warnings and cautions
Warnings and Precautions Medicines intended to be applied to the skin should not be swallowed. Lidothol Gel is flammable. Keep away from open flame. You should never heat, microwave, or add the medicine to hot water. Risk of Methemoglobinemia Cases of methemoglobinemia have been reported in association with lidocaine use. Although all patients are at risk for methemoglobinemia, patients with glucose-6-phosphate dehydrogenase deficiency, congenital or idiopathic methemoglobinemia, cardiac or pulmonary compromise, infants under 6 months of age, and concurrent exposure to oxidizing agents or their metabolites are more susceptible to developing the condition. If lidocaine must be used in these patients, close monitoring for symptoms and signs of methemoglobinemia is recommended. Signs of methemoglobinemia may occur immediately or may be delayed some hours after exposure, and are characterized by a cyanotic skin discoloration and/or abnormal coloration of the blood. Methemoglobin levels may continue to rise; therefore, immediate treatment is required to avert more serious central nervous system and cardiovascular adverse effects, including seizures, coma, arrhythmias, and death. Excessive Dosing Excessive dosing by applying Lidothol Gel to larger areas could result in increased absorption of lidocaine and high blood concentrations, leading to serious adverse effects (see ADVERSE REACTIONS, Systemic Reactions). Lidocaine toxicity could be expected at lidocaine blood concentrations above 5 mcg/mL. The blood concentration of lidocaine is determined by the rate of systemic absorption and elimination. Longer duration of application of more than the recommended number of doses, smaller patients, or impaired elimination may all contribute to increased blood concentration of lidocaine. General Hepatic Disease Patients with severe hepatic disease are at greater risk of developing toxic blood concentrations of Lidocaine and menthol, because of their inability to metabolize lidocaine and menthol normally. Allergic Reactions Patients allergic to para-aminobenzoic acid derivatives (procaine, tetracaine, benzocaine, etc.) have not shown cross sensitivity to lidocaine. However, Lidothol Gel should be used with caution in patients with a history of drug sensitivities, especially if the etiologic agent is uncertain. Although rare, get emergency medical help if you have signs of an allergic reaction from oral or topical application of menthol: hives, difficulty breathing, or swelling of your face, lips, tongue, or throat. Non-intact Skin Application to broken or inflamed skin, although not tested, may result in higher blood concentrations of lidocaine and menthol from increased absorption. Lidothol Gel is only recommended for use on intact skin. External Heat Sources Placement of external heat sources, such as heating pads or electric blankets, over Lidothol Gel is not recommended as this has not been evaluated and may increase plasma lidocaine levels. Eye Exposure The contact of Lidothol Gel with eyes, although not studied, should be avoided based on the findings of severe eye irritation with the use of similar products in animals. If eye contact occurs, immediately wash out the eye with water or saline and protect the eye until sensation returns. Information for Patients Methemoglobinemia Inform patients that use of local anesthetics may cause methemoglobinemia, a serious condition that must be treated promptly. Advise patients or caregivers to stop use and seek immediate medical attention if they or someone in their care experience the following signs or symptoms: pale, gray, or blue colored skin (cyanosis); headache; rapid heart rate; shortness of breath; lightheadedness; or fatigue. Drug Interactions Antiarrhythmic Drugs Lidothol Gel should be used with caution in patients receiving Class I antiarrhythmic drugs (such as tocainide and mexiletine) since the toxic effects are additive and potentially synergistic. Local Anesthetics When Lidothol Gel is used concomitantly with other products containing local anesthetic agents, the amount absorbed from all formulations must be considered. Drugs That May Cause Methemoglobinemia When Used with Lidothol Gel Patients who are administered local anesthetics are at increased risk of developing methemoglobinemia when concurrently exposed to the following drugs, which could include other local anesthetics: Examples of Drugs Associated with Methemoglobinemia: Class Examples Nitrates/Nitrites nitric oxide, nitroglycerin, nitroprusside, nitrous oxide Local anesthetics articaine, benzocaine, bupivacaine, lidocaine, mepivacaine, prilocaine, procaine, ropivacaine, tetracaine Antineoplastic agents cyclophosphamide, flutamide, hydroxyurea, ifosfamide, rasburicase, Antibiotics dapsone, nitrofurantoin, para-aminosalicylic acid, sulfonamides, Antimalarials chloroquine, primaquine Anticonvulsants Phenobarbital, phenytoin, sodium valproate, Other drugs acetaminophen, metoclopramide, quinine, sulfasalazine Carcinogenesis, Mutagenesis Impairment of Fertility The effect of Lidothol Gel on fertility has not been studied. Pregnancy Teratogenic Effects Pregnancy Category B. Lidothol Gel has not been studied in pregnancy. Labor and Delivery Lidothol Gel has not been studied in labor and delivery. Nursing Mothers Lidothol Gel has not been studied in nursing mothers. Pediatric Use Safety and effectiveness in pediatric patients have not been established.