What Is Xyliderm (Lidocaine) 5% Patch
Xyliderm (Lidocaine) 5% patch (Lidoderm) is a prescription medication used to relieve nerve pain caused by a shingles infection, also called postherpetic neuralgia (PHN). It is a local anesthetic that helps lessen pain by numbing your nerves. The patch can be worn for up to 12 hours in a 24-hour period after being applied directly to the uncomfortable area of your skin once a day. Temporary skin irritation, redness, and a little burning feeling where the patch is applied are typical side effects.
CLINICAL PHARMACOLOGY
Pharmacodynamics
By blocking the ionic fluxes necessary for impulse initiation and conduction, lidocaine, an amide-type local anesthetic, is thought to stabilize neuronal membranes.
After applying a lidocaine patch, the amount of lidocaine that penetrates intact skin is enough to cause an analgesic effect, but not enough to cause a full sensory block.
Pharmacokinetics
Absorption
The length of application and the surface area covered by the 5% lidocaine patch have a direct impact on the amount of lidocaine that is systemically absorbed. Three lidocaine patches were put to 420 cm 2 of undamaged skin on the back of healthy volunteers for 12 hours as part of a pharmacokinetic investigation. Blood samples were taken during the application and 12 hours after the patches were removed in order to measure the concentration of Xyliderm (lidocaine). Table 1 provides a summary of the findings.
It is anticipated that only 3 ± 2% of the administered dose will be absorbed when LIDOCAN is used in accordance with the approved dosing guidelines. A utilized patch will contain at least 95% (665 mg) of lidocaine. About 1/10 of the therapeutic quantity needed to treat cardiac arrhythmias, or 0.13 mcg/mL, is the average peak blood concentration of lidocaine. The lidocaine concentration did not rise with daily usage, according to repeated application of three patches concurrently for 12 hours (the recommended maximum daily dose), once daily for three days. Figure 1 displays the mean plasma pharmacokinetic profile for the fifteen healthy individuals.
Distribution
When healthy volunteers receive intravenous lidocaine, the volume of distribution ranges from 0.7 to 2.7 L/kg (mean 1.5 ± 0.6 SD, n = 15). About 70% of lidocaine is bound to plasma proteins, mostly alpha-1-acid glycoprotein, at quantities generated by applying a 5% lidocaine patch. The plasma protein binding of lidocaine is concentration dependent at significantly higher plasma concentrations (1 to 4 mcg/mL of free base). Presumably through passive diffusion, lidocaine passes through the blood-brain and placental barriers.
Metabolism
The skin’s ability to metabolize lidocaine is unknown. The liver quickly breaks down lidocaine into many metabolites, such as glycinexylidide (GX) and monoethylglycinexylidide (MEGX), both of which have pharmacologic activity that is comparable to but less effective than lidocaine. 2,6-xylidine is a minor metabolite that causes cancer in rats but has no recognized pharmacologic effect. After applying a 5% lidocaine patch, there is very little of this metabolite in the blood. MEGX and GX concentrations in serum range from 11 to 36% and 5 to 11% of lidocaine concentrations, respectively, after intravenous treatment.
Excretion
The kidneys eliminate lidocaine and its metabolites. Less than 10% of lidocaine is eliminated unaltered. After IV injection, lidocaine is eliminated from plasma during a half-life of 81 to 149 minutes (mean 107 ± 22 SD, n = 15). Systemic clearance ranges from 0.33 to 0.90 L/min (mean 0.64 ± 0.18 SD, n = 15).
INDICATION AND USAGE
Post-herpetic neuralgia pain can be relieved with Xyliderm (Lidocan). Only intact skin should be treated with it.
CONTRAINDICATIONS
Patients who have a history of sensitivity to amide-type local anesthetics or any other ingredient in the product should not use Xyliderm (Lidocan).
WARNINGS
Risk of Methemoglobinemia
Methemoglobinemia cases have been linked to the use of local anesthetics. Methemoglobinemia can occur in any patient, but it is more likely to manifest clinically in those with glucose-6-phosphate dehydrogenase deficiency, congenital or idiopathic methemoglobinemia, cardiac or pulmonary compromise, infants younger than six months, and concurrent exposure to oxidizing agents or their metabolites. It is advised to closely monitor these individuals for symptoms and indicators of methemoglobinemia if local anesthetics must be administered.
