Lidocaine belongs to the group of medicines called local anesthetics and it is currently the most widely used one. Topical application of lidocaine causes reversible loss of sensory perception, especially of pain in a restricted area of the body. It blocks generation and conduction of nerve impulse at any part of the neuron with which it come in contact, without causing any structural damage. As a result no pain sensation takes place.
Lidocaine is generally used to alleviate pain and itching or other discomfort caused by certain clinical conditions such as sunburn or other minor burns, sore throat, minor cuts and scratches, poison oak, poison ivy, insect bites or stings and many other sources of skin irritations on the body surface. Lidocaine topical jelly or ointment is used on different body parts to cause numbness prior certain medical procedures. Lidocaine skin patch is also used to relieve pain caused by shingles.
This drug is available in the following dosage forms only with your doctor’s prescription:
If you are about to start a drug therapy, the risk-benefit ratio of taking the drug should be considered carefully. Here, the suitable drug therapy is chosen with active participation of both the doctor and the patient. There are some important factors such as drug interactions, metabolic impairment, hypersensitivity reaction, pregnancy, lactation etc. which may alter the desired therapeutic effects of such medications.
Sometimes the presence of other health disorders affects the beneficial effects of this medicine and even may cause serious toxic effects. If you have had any allergic reactions to any medicine, you must inform your doctor about that.
Further, make sure you mention your doctor
if you have any other health problems or medical disorders, especially infection, large sores, broken skin, or severe injury at the area of application.
Such local anesthetics like lidocaine often fail to afford adequate pain control in inflamed tissues because of the following reasons:
Blood flow to the inflamed area is increased, that’s why local anesthetic is removed more rapidly from the site.
Inflammation lowers the pH of the affected tissues which inactivate greater fraction of such medications as it is in the ionized form hindering diffusion into the axolemma.
Certain inflammatory products produced by the cells often oppose the anesthetic action of such medications.
In addition, certain drugs should not be used simultaneously along with such medications. For example, concurrent use of vasoconstrictors (e.g. adrenaline) prolongs the duration of action of lidocaine by decreasing their rate of removal from the local site, which increases the chances of subsequent local tissue edema and necrosis as well as delays wound healing by reducing oxygen supply and enhancing oxygen consumption in the affected area.
Additionally, it may raise blood pressure and promote arrhythmia in susceptible individuals. Thus, it is always advised to consult with your doctor if you are in need of some other medications or even any over-the-counter medicine for another health problem.
However, studies performed with such medications in pregnant and lactating women have failed to demonstrate a risk to the fetus and the nursing baby respectively. Thus, this medicine can be used during pregnancy and lactation if clearly needed.
The dosage schedule and the duration of drug therapy depend on the particular medical problem for which you are using this medicine. The therapeutic dose may also vary with patient’s condition or requirement and the strength of the medicine as well. Thus, you should use this medicine following the directions given by your doctor.
In order to treat pain and itching caused by minor skin problems, an adult should be treated with application of such medications over the affected area for 2 to 3 times in a day. The frequency of application may be increased up to 5 times a day if required. Children should be treated with great care and the dose should be determined by a healthcare professional. Moreover, the use of such medications is not suitable for those children who are below the age of 2 years.
If you miss any dose of this medicine, you should take it as soon as possible. But if it is time for your next dose, then you should skip the missed dose and go back to your regular treatment schedule.
Further, it is advised to store the medicine in a closed container at room temperature away from heat, moisture, and direct light. All kinds of medicines should be kept out of the reach of children as well as outdated medicines should be disposed by an appropriate way.
4 Precautions to Take
Firstly, regular visits to your doctor are recommended to check that this medicine is working properly or not. It is advised to wash your hands with soap and water before and after using this medicine. You should not apply this medicine over the area of open wounds, burns, or inflamed skin.
Further, you should stop using this medicine and check with your doctor immediately if your condition does not improve within a week, or if you have developed rashes, stinging, swelling, or irritation over the skin following application of such medications.
In addition, the following guidelines should be followed while you are using such medications:
Beta-blockers like propranolol should not be used concurrently along with local anesthetics (e.g. lidocaine) because they may minimize the effectiveness of such anesthetics by reducing their metabolism.
Vasoconstrictors (e.g. adrenaline) containing local anesthetic should be avoided for patients with ischemic heart disease, cardiac arrhythmia, thyrotoxicosis, uncontrolled hypertension, and those receiving beta-blockers or tricyclic antidepressants.
Such medicines should be used cautiously in case of glucose-6-phosphodiesterase deficiency, methemoglobin reductase deficiency, and pyruvate-kinase deficiency.
5 Potential Side Effects
Although each drug comes with little or more side effects, but most of the time remain subtle. Sometimes you may need to consult with the doctor if you feel any discomfort like blurred vision, trembling or shaking of the limbs, chest pain or discomfort, feeling of irregular heart beat etc.
Usual side effects need no medical attention but in some conditions may demand emergency resolution as in unconsciousness or seizure. However, toxicity after topical application is influenced by the relative rates of absorption and metabolism.
You should seek medical help when the following problems become significant
Problems affecting central nervous system (CNS) are light-headedness, dizziness, sleepiness, auditory and visual disturbances, mental confusion, disorientation, shivering, involuntary movements, convulsions, CNS depression leading to respiratory arrest.
Neurotoxicity (sensory and motor deficits) has been reported in certain individuals affecting peripheral nervous system.
Cardiovascular toxicity of such local anesthetics is manifested as myocardial depression, vasodilatation, bradycardia, hypotension, cardiac arrhythmias and vascular collapse.
Methemoglobinemia may also take place which lowers the amount of oxygen in your blood stream excessively resulting in medical emergency.
Hypersensitivity reactions like rashes, angioedema, dermatitis, contact sensitization, asthma, and rarely anaphylaxis may occur.
Additionally, methylparaben is often added as a preservative in certain local anesthetic solutions which may cause serious allergic reactions.
Moreover, local anesthetics also reduce the release of acetylcholine from motor nerve endings. As a result, paralysis of the voluntary muscles supplied by that nerve may also occur but rarely.
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