Lidocaine is a Western medicine. It is commonly used in the form of a plaster. It is an amide drug. It is used to relieve postherpetic neuralgia and is used on unbroken skin.
Element
The main ingredient of this product is lidocaine.
Characteristics
Lidocaine Gel Patch: A gel patch in which the paste is evenly applied on a backing and covered with a thin film. The paste is white to light yellow.
Indications
This product is used to relieve postherpetic neuralgia and is used on unbroken skin.
Specification
Lidocaine gel patch: Each patch (14.0cm×10.0cm) contains 14g of patch and 700mg of lidocaine.
Dosage
The usage and dosage of this product in different dosage forms and specifications may vary. Please read the specific drug instructions for use, or follow the doctor’s advice.
Lidocaine gel patch:
1. This product is used on undamaged skin, covering the area with the most severe pain. Apply according to the prescribed amount (up to 3 patches at a time), and the cumulative application time within 24 hours shall not exceed 12 hours.
2. Patients can cut the product into small pieces with scissors before removing the plastic film according to the area of pain. It is recommended to reduce the area of use for weak patients or patients with liver and kidney dysfunction.
3. If the patient experiences unbearable irritation or burning sensation during use, the drug can be removed and used again after the irritation subsides.
4. When this product is used in combination with preparations containing local anesthetics, the total absorption of all preparations must be considered.
Adverse Reactions
1. Systemic (dose-related) reactions: When this product is used properly, the possibility of systemic reactions is low due to the small absorbed dose. Lidocaine systemic reactions are essentially similar to other amide local anesthetics, including central nervous system excitation and/or inhibition (sleepiness, paresthesia, convulsions, coma, and respiratory depression, etc.). Among them, the reaction of central nervous system excitation may be short-lived or not occur. In this case, it may first manifest as drowsiness or coma. Cardiovascular manifestations may include bradycardia, hypotension, and cardiac arrest caused by cardiovascular failure.
2. Local drug reaction: During or after use of this product, the skin may immediately produce irritation, itching, local paresthesia, discoloration, decolorization, burning sensation, dermatitis, erythema, papules, blisters, bruises, edema, peeling, or petechiae at the site of application. These symptoms are usually mild, short-lived, and transient, and will naturally subside within a few minutes or hours.
3. Allergic reaction: Lidocaine may cause allergic or allergic-like reactions, but the possibility of occurrence is extremely low. Its characteristics are: angioedema, bronchospasm, dermatitis, dyspnea, allergy, laryngeal spasm, itching, shock and urticaria. If the above symptoms occur, relevant measures should be taken. The results of skin sensitivity test are not suitable for the prediction of allergic adverse reactions to this product.
Taboo
This product is contraindicated in patients with a history of allergy to amide local anesthetics or to other ingredients in this product.
Precautions
1. Accidental contact with children: Used products still contain a large amount of lidocaine. Although this risk has not been evaluated so far, children or pets may have serious adverse reactions if they chew or swallow new or used products. This product should be properly stored and handled to ensure that children, pets or other people cannot come into contact with it.
2. Use with caution:
(1) Patients with severe liver disease: Because their liver cannot metabolize lidocaine normally, they are at greater risk of lidocaine poisoning.
(2) For patients who are allergic to para-aminobenzoic acid derivatives (procaine, benzocaine, etc.), no cross-allergy was found after using lidocaine. However, patients with a history of drug allergy should use this product with caution, especially those who are uncertain about the allergen.
3. Notes on use:
(1) Broken skin: Although not tested, administration to broken or inflamed skin may result in increased absorption of lidocaine and increased blood concentration. This product is only for use on unbroken skin.
(2) External heat source: It is not recommended to place an external heat source such as a hot pad or electric blanket on top of lidocaine gel. Although these situations have not been studied, they may increase blood drug concentrations.
(3) Eye contact: Although there is no relevant research, based on the severe eye irritation caused by similar preparations in animals, eye contact with this product should be avoided. If the eyes come into contact with this product, they should be immediately rinsed with plenty of water or saline to protect the eyes until the sensation is restored.
(4) Wash your hands after contact with this product. Avoid contact with eyes before washing your hands. Use this product immediately after taking it out of the packaging bag. Do not store this product outside the sealed packaging bag. Fold the sticky paste side of the used product (so that the sticky paste sides will stick to each other automatically) and discard it to keep it out of reach of children and pets.
(5) This product will lose its stickiness when it gets wet. Avoid contact with water, such as bathing or swimming.
4. Use by pregnant and lactating women:
(1) Pregnant women: No studies have been conducted on the use of this product in pregnant women. Studies on the reproductive effects of lidocaine were conducted in rats, and no damage to the fetus was found when lidocaine was administered subcutaneously at a dose of 30 mg/kg. However, no adequate and well-controlled studies have been conducted in pregnant women. Because the results of animal reproductive studies cannot predict human responses, it should only be used when the benefits of treatment outweigh the risks.
(2) Delivery: No studies have been conducted on the use of this product during delivery. Lidocaine has no contraindications during delivery. If this product is used in combination with other drugs containing lidocaine, the total dose of all preparations should be considered.
(3) Lactating women: No studies have been conducted on the use of this product in lactating women. Lidocaine can be distributed into breast milk, and the breast milk/plasma drug ratio is 0.4. This product should be used with caution in lactating women.
5. Use in children: The effectiveness and safety of this drug for children have not yet been established.
6. Use in the elderly: Pay attention to the physical condition of the elderly patients and the skin condition of the application area, refer to [Usage and Dosage].