Methemoglobinemia symptoms, which include cyanotic skin coloring and/or aberrant blood coloration, might appear right away or a few hours after exposure. In order to prevent more severe adverse effects on the central nervous system and cardiovascular system, such as seizures, coma, arrhythmias, and death, prompt treatment is necessary because methemoglobin levels may continue to grow. Stop using any oxidizing agents, including Lidocan. Patients may react to supportive care, such as oxygen therapy or hydration, depending on how severe their symptoms are. Treatment with methylene blue, exchange transfusions, or hyperbaric oxygen may be necessary for a more severe clinical presentation.
Accidental Exposure in Children
There is a significant amount of Xyliderm (lidocaine) (at least 665 mg) in even a utilized 5% lidocaine patch. Although the danger associated with this formulation has not been assessed, chewing or eating a fresh or old lidocaine patch 5% could have major negative effects on a young kid or pet. Lidocan should be stored and disposed of by patients away from children, pets, and other people (see HANDLING AND DISPOSAL).
Overdosing
Applying Lidocan to bigger areas or for a longer period of time than is advised could result in higher absorption of lidocaine and high blood concentrations, which could cause major side effects (see ADVERSE REACTIONS, Systemic Reactions). When lidocaine blood concentrations exceed 5 mcg/mL, lidocaine toxicity may be anticipated. The rate of systemic absorption and excretion of lidocaine determines its blood concentration. The blood concentration of lidocaine may rise as a result of longer application times, applying more patches than is advised, smaller patients, or poor elimination. The average peak blood concentration of Lidocan at the authorized dosage is approximately 0.13 mcg/mL, while some people have shown values more than 0.25 mcg/mL.
PRECAUTIONS
General
Hepatic Disease: Because they are unable to properly metabolize Xyliderm (lidocaine), patients with severe hepatic disease are more likely to experience dangerous blood concentrations of the drug.
Allergic Reactions: Individuals who are allergic to derivatives of para-aminobenzoic acid (procaine, tetracaine, benzocaine, etc.) have not demonstrated cross-sensitivity to lidocaine. However, individuals with a history of medication sensitivity should use LIDOCAN cautiously, particularly if the causative agent is unknown.
Non-intact Skin: Although it hasn’t been studied, applying lidocaine to broken or irritated skin may boost blood concentrations due to enhanced absorption. It is only advised to use LIDOCAN on undamaged skin.
External Heat Sources: Since this has not been tested and may raise plasma lidocaine levels, it is not advised to place external heat sources, such as heating pads or electric blankets, over lidocaine patch 5%.
Eye Exposure: Despite the lack of research, LIDOCAN should not come into contact with the eyes because identical products have been shown to cause significant eye irritation in animals. If there is eye contact, clean the eye right away with saline or water and shield it until feeling returns.
Drug Interactions
Antiarrhythmic Drugs
Because the harmful effects of LIDOCAN are cumulative and possibly synergistic, it should be used cautiously in patients on Class I antiarrhythmic medications (such as mexiletine and tocainide).
Local Anesthetics: The amount absorbed from all formulations must be taken into account when LIDOCAN is administered concurrently with other medications that contain local anesthetic ingredients.
Carcinogenesis, Mutagenesis, Impairment of Fertility
Carcinogenesis: A minor metabolite, 2,6-xylidine, has been found to be carcinogenic in rats. The blood concentration of this metabolite is negligible following application of Lidocan™.
Mutagenesis: Lidocaine HCl is not mutagenic in Salmonella/mammalian microsome test nor clastogenic in chromosome aberration assay with human lymphocytes and mouse micronucleus test.
Impairment of Fertility: The effect of LIDOCAINE on fertility has not been studied.
Pregnancy
Teratogenic Effects
Pregnancy has not been explored with xyliderm (lidocaine). Lidocaine has been administered subcutaneously to rats at levels up to 30 mg/kg in reproduction studies, and no evidence of fetal damage has been found. However, there aren’t any sufficient, carefully monitored trials including expectant mothers. Xyliderm (Lidocaine) should only be used during pregnancy if absolutely necessary because research on animal reproduction is not necessarily indicative of human response.
