BLT Numbing Cream is a combination of lidocaine, an amide local anesthetic, and benzocaine, tetracaine, an ester local anesthetic.
Practitioners are increasingly using BLT Cream as a topical anesthetic (Benzocaine/Lidocaine/Tetracaine) in the field of dermatology, endoscopy, surgery, and dental procedures. It can be used for gag reflex suppression as well. BLT Cream compound formula is one of the strongest numbing creams that dermatologists use also known as triple topical anesthetic. Application of BLT numbing Cream prior to performing dermatologic procedures such as cosmetic skin treatments has proven to decrease pain and discomfort associated with these procedures. Despite the prevalent use of topical anesthetics, there are few standard guidelines for about which products provide optimal and safest use. Adverse events are often correlated with the improper application of topical anesthetics. Careful attention must be paid to this compounded product in order to prevent adverse events.
BLT CREAM COMPOUND FORMULA INDICATIONS AND USAGE
BLT Cream is a combination of lidocaine, an amide local anesthetic, and benzocaine, tetracaine, an ester local anesthetic. It is indicated for use on intact skin in adults to provide topical local analgesia for superficial dermatological procedures such as:
- Dermal filler injection
- Pulsed dye laser therapy
- Facial laser resurfacing
- Laser-assisted tattoo removal
- Before Tattoo
TOPICAL ANESTHETICS MECHANISM OF ACTION
Lidocaine is an amide-type local anesthetic agent and benzocaine, tetracaine is an ester-type local anesthetic agent. Benzocaine, lidocaine, and tetracaine block sodium ion channels required for the initiation and conduction of neuronal impulses which, in certain instances, result in local anesthesia. When applied to intact skin, BLT Cream provides local dermal analgesia by the release of benzocaine, lidocaine, and tetracaine from the peel into the skin. Both Lidocaine and benzocaine cause a similar anesthetic sensation. They both reduce pain and sensation to a specific area of the body as local anesthetics that. Both Lidocaine and benzocaine are equally effective in reducing pain relief. They have similar side effects, most commonly stinging or local skin issues.
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TOPICAL ANESTHETICS PHARMACOKINETICS
The amount of benzocaine, lidocaine, and tetracaine systemically absorbed from BLT Cream is directly related to both the duration of application and the surface area over which it is applied.
It is not known if benzocaine, lidocaine, and tetracaine are metabolized in the skin. Benzocaine metabolism occurs in the liver and metabolites are excreted renally. Lidocaine is metabolized rapidly by the liver to a number of metabolites, including monoethylglycinexylidide (MEGX) and glycinexylidide (GX). Both lidocaine and benzocaine have pharmacologic activity similar to, but less potent than that of lidocaine. The major metabolic pathway of lidocaine, sequential N-deethylation to MEGX and GX, is primarily mediated by CYP1A2 with a minor role of CYP3A4. The metabolite, 2,6- xylidine, has unknown pharmacologic activity. Following intravenous administration of lidocaine, MEGX and GX concentrations in serum range from 11% to 36% and from 5% to 11% of lidocaine concentrations, respectively. Serum concentrations of MEGX were about one-third of the serum lidocaine concentrations. Tetracaine undergoes rapid hydrolysis by plasma esterases. Primary metabolites of tetracaine include para-aminobenzoic acid and diethylaminoethanol, both of which have an unspecified activity.
The half-life of benzocaine and lidocaine elimination from the plasma following intravenous administration is approximately 1.8 hr. Lidocaine and its metabolites are excreted by the kidneys. More than 98% of an absorbed dose of lidocaine can be recovered in the urine as metabolites or parent drug. Less than 10% of lidocaine is excreted unchanged in adults, and approximately 20% is excreted unchanged in neonates. The systemic clearance is approximately 8–10 mL/min/kg. During intravenous studies, the elimination half-life of lidocaine was statistically significantly longer in elderly patients (2.5 hours) than in younger patients (1.5 hours). The half-life and clearance for tetracaine have not been established for humans, but hydrolysis in the plasma is rapid.