7. Drug overdose:
(1) Overdose caused by lidocaine absorption through the skin is rare. When the drug administration area or application time exceeds the prescribed dosage, it may lead to excessive absorption of lidocaine, increased blood drug concentration, and thus serious adverse reactions (see [Adverse Reactions]).
(2) Lidocaine will be toxic when its blood concentration is higher than 5μg/ml. The blood concentration of lidocaine is determined by systemic absorption and clearance rate. Long-term use, use of more than the prescribed dose, use in younger patients or patients with liver and kidney dysfunction will lead to increased lidocaine blood concentration. When this product is used at the prescribed dose, the average peak blood concentration is 0.13μg/ml, but in some individuals it is higher than 0.25μg/ml.
(3) In the absence of local large-scale use of this product or excessive oral lidocaine administration, the evaluation of toxic symptoms should consider other causes, either from lidocaine administered by other routes, or from excessive doses of other local anesthetics.
(4) When lidocaine was orally administered to non-fasted female rats, the LD50 was 459 (346-773) mg/kg (calculated as hydrochloride), while when lidocaine was orally administered to fasted female rats, the LD50 was 214 (159-324) mg/kg (calculated as hydrochloride), which is equivalent to a human dose of 4000 mg and 2000 mg (60-70 kg) respectively based on body surface area conversion.
(5) When lidocaine overdose is suspected, blood drug concentration should be checked. Treatment of drug overdose includes close monitoring, supportive treatment, and symptomatic treatment. Dialysis is not recommended for the treatment of acute lidocaine overdose.
Drug interactions
1. Antiarrhythmic drugs: Patients taking class I antiarrhythmic drugs (such as tocainide, mexiletine) should use this product with caution because the toxic effects may be additive or synergistic.
2. Local anesthetics: When this product is used in combination with other drugs containing local anesthetic ingredients, the total absorption of all preparations should be considered.
Pharmacological Action
1. Lidocaine is an amide local anesthetic that stabilizes nerve cell membranes and blocks nerve excitation and conduction by inhibiting the sodium ion channels of nerve cell membranes.
2. After administration of this product, lidocaine enters the intact skin and can produce analgesic effects but is not sufficient to produce complete nerve block.
Toxicological effects
1. Genotoxicity: In the microsomal metabolic activation system, lidocaine hydrochloride had no mutagenic effect on Salmonella/mammalian cells, and no chromosomal aberration effect was observed in the human lymphocyte chromosome aberration test and the mouse micronucleus test.
2. Reproductive toxicity: No harm was observed to the fetus when lidocaine was administered subcutaneously to rats at a dose of 30 mg/kg.
3. Carcinogenicity: A small amount of the metabolite xylidine was found to be carcinogenic in rats. After using this product, the blood concentration of this metabolite is negligible.
Pharmacokinetics
1. Absorption:
(1) The systemic absorption of lidocaine in this product is directly related to the duration of application and the contact area. In a pharmacokinetic study, three patches of this product were applied to the intact skin on the backs of healthy volunteers, with an application area of 420 cm2 [Maxy6], and the application time was 12 hours. During the application period and 12 hours after the removal of this product, blood samples were collected to measure the lidocaine concentration.
(2) Absorption of lidocaine: 3 patches (2100 mg) of this product were applied to the back with an area of 420 cm2. The absorbed dose C max was 0.13±0.06 μg/ml and T max was 11 hr.
(3) When administered according to the prescribed dosage, only 3±2% of the lidocaine in this product can be absorbed. At least 95% (665 mg) of the lidocaine remains in the used product. The average peak concentration of lidocaine in the blood is 0.13 μg/ml (approximately 1/10 of the concentration required to treat arrhythmias). 3 patches of this product were used simultaneously, with a duration of 12 hours (maximum recommended daily dose), once a day for a total of three days, indicating that the lidocaine blood concentration does not increase with daily administration.
2. Distribution: After intravenous administration of lidocaine to healthy volunteers, the distribution volume was 0.7-2.7L/kg (average 1.5±0.6SD, n=15). At the blood drug concentration produced by the use of this product, about 70% of lidocaine is bound to plasma proteins, mainly to α-1-acid glycoprotein. At higher plasma concentrations (containing 1-4μg/mL free lidocaine), the binding of lidocaine to plasma proteins is concentration-dependent. Lidocaine may cross the placenta and blood-brain barrier by passive diffusion.
3. Metabolism: It is not clear whether lidocaine can be metabolized in the skin. Lidocaine can be rapidly metabolized into a variety of metabolites in the liver, including monoethylglycine xylidine (MEGX) and glycine xylidine (GX), which have pharmacological effects similar to lidocaine but are less active than lidocaine. The pharmacological effects of the trace metabolite 2,6-dimethylaniline are unknown, but it has been found to be carcinogenic in rats. After administration of this product, the blood concentration of 2,6-dimethylaniline is very low and can be ignored. After intravenous administration, the concentrations of MEGX and GX in serum are 11-36% and 5-11% of the lidocaine concentration, respectively.
4. Excretion: Lidocaine and its metabolites are excreted by the kidneys. Less than 10% of lidocaine is excreted in its original form. When administered intravenously, the plasma elimination half-life of lidocaine is 81-149 minutes (average 107±22SD; n=15). The systemic clearance rate is 0.33-0.90L/min (average 0.64±0.18SD, n=15).
Storage method
Keep in a dark place and store in a sealed container at a temperature not exceeding 30℃.
Validity
36 months
Implementation Standards
Lidocaine gel patch: National Food and Drug Administration National Drug Standard YBH01302018.