SPECIAL ALERTS
Topical Anesthetic Use for Cosmetic or Medical Procedures: Public Health Advisory – January 2009; Updated March 2009
Health Canada has issued a “Dear Healthcare Professional” letter and a notice to the Canadian public regarding important safety information associated with the use of topical anesthetic agents. Recently in the U.S., the The Food and Drug Administration (FDA) issued a Public Health Advisory to remind consumers, caregivers, and healthcare professionals of potential life-threatening side effects associated with the use of topical anesthetics available as prescription and over-the-counter (OTC) products for a variety of uses, including numbing skin prior to cosmetic or medical procedures (topical lidocaine has been recently evaluated to relieve mammography discomfort).
Topical application can result in high systemic levels and lead to toxic effects (eg, methemoglobinemia, irregular heart beats, seizures, coma, respiratory depression, death). Children may be at an increased risk for adverse effects, as well as individuals who, without the supervision of trained professionals, apply large amounts of anesthetics (or cover large areas of the skin), leave these products on for long periods of time, or use materials, wraps, or dressings to cover the skin after anesthetic application.
Both the FDA and Health Canada are recommending that when topical anesthetics are needed prior to procedures, consumers ask their healthcare provider for instructions on safe use of these products, use only approved products, and use products with the lowest amount of anesthetic while applying the least amount possible to relieve pain. If a high degree of pain is expected that is not controlled by appropriate amounts of topical anesthetics, consumers should ask their physician for alternative techniques for pain control.
Additional information can be found at:
U.S.: http://www.fda.gov/Drugs/DrugSafety/PublicHealthAdvisories/ucm110625.htm
Canada: Canada: http://www.hc-sc.gc.ca/dhp-mps/medeff/advisories-avis/prof/_2009/emla_ametop_hpc-cps-eng.php
U.S. BRAND NAMES — Cetacaine®; Exactacain™
PHARMACOLOGIC CATEGORY
Local Anesthetic
DOSING: ADULTS — Anesthesia: Topical:
Cetacaine®:
Aerosol: Apply for ≤ 1 second; use of sprays >2 seconds is contraindicated
Gel: Apply ~1/2 inch (13 mm) x 3/16 inch (5 mm); application of >1 inch (26 cm) x 3/16 inch (5 mm) is contraindicated
Liquid: Apply 6-7 drops (0.2 mL); application of >12-14 drops (0.4 mL) is contraindicated
Exactacain™ : 3 metered sprays (use of >6 metered sprays is contraindicated)
DOSING: PEDIATRIC — Dose has not been established; dose reduction is suggested
DOSING: ELDERLY — Dose reduction is suggested; refer to adult dosing.
DOSAGE FORMS — Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Aerosol, topical [spray]:
Cetacaine®: Benzocaine 14%, butamben 2%, and tetracaine hydrochloride 2% (56 g) [delivers benzocaine 28 mg, butamben 4 mg, and tetracaine hydrochloride 4 mg per second; contains benzalkonium chloride and CFCs; packaged with cannula]
Exactacain™ : Benzocaine 14%, butamben 2%, and tetracaine hydrochloride 2% (60 g) [delivers benzocaine 9.3 mg, butamben 1.3 mg, and tetracaine 1.3 mg per metered spray; contains benzalkonium chloride; cherry flavor; packaged with 100 disposable applicators]
Gel, topical:
Cetacaine®: Benzocaine 14%, butamben 2%, and tetracaine hydrochloride 2% (29 g) [provides benzocaine 28 mg, butamben 4 mg and tetracaine hydrochloride 4 mg per 0.5 inch (13 mm) x 3/16 inch (5 mm) application; contains benzalkonium chloride]
Liquid, topical:
Cetacaine®: Benzocaine 14%, butamben 2%, and tetracaine hydrochloride 2% (56 g) [provides benzocaine 28 mg, butamben 4 mg, and tetracaine hydrochloride 4 mg per 6-7 drops (0.2 mL); contains benzalkonium chloride]
DOSAGE FORMS: CONCISE
Aerosol, topical [spray]:
Cetacaine®: Benzocaine 14%, butamben 2%, and tetracaine 2% (56 g)
Exactacain™ : Benzocaine 14%, butamben 2%, and tetracaine 2% (60 g)
Gel, topical:
Cetacaine®: Benzocaine 14%, butamben 2%, and tetracaine 2% (29 g)
Liquid, topical:
Cetacaine®: Benzocaine 14%, butamben 2%, and tetracaine 2% (56 g)
GENERIC EQUIVALENT AVAILABLE — No
ADMINISTRATION — Avoid application to large areas of broken skin, especially in children. When possible, apply to clean, dry area, however, tissue need not be dried prior to application. When administering a spray formulation, the number of sprays administered and the length of each spray should be monitored and recorded.