Elderly: The levels are similar to or lower than those for younger patients receiving similar amounts of BLT Cream.
Cardiac, Renal and Hepatic Impairment: No specific pharmacokinetic studies were conducted. The half-life of lidocaine may be increased in patients with cardiac or hepatic dysfunction. There is no established half-life for tetracaine due to rapid hydrolysis in the plasma.
Popular Compounded Topical Anesthetic Gels for Dentistry in Orthodontics
Regardless of brand name, mucosal compound topical anesthetics are relatively similar. Each contains a combination of high-dose anesthetics, including both ester-type (tetracaine) and
amide-type (lidocaine and prilocaine). This provides profound numbness, as well as other inactive ingredients for structure and taste. Some formulations also contain vasoconstrictors such as phenylephrine—though it is debatable what this agent truly contributes. Orthodontists should be familiar with a few of the most popular mucosal compounded topical anesthetics:
TAC 20% Alternate
Also known as TAC Alternate, contains two anesthetic agents (20% lidocaine and 4% tetracaine) and one vasoactive agent (2% phenylephrine). The original TAC, composed of tetracaine, epinephrine (adrenaline), and cocaine, was once commonly used in hospital emergency departments as a dermal topical anesthetic to provide pain relief and vasoconstriction prior to suturing.
TAC Alternate is somewhat of a misnomer since the formulation does not contain cocaine. Its active ingredients are identical to those of LET (lidocaine, epinephrine, and tetracaine).
Is a topical anesthetic gel compounded from three anesthetic agents (10% lidocaine, 10% prilocaine, and 4% tetracaine)? Its equal concentration of lidocaine and prilocaine is similar to that
of two FDA-approved topical anesthetics: EMLA cream (2.5% lidocaine and 2.5% prilocaine), which provides dermal anesthesia prior to venipuncture, and Oraqix (2.5% lidocaine and 2.5%
prilocaine), which is inserted into the gingival sulcus before root planing. Dr. Graham has introduced Profound PET (for “phenylephrine thick”),11 or Profpet, which adds a vasoactive agent (2%
phenylephrine) and methylcellulose for greater viscosity.
DēpBlu anesthetic gel
Was developed by Dr. Jason Cope and has the same active ingredients as those of Profound PET.
Baddest Topical in Town (BTT)
Composed of three anesthetics (12.5% prilocaine, 12.5% tetracaine, and 3% lidocaine) and a vasoactive agent (3% phenylephrine). Dr. Nicozisis introduced BTT for use with Propel transmucosal alveolar micro-osteoperforation.5 The high concentration of tetracaine provides strong, penetrating anesthesia. Another popular topical compound, the Best Topical Ever, uses similar active ingredients but reverses the concentration of lidocaine and prilocaine (12.5% lidocaine, 12.5% tetracaine, and 3% prilocaine).
BLT CREAM PATIENT COUNSELING INFORMATION
Prior to treatment, advise the patient of the following blt numbing cream side effects:
- BLT Cream is intended for use in a clinical setting under the supervision of a healthcare provider and is not for home use by patients.
- Topical anesthetic (Benzocaine/Lidocaine/Tetracaine) is contraindicated in patients with a known history of sensitivity to benzocaine, lidocaine, and tetracaine, local anesthetics of the amide or ester type, or any other component of the product and in patients with para-aminobenzoic acid (PABA) hypersensitivity.
- BLT Cream should be used with caution in patients who may be more sensitive to the systemic effects of benzocaine, lidocaine, and tetracaine, including the acutely ill, the debilitated, and those with compromised hepatic function. Patients with severe hepatic disease or pseudocholinesterase deficiency are at greater risk of developing toxic plasma concentrations.
- Topical anesthetic Cream should be used with caution in patients receiving class I antiarrhythmics and/or other local anesthetics, because the systemic toxic effects may be additive and potentially synergistic with benzocaine, lidocaine, and tetracaine.
- BLT Cream should not be used if the patient has a history of methemoglobinemia.
