified as porphyrinogenic due to the hepatic enzymes that it induces, although clinical evidence suggests that it is not.

Bupivacaine is a safe alternative in this case.

Overdose

Overdoses with xylocaine can be the result of excessive administration by:

  • Topical or parenteral route.
  • Accidental oral intake of topical preparations by children who are more susceptible to an overdose.
  • Accidental intravenous injection (instead of subcutaneous, intrathecal or paracervical).
  • Prolonged use of subcutaneous medications such as infiltrating anesthesia during cosmetic surgical procedures.

These occurrences have often led to severe toxicity or death in both children and adults.

Xylocaine and its two main metabolites can be quantified in blood, plasma or serum to confirm the diagnosis in possible victims of poisoning or to help in the forensic investigation in case of fatal overdose.

It is important in the interpretation of analytical results to recognize that xylocaine is often routinely administered intravenously as an antiarrhythmic agent in critical situations of cardiac care.

Treatment with intravenous lipid emulsions (used for parental feeding) to reverse the effects of local anesthetic toxicity is becoming more common than it was in the past.

Xylocaine in large quantities can be toxic to cartilage, and intra-articular infusions can lead to postartroscopic glenohumeral chondrolysis.