Rx Update: December 2004
Joan Murhammer, R.Ph., Mary Ross, R.Ph., M.B.A., Kevin Bebout,
R.Ph.
Peer Review Status: Internally Reviewed
Lidocaine is an anti-arrhythmic agent and a local anesthetic that is used for infiltration, nerve block, epidural and subarachnoid anesthesia, and topical anesthesia. To minimize systemic exposure and toxicity, the smallest dose and the lowest concentration of lidocaine required to produce the desired effect should be used. Maximum recommended doses should not be exceeded and the total dose of lidocaine should be calculated from all sources of lidocaine exposure (e.g., injection, topical). Signs and symptoms of lidocaine toxicity are dose related and include dizziness, nausea, drowsiness, speech disturbances, periorbital numbness, muscle twitching, confusion, vertigo, and tinnitus. More serious signs of toxicity are difficulty breathing, seizures, psychosis, and bradycardia.
The dose of lidocaine needed for anesthesia depends on the type of procedure, degree of anesthesia required, and the patient’s response. The dose should generally be reduced in children, elderly, or debilitated patients. In normal healthy adults, the maximum recommended dose of lidocaine injection with epinephrine for local anesthesia other than spinal should not exceed 7 mg/Kg, and the maximum total dose should not exceed 500 mg. Lidocaine injection with epinephrine should not be used on fingers and toes. The maximum recommended dose of lidocaine injection without epinephrine should not exceed 4.5 mg/Kg, and the maximum total dose should not exceed 300 mg. Once given the maximum dose of lidocaine, it should not be repeated for 2 hours.
Viscous lidocaine 2% is typically dosed as 15 ml (300 mg) orally swish and spit/swallow every 3 hours as needed in adults. Patients should not exceed 8 doses in 24 hours. Adverse effects such as dizziness, light-headedness, and numbness of the tongue have been reported with 500 mg oral doses of lidocaine. Topical administration of lidocaine in adults and children should not exceed 3 mg/Kg/dose (e.g., 4.2 gm of a 5% ointment for a 70 Kg patient). The dose should not be repeated within 2 hours.
The maximum adult dose for the lidocaine 5% patch (Lidoderm) is up to 3 patches may be applied at a time for no more than 12 hours per 24-hour period. Lidocaine 4% cream (L.M.X.4) should not be applied to an area over 100 cm2 for patients under 10 Kg and an area over 600 cm2 for patients between 10 and 20 Kg. The amount absorbed systemically is determined by the area over which it is applied and the duration of application, particularly if it is left on for longer than 2 hours to a large surface area.
The recommended maximum dose, application area, and application time of lidocaine 2.5% with prilocaine 2.5% cream (EMLA), depend upon the weight and age of the patient. Children under 3 months of age or less than 5 Kg can receive up to 1 gm over 10 cm2 for up to 1 hour. Children 3 to 12 months of age and over 5 Kg can receive up to 2 gm per dose over 20 cm2 for up to 4 hours. Children 1 to 6 years of age and more than 10 Kg can receive up to 10 gm per dose over 100 cm2 for up to 4 hours, and children 7 to 12 years old and greater than 20 Kg can receive up to 20 gm per dose over a 200 cm2 area for up to 4 hours.
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