- Contact of BLT Cream with the eyes should be avoided. If eye contact occurs, immediately wash out the eye with water or saline and protect the eye until sensation returns.
- BLT Cream is not for use on mucous membranes or on broken skin.
- If skin irritation or a burning sensation occurs during application, the product should be removed.
- If signs of an allergic or anaphylactoid reaction (urticaria, angioedema, bronchospasm, and shock) occur, instruct patients to seek immediate emergency help.
- Topical application of local anesthetics such as BLT Cream may lead to diminished or blocked sensation in the treated skin; therefore, patients should avoid inadvertent trauma (rubbing, scratching, or exposure to heat or cold) before complete sensation returns.
- The effect of BLT Cream on intradermal injections of live vaccines has not been determined.
- Methemoglobinemia warning: Use of benzocaine may cause methemoglobinemia, a serious condition that must be treated promptly because it reduces the amount of oxygen carried in the blood. This can occur even if you have used this product before. Stop use and seek immediate medical attention.
What are good prescription numbing creams for dermatologic Procedures?
Practitioners are increasingly using prescription numbing creams to decrease the pain associated with superficial dermatologic, aesthetic, and laser procedures. Numerous lidocaine-containing products are available, the most popular is lidocaine cream available over the counter. Lidocaine cream is used as tattoo numbing cream.
MATERIALS AND METHODS A literature review of currently available for prescription numbing creams, their safety profiles, and dermatologic uses was conducted.
RESULTS Factors that should be considered to reduce the risk of side effects associated with the use of prescription numbing creams include the amount of product used, body location, size of the surface area, and duration of product application. Many case reports document adverse outcomes associated with the use of compounded numbing creams that the Food and Drug Administration has not approved that have inappropriately high anesthetic concentrations and from the use of numbing creams on excessively large skin surface areas during laser treatments.
CONCLUSIONS Lidocaine-containing products play an integral role in cutaneous anesthesia by providing patient comfort with minimal side effects. Careful attention must be paid to the particular anatomic location, the total surface area covered, and the duration of anesthetic skin contact.
JOSEPH F. SOBANKO, MD,* CHRISTOPHER J. MILLER, MD,* AND TINA S. ALSTER, MD†
The authors have indicated no significant interest with commercial supporters.
Topical prescription numbing creams decrease pain during cutaneous procedures in the outpatient setting and permit a variety of dermatologic procedures to be performed without anatomic distortion from a local anesthetic injection. As the number of in-office dermatologic procedures continues to grow, practitioners will benefit from awareness of the indications, pharmacologic mechanisms, appropriate methods of application, and safety profiles of the currently available prescription and over-the-counter (OTC) numbing creams.
Historical Background of Prescription Numbing Creams
“Coca” was a term used by the Incas for the substance derived from the plant Erythroxylum coca. The Incas initially reserved the use of coca for their monarch during religious ceremonies. After discovering its anesthetic and stimulatory properties, Peruvians subsequently began to cultivate the plant for commercial distribution. Over time, the plant became a staple of Peruvian culture. Peruvians carried the plant in sidebags called “chuspas” to have it available for chewing. In 1860, Niemann isolated the plant’s active ingredient, cocaine,2 but it was not until 1884 that ophthalmic surgeon Karl Koller demonstrated that general anesthesia could be avoided for ophthalmic procedures by application of cocaine to the conjunctiva.3 Additional ester anesthetics, such as procaine and tetracaine, were created in the early 20th century, but these were noted to result in high rates of allergic contact dermatitis. In 1943, Loefgren synthesized the first amide anesthetic, lidocaine. Subsequently, a large number of topical formulations of esters, amides, and adrenaline have been developed and used for dermatologic procedures. Although the topical formulations are generally safe, allergic reactions, systemic absorption, and death can occur when care is not observed with the use of these products.
