Local Anesthetics
Local anesthetics can be used in various formulations for the treatment of pain. They are commonly used to anesthetize the skin prior to interventional therapy and are often used in the injections themselves. In addition, lidocaine can be applied topicall
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Local Anesthetics Robert M. Chow and Mohammed Issa
Local Anesthetics Local anesthetics can be used in various formulations for the treatment of pain. They are commonly used to anesthetize the skin prior to interventional therapy and are often used in the injections themselves. In addition, lidocaine can be applied topically as well as intra venously.
Mechanism of Action Local anesthetics work at the voltage-gated sodium channels, blocking their activity. This prevents the formation of an action potential and subsequent propagation of electrical signaling.
R.M. Chow, MD (*) Department of Anesthesiology, University of Maryland Medical Center, 22 South Greene ST, S11C13, Baltimore, MD 21201, USA e-mail: [email protected] M. Issa, MD Department of Anesthesiology and Psychiatry, Brigham and Women’s Hospital, 75 Francis Street, Boston, MA 02115, USA e-mail: [email protected]
Examples Generic Lidocaine Lidocaine Bupivacaine Mepivacaine
Brand name Lidoderm Topicaine Marcaine Carbocaine
Starting dose 1 patch q day Thin layer TID Not for home use Not for home use
Side effects Common Erythema Dermatitis Urticaria Paresthesia
Rare CNS depression Bradycardia Methemoglobinemia Anaphylactoid Seizure Arrhythmia
Drug Interactions Lidocaine is a major substrate for CYP1A2 and CYP3A4. Medications that affect these enzymes can drastically alter the blood levels of lidocaine and thus should be used with caution. This includes β-blockers, St. John’s wort, and amiodarone.
Clinical Clinical Indications Neuropathic pain, musculoskeletal pain
© Springer International Publishing Switzerland 2017 R.J. Yong et al. (eds.), Pain Medicine, DOI 10.1007/978-3-319-43133-8_49
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Initiation: Up to three lidocaine patches can be applied to a patient’s skin for up to 12 h in a 24 h period. Lidocaine gel can be applied up to three times daily in a thin layer over the affected area. The dose should not exceed 4.5 mg/kg or 300 mg. Though there is no standard for the dosing of intravenous lidocaine in the treatment of chronic pain, it has been shown to be a useful adjunct in the treatment of chronic pain. One possible dose is 500 mg in 250 mL of normal saline infused over 30 min. However, of note no difference in efficacy was noted when comparing lidocaine doses of 5–7.5 mg/kg.
be prolonged with hepatic impairment.
Clinical Pearls • When using lidocaine patches, the 12 h on and 12 h off concept is used to prevent tachyphylaxis. • While amide local anesthetic allergies are extremely rare, often patients will report allergic reactions to the adhesive or binding agents. • Intralipid can be used to treat local anesthetic toxicity. A bolus of 1.5 to 4mL/kg can be used followed by an infusion of 0.25 to 0.5mL/kg/min.
Weaning No weaning is needed.
Special Considerations • Safe in renal failure patients. • Elimination half-life is 90–120 min but may
Suggested Readings Ferrera de Souza M, et al. The analgesic effect of intravenous lidocaine infusion in the treatment of chronic pain: a literature review. Rev B
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