Aerosol (Exactacain™ ): Insert disposable applicator into the spray nozzle on can. Apply directly to the site where pain or gag control is desired for procedure (ear, nose, mouth, pharynx, larynx, trachea, bronchi, esophagus, vagina, or rectum). Discard applicator after each use.
Gel (Cetacaine®): Spread thinly and evenly over application area.
Liquid (Cetacaine®): Apply with cotton applicator or directly onto tissue; do not hold applicator in position for prolonged periods of time.
USE — Topical anesthetic to control pain in surgical or endoscopic procedures; anesthetic for accessible mucous membranes except for the eyes
ADVERSE REACTIONS SIGNIFICANT — Frequency not defined. Also see individual monographs for Benzocaine and Tetracaine.
Dermatologic: Contact dermatitis (eg, erythema, pruritus, vesiculation, oozing); dehydration of the epithelium; escharotic effect
Miscellaneous: Hypersensitivity/anaphylaxis reaction (rare)
CONTRAINDICATIONS — Hypersensitivity to benzocaine, butamben, tetracaine, or any component of the formulation; ophthalmic use; cholinesterase deficiencies; large areas of denuded or inflamed tissue; administration in excess of product labeling
WARNINGS / PRECAUTIONS
Concerns related to adverse effects: Methemoglobinemia: Has been reported following topical benzocaine use (rare), particularly with higher concentration (14% to 20%) spray formulations applied to the mouth or mucous membranes. The classical clinical finding of methemoglobinemia is chocolate brown-colored arterial blood. However, suspected cases should be confirmed by co-oximetry, which yields a direct and accurate measure of methemoglobin levels. Standard pulse oximetry readings or arterial blood gas values are not reliable. Clinically-significant methemoglobinemia requires immediate treatment. Use caution with breathing problems (asthma, bronchitis, emphysema, in smokers), inflamed/damaged mucosa, heart disease, children <6 months of age, and hemoglobin or enzyme abnormalities (glucose-6-phosphate dehydrogenase deficiency, hemoglobin-M disease, NADH-methemoglobin reductase deficiency, pyruvate-kinase deficiency). Alternatives to benzocaine sprays, such as topical lidocaine preparations, should be considered for patients at higher risk of this reaction.
Special populations: Acutely ill patients: Use with caution in acutely ill patients; dose adjustment is suggested. Debilitated patients: Use with caution in debilitated patients; dose adjustment is suggested. Elderly: Use with caution in the elderly; dose adjustment is suggested. Pediatrics: Use with caution in very young patients; dose adjustment is suggested.
Other warnings/precautions: Administration: For topical use only. Do not use under dentures or cotton rolls; retention of active ingredients may cause escharotic effect.
DRUG INTERACTIONS — There are no known significant interactions.
PREGNANCY IMPLICATIONS — Safety has not been established; use is not recommended during early pregnancy unless the potential benefits outweigh the risks.
MONITORING PARAMETERS
Monitor patients for signs and symptoms of methemoglobinemia such as pallor, cyanosis, nausea, muscle weakness, dizziness, confusion, agitation, dyspnea and tachycardia. The classical clinical finding of methemoglobinemia is chocolate brown-colored arterial blood. However, suspected cases should be confirmed by co-oximetry, which yields a direct and accurate measure of methemoglobin levels. Standard pulse oximetry readings or arterial blood gas values are not reliable. Clinically significant methemoglobinemia requires immediate treatment.
MECHANISM OF ACTION — Reversible blockage of initiation and conduction of nerve impulses by deceasing the neuronal membrane’s permeability to sodium ions
PHARMACODYNAMICS / KINETICS — Also see individual monographs for Benzocaine and Tetracaine.
Onset of action: ~30 seconds
Duration: 30-60 minutes
Metabolism: Plasma via hydrolysis by cholinesterase to inactive metabolites
Excretion: Urine (as inactive metabolites)