Specific FDA-Approved Topical Anesthetics
Topical anesthetics exist in many different preparations and vehicles for delivery. Eutectic mixtures allow individual anesthetic compounds, which are normally in the solid state at room temperature, to be combined as liquids. Eutectic mixtures permit higher concentrations of anesthetic to be used safely and facilitate application to the skin. Liposomal encapsulation is another vehicle that facilitates percutaneous drug delivery. Liposomes are microscopic, spherical, phospho-lipid-based carriers that deliver a greater concentration of local anesthetic to sensory nerves than other conventional formulations with a lower lipophilicity. Improper application of topical anesthetic preparations such as benzocaine cream, lidocaine cream, and tetracaine may cause serious complications, including death. Prolonged application, use of inappropriately high concentrations, and application to large surface areas before outpatient procedures increase the risk of cardiotoxicity and central nervous system toxicity. In general, the central nervous system is more susceptible to the pharmacologic actions of local anesthetics that is the cardiovascular system. The initial symptoms of anesthetic-induced toxicity include lightheadedness, circumoral numbness, diplopia, and tinnitus. (See Table 3 for additional signs and symptoms of lidocaine toxicity.) Many adverse reactions also appear to be related to the inclusion of epinephrine within the anesthetic mixture. In 2006, the FDA warned five pharmacies to discontinue compounding standardized versions of topical anesthetic creams that were already available for general distribution. Concern grew because of the presence of higher concentrations of the compounded anesthetic mixtures than in the FDA-approved products. In addition, the compounded products often lacked appropriate warnings or directions for use. Many of the compounded anesthetics that received a warning from the FDA included products with unknown strengths of active anesthetic and also contained sympathomimetic agents such as phenylephrine, which limits the compounded product’s shelf life because of light sensitivity and increases adverse events related to hypertension and vasoconstriction. Standardization of compounded numbing creams proves difficult because individual pharmacies use different protocols to mix various ingredients in their topical anesthetics.
Despite this FDA warning, a large number of pharmaceutically compounded topical anesthetics remain in use for outpatient procedures such as laser hair removal or soft tissue augmentation (Table 4). Their mechanism of action is similar to that of FDA-approved products, but higher concentrations and various active anesthetics are mixed together. Significant variability in product quality and accurate dosing of these compounded products becomes difficult because they are packaged in widely different containers. Kravitz noted that these compounded numbing creams have a low therapeutic index and are often improperly labeled. All of these factors increase the risk of adverse events, including overdose, seizures, arrhythmias, and death and should prompt practitioners to limit the use of topical anesthetics to those approved by the FDA. The remaining portions of this chapter will focus on prescription numbing creams approved by the FDA for use during outpatient dermatologic procedures.
Clinical Applications of Topical Anesthetics
Topical anesthetics are a versatile supplement to the practice of outpatient dermatologic procedures. Application of prescription numbing creams has proven to decrease pain associated with common procedures such as shave biopsies, punch biopsies, curettage, and electrosurgery. Laser and aesthetic medicine have been strong drivers of the growth of outpatient dermatologic procedures in recent history. Listed below are popular uses of topical anesthetics for aesthetic procedures.
Strongest Topical Anesthetics for Laser and Light-Based Procedures
The most common laser procedure for which numbing creams are used is laser-assisted hair removal, particularly in such sensitive areas as the upper lip and inguinal region.
Best Prescription Numbing Creams for Cosmetic Injectables
Although the application of topical anesthetics is common before injection of dermal fillers, it is generally not necessary for botulinum toxin injection.
Best Numbing Creams for Ablative Laser Skin Resurfacing Treatments
Before the advent of such effective topical anesthetics (alone or in combination), ablative skin resurfacing procedures using carbon dioxide (CO2) and erbium-doped YAG lasers often required the use of intravenous sedation. With the recent introduction of more-superficial ablative procedures and devices (including single-pass CO2 and fractional laser and plasma skin resurfacing), the ability to obtain adequate intraoperative anesthesia with topical application of anesthetics has been achieved.
Best Topical Anesthetic for Chemical Peel
Application of topical anesthetics before chemical peeling has been shown to reduce discomfort without decreasing clinical efficacy of the peel. In a study assessing the use of topical anesthesia for peels, lidocaine was applied without occlusion for 30 minutes after a superficial unbuffered 70% glycolic acid peel and before a medium-depth 35% trichloroacetic acid (TCA) peel.