Labor and Delivery
There is no research on xyliderm (lidocaine) in labor and delivery. During labor and delivery, lidocaine is not contraindicated. The total dosages contributed by all formulations must be taken into account if xyliderm (lidocaine) is used in conjunction with other lidocaine-containing medicines.
Nursing Mothers
There is no research on this medication in breastfeeding moms. Human milk contains lidocaine, which has a milk:plasma ratio of 0.4. When giving Lidocan to a breastfeeding mother, care should be taken.
ADVERSE REACTIONS
Application Site Reactions
Blisters, bruising, burning sensation, depigmentation, dermatitis, discoloration, edema, erythema, exfoliation, irritation, papules, petechia, pruritus, vesicles, or abnormal sensation may develop on the skin at the application site during or right after Lidocan treatment. Usually moderate and brief, these reactions go away on their own in a matter of minutes to hours.
Allergic Reactions
Although they are uncommon, lidocaine-related allergic and anaphylactoid responses might happen. Angioedema, bronchospasm, dermatitis, dyspnea, hypersensitivity, laryngospasm, pruritus, shock, and urticaria are their hallmarks. If they do arise, traditional methods should be used to handle them. The value of using skin testing to detect sensitivity is questionable.
Systemic (Dose-Related) Reactions
Because of the minimal amount absorbed, systemic adverse events are uncommon after using Xyliderm (Lidocan) appropriately (see CLINICAL PHARMACOLOGY, Pharmacokinetics). Lidocaine’s systemic side effects, such as CNS excitation and/or depression (lightheadedness, nervousness, apprehension, euphoria, confusion, dizziness, drowsiness, tinnitus, blurred or double vision, vomiting, sensations of heat, cold, or numbness, twitching, tremors, convulsions, unconsciousness, respiratory depression, and arrest), are comparable to those seen with other amide local anesthetics. Drowsiness that blends into unconsciousness may be the initial sign of excitatory CNS effects, which can be fleeting or nonexistent. Bradycardia, hypotension, and cardiovascular collapse that results in arrest are examples of cardiovascular manifestations.
OVERDOSING
Although it is uncommon, lidocaine overdose from cutaneous absorption is possible. Drug blood concentration should be measured if there is any indication of a lidocaine overdose (see ADVERSE REACTIONS, Systemic Reactions). Close observation, supportive care, and symptomatic therapy are all part of overdose management. When treating an acute lidocaine overdose, dialysis is of very little use.
When evaluating toxicity symptoms in the absence of significant topical overdose or oral intake, possible etiologies for the clinical consequences or overdosage from other sources of lidocaine or other local anesthetics should be taken into account.
The oral LD 50 of lidocaine HCl is 459 (346 to 773) mg/kg (as the salt) in non-fasted female rats and 214 (159 to 324) mg/kg (as the salt) in fasted female rats, which are equivalent to roughly 4000 mg and 2000 mg, respectively, in a 60 to 70 kg man based on the equivalent surface area dosage conversion factors between species.
DOSAGE AND ADMINISTRATION
Cover the most painful area of undamaged skin with LIDOCAN. Within a 24-hour period, apply the recommended number of patches (up to 3) just once for a maximum of 12 hours. Before removing the release liner, patches can be cut into smaller sizes with scissors. Refer to HANDLING AND DISPOSAL. It is possible to cover the application area with clothing. When a patient is incapacitated or has poor elimination, smaller treatment areas are advised.
Remove the patch or patches if you experience burning or irritation during application, and wait to reapply until the irritation goes away.
HANDLING AND DISPOSAL
After touching a 5% lidocaine patch, hands should be cleaned, and eye contact should be avoided. Patches should not be kept outside of their enclosed envelope. After removing from the protective envelope, apply right away. Used patches or parts of cut patches should be carefully disposed of where kids and pets cannot reach them. Fold used patches so that the sticky side stays to itself. Children should not be able to access 5% lidocaine patches.
