We often hear that Lidocaine can be the solution to many problems. Now, what is it, what are its benefits and what are the contraindications and risks in its use. Here we tell you all the details.
What is lidocaine?
Lidocaine, also known as xylocaine and lignocaine, is a drug used to numb tissue in a specific area. 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 higher doses for numbness, to decrease bleeding, and to make the numbing effect last longer. When used as an injectable, it generally starts working in four minutes and lasts from half an hour to three hours. Lidocaine mixtures can also be applied directly to the skin or mucous membranes to numb the area.
Lidocaine was discovered in 1946 and went on sale in 1948. It is on the World Health Organization’s Essential Medicines List, the safest and most effective medicines needed in a health system. It is available as a generic drug and is not very expensive. The wholesale cost in the developing world in 2014 was $ 0.45 to $ 1.05 wholesale per 20 ml vial of medicine.
Side effects of Lidocaine
Common side effects with IV use include drowsiness, muscle spasms, confusion, vision changes, numbness, tingling, and vomiting. It can cause low blood pressure and an irregular heart rate. There is a concern that injecting it into a joint may cause problems with the cartilage. In general, it appears to be safe to use in pregnancy. A lower dose may be required in people with liver problems. It is generally safe to use in people who are allergic to tetracaine or benzocaine. Lidocaine is a class Ib antiarrhythmic medication. Lidocaine works by blocking sodium channels and therefore slowing the rate of contractions of the heart. When used locally as an anesthetic agent, local neurons cannot signal to the brain.
The efficacy profile of lidocaine as a local anesthetic is characterized by a rapid onset of action and an intermediate duration of efficacy. Therefore, lidocaine is suitable for infiltration, blockage, and superficial anesthesia. Longer-acting substances such as bupivacaine sometimes have a preference for spinal and epidural anesthesia; Lidocaine, however, has the advantage of a rapid onset of action. Epinephrine vasoconstricts the arteries, reducing bleeding and also delaying the reabsorption of lidocaine, nearly doubling the duration of anesthesia. For superficial anesthesia, various formulations can be used for endoscopies, before intubations, etc. Lidocaine’s pH buffering makes local numbness less painful.
Lidocaine drops can be used in the eyes for short ophthalmic procedures. There is tentative evidence for topical lidocaine for neuropathic pain and pain at the skin graft donor site. As a local anesthetic agent, it is used for the treatment of premature ejaculation.
Cardiac arrhythmia : Lidocaine is also the most important class 1b antiarrhythmic drug; is used intravenously for the treatment of ventricular arrhythmias (for acute myocardial infarction, digoxin poisoning, cardioversion, or cardiac catheterization) if amiodarone is not available or contraindicated. Lidocaine should be given for this indication after defibrillation, CPR, and vasopressors have been initiated. A routine preventive dose after myocardial infarction is no longer recommended as the overall benefit is not convincing.
Epilepsy : A 2013 review on the treatment of neonatal seizures recommended intravenous lidocaine as a second-line treatment, if phenobarbital does not stop the seizures.
Other Uses : Inhaled lidocaine can be used as a cough suppressant that acts peripherally to reduce the cough reflex. This application can be implemented as a safety and comfort measure for patients who need to be intubated, as it reduces the incidence of coughing and any tracheal damage it may cause when coming out of anesthesia.
Lidocaine, along with ethanol, ammonia, and acetic acid, can also help in the treatment of jellyfish stings, as they numb the affected area and prevent further discharge of nematocysts. For gastritis, drinking slimy lidocaine can help with pain.
Lidocaine, usually in the form of lidocaine hydrochloride, is available in a variety of forms, including many topical formulations and solutions for injection or infusion.
Adverse effects of lidocaine
Adverse drug reactions (ADRs) are rare when lidocaine is used as a local anesthetic and administered correctly. Most of the associated adverse reactions to anesthesia resulting in systemic exposure or the pharmacological effects of anesthesia, and allergic reactions only occur rarely. Systemic exposure to excessive amounts of lidocaine mainly causes central nervous system (CNS) and cardiovascular effects. Effects on the central nervous system usually occur at lower plasma concentrations and additional cardiovascular effects occur at higher concentrations, although cardiovascular collapse can also occur at low concentrations. The ADRs per system are:
- CNS overcapacity and stimulation: nervousness, agitation, anxiety, apprehension, tingling around the mouth (circumoral paresthesia), headache, hyperesthesia, tremor, dizziness, pupillary changes, psychosis, euphoria, hallucinations and seizures
- CNS depression with increasingly heavy exposure: drowsiness, lethargy, slurred speech, hypoaesthesia, confusion, disorientation, loss of consciousness, respiratory depression, and apnea.
- Cardiovascular: hypotension, bradycardia, arrhythmias, flushing, venous insufficiency, increased defibrillator threshold, edema and / or cardiac arrest, some of which may be due to hypoxemia secondary to respiratory depression.
- Respiratory: bronchospasm, dyspnea, respiratory depression or arrest
- Gastrointestinal: metallic taste, nausea, vomiting
- Ears: tinnitus
- Eyes: local burning, conjunctival hyperemia, corneal epithelium changes / ulceration, diplopia, visual changes (opacification)
- Skin: itching, depigmentation, rash, hives, edema, angioedema, bruising, swelling of the vein at the injection site, red and irritated skin when applied topically.
- Sangre: metahemoglobinemia
The adverse reactions associated with the use of intravenous lidocaine are similar to the toxic effects of previous systemic exposure. These are dose related and are more common at high infusion rates (≥3 mg / min). Common adverse reactions include: headache, dizziness, drowsiness, confusion, visual disturbances, tinnitus, tremor, and / or paraesthesia. Uncommon adverse reactions associated with the use of lidocaine include: hypotension, bradycardia, arrhythmias, cardiac arrest, muscle spasms, seizures, or respiratory depression.
- Heart block, second or third degree (without pacemaker)
- Very deep and severe sinoatrial block (no pacemaker)
- Serious adverse drug reaction to local anesthetics with lidocaine or amide
- Hypersensitivity to corn and corn-related products (corn-derived dextrose is used in mixed injections)
- Concurrent treatment with quinidine, flecainide, disopyramide, procainamide (class I antiarrhythmic agents)
- Previous use of amiodarone hydrochloride
- Adams-Stokes syndrome
- Wolff-Parkinson-White syndrome
- Counterproductive viscous lidocaine to counteract teething pain in children and babies.
Dr. Samantha Robson ( CRN: 0510146-5) is a nutritionist and website content reviewer related to her area of expertise. With a postgraduate degree in Nutrition from The University of Arizona, she is a specialist in Sports Nutrition from Oxford University and is also a member of the International Society of Sports Nutrition.