Active Ingredients

Lidocaine – Effect, Application & Risks

Lidocaine

Lidocaine is a drug from the class of local anesthetics that also acts as an antiarrhythmic . It belongs to the group of sodium channel blockers.

What is lidocaine?

The drug lidocaine was the first amino-amide local anesthetic. It was synthesized by Swedish chemists Bengt Lundqvist and Nils Löfgren in 1943. They sold their patent rights to the pharmaceutical company Astra AB.

Lidocaine is based on 2,6-xylidine. Lidocaine is produced from this in several synthesis stages. The drug is available as a single preparation or as a combination preparation in the form of gels, pastes, ointments, suppositories and injection solutions. Injection solutions can be 0.25% or 5%.

Lidocaine belongs to the local anesthetics class of sodium channel blockers. However, it is used not only as a local anesthetic, but also as an antiarrhythmic in medicine. Lidocaine works very quickly. It is metabolized in what is called the cytochrome 450 system of the liver . The bioavailability is very good. Less than 10 percent of the original dose is excreted in the urine .

Pharmacological action

Lidocaine is a sodium channel blocker. The drug blocks the voltage-gated channels for sodium . These are located in the cell membranes of nerve cells . When a nerve cell is excited, sodium rushes into the cells . An action potential is created and the excitation is passed on by depolarization processes from one nerve cell to the next or from one nerve cell to the target cell.

When the skin’s sensitive receptors perceive sensations such as pressure, pain, heat or cold, they transmit these sensations to the brain . This requires excitation transmission and thus an opening of the sodium channels in the cell membranes. Lidocaine blocks the sodium channels, preventing sodium from entering the cells. The emergence of an action potential is made more difficult, the stimulus is not passed on.

Lidocaine has only a local effect. Only the nerve cells located at the site of application of the drug are affected. Thin nerve fibers are blocked more quickly in their transmission function than thick nerve fibers. After the application, the pain sensation is initially limited. Temperatures are then no longer perceived. Then the touch and pressure perceptions deteriorate . Eventually the efferents drop out. Efferents are nerve fibers that go from the central nervous system to the muscles . If the efferents fail, the motor function in the affected area also fails.

Medical Application & Use

The main field of application of lidocaine is regional anesthesia. Local anesthesia eliminates the sensation of pain in a limited area of ​​the body. The advantage over general anesthesia is that lung and brain function , metabolism and the acid-base balance are hardly affected.

As a local anesthetic, lidocaine is often administered during dental and medical treatment. It is used for topical anesthesia, conduction anesthesia and infiltration anesthesia. In infiltration anesthesia, lidocaine is injected into the tissue to numb a small area. This may be necessary, for example, when suturing a laceration or similar small interventions. Alternatively, lidocaine can be injected near a nerve . This numbs the supply area of ​​the nerve. This process is also known as block anesthesia. After an exposure time of one to three minutes, the local anesthetic lasts one to three hours.

Lidocaine is also well absorbed through the mucous membranes . The active substance is therefore used for surface anesthesia in the form of sprays or ointments. Topical anesthesia guarantees freedom from pain, for example in the treatment of haemorrhoids or in endoscopies .

Lidocaine is also available in the form of so-called delay creams or delay sprays. These are applied thinly to the glans of the penis with the foreskin pulled back to suppress premature ejaculation . Lidocaine is also used as a local anesthetic as an active ingredient in teething aids.

The second major area of ​​application for the drug is cardiac arrhythmias . Lidocaine slows the spread of impulses in the heart’s conduction system . The drug thus has a stabilizing effect on the heart rhythm and suppresses cardiac arrhythmias that originate in the heart chambers . Thus, lidocaine is mainly used for the treatment of tachycardic cardiac arrhythmias. In the past, lidocaine was used very frequently as an emergency medication. However, its use has since declined because lidocaine not only prevents cardiac arrhythmias, but can also produce them in some cases.

In its function as an antiarrhythmic, lidocaine must be administered intravenously. Indications for the intravenous administration of lidocaine are cardiac arrhythmias of any origin. This also includes cardiac arrhythmias caused by poisoning with antidepressants or cardiac glycosides . Lidocaine can be administered preventively before procedures that can irritate the heart muscle. It reduces the risk of ventricular arrhythmias.

Risks & side effects

Side effects are rare with low doses of lidocaine. If the dosage is too high, cardiac and systemic side effects can occur. These include symptoms such as lightheadedness , agitation, convulsions , and a negative inotropy of the heart. With negative inotropy, the force of contraction of the heart is reduced. In individual cases, it can also lead to a drop in blood pressure or allergic reactions. Very rarely, patients fall into a coma after high doses of lidocaine .

Lisa Newlon
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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.