Tattoo Numbing Cream
Lidocaine-containing products and lidocaine cream play an integral role by providing patient comfort with minimal side effects. Application of topical anesthetic preparations such as benzocaine cream, lidocaine cream, and tetracaine can be used.
Tips for Best Topical Anesthetic Use and Increasing Patient Comfort
No standard guidelines exist for optimal use and safety of all topical anesthetics. Practitioners should read the package inserts of individual products and be completely familiar with their unique characteristics. Suggestions on safe application relate to the size of the anatomic area to be applied, the age and weight of the patient, and the amount (in grams) of anesthetic to be applied. Unfortunately, guidelines do not explicitly stratify the recommended dosage based on the anatomic area to be treated. Absorption of prescription numbing cream will occur more effectively over thin genital mucosal skin than on much thicker acral skin. Product inserts typically recommend the avoidance of application to oral mucosa and to the eyes to prevent severe ocular irritation.
Practitioners are increasingly using topical anesthetics to decrease the pain associated with superficial dermatologic, aesthetic, and laser procedures. Lidocaine-containing products and lidocaine cream play an integral role by providing patient comfort with minimal side effects. Careful attention must be paid to the particular anatomic location, the total surface area covered, and the duration of anesthetic skin contact. Many case reports document adverse outcomes associated with the use of compounded non-FDA-approved products that have inappropriately high anesthetic concentrations and from the use of topical anesthetics on excessively large skin surface areas during laser treatments. Careful selection and application of best topical anesthetic can decrease or eliminate pain during many cutaneous procedures, reduce anatomic distortion by minimizing the volume of intradermal local anesthesia and decrease anxiety in patients who fear pain from procedures.
RESEARCH STUDIES OF TOPICAL ANESTHETICS
- Cetacaine Topical Anesthetic (benzocaine; lidocaine; tetracaine) package insert. Pennsauken, NJ: Cetylite Industries, Inc.; 2013 Apr.
- Exactacain Topical Anesthetic Spray (benzocaine; lidocaine; tetracaine) package insert. Cumberland, RI: Onset Therapeutics; 2008 Sep.
- One Touch Advanced Topical Anesthetic Gel (benzocaine; lidocaine; tetracaine) package insert. Odessa, FL: Hager Worldwide; 2009 Jun.
- Cousins MJ, Bridenbaugh PO. Neural blockade in clinical anesthesia and management of pain. 4th edn. Philadelphia: Lippincott Williams & Wilkins; 2008.
- Drug Facts and Comparisons 2011. 65th edn. St Louis: Lippincott Williams & Wilkins; 2010. Facts & Comparisons.
- Moore TJ, Walsh CS, Cohen MR. Reported adverse event cases of methemoglobinemia associated with benzocaine products. Arch Intern Med 2004;164:1192-5.
- FDA Drug Safety Communication: FDA continues to receive reports of a rare, but serious and potentially fatal adverse effect with the use of benzocaine sprays for medical procedures. Retrieved April 7, 2011.
- FDA Drug Safety Communication: Reports of a rare, but serious and potentially fatal adverse effect with the use of over-the-counter (OTC) benzocaine gels and liquids applied to the gums or mouth. Retrieved April 7, 2011.
- Michalowicz BS, DiAngelis AJ, Novak MJ, et al. Examining the safety of dental treatment in pregnant women. J Am Dent Assoc. 2008;139:685-695.
- National Institutes of Health (NIH). Tetracaine monograph. LactMed: Drug and Lactation Database. Available at http://toxnet.nlm.nih.gov/cgi-bin/sis/search/f?./temp/~hiRQ6t:1. Accessed March 28th, 2012.
- American Academy of Pediatrics (AAP) Committee on Drugs. Transfer of drugs and other chemicals into human milk. Pediatrics 2001;108:776-89.
- Burkhart CG, Burkhart CN. Decreased efficacy of topical anesthetic creams in presence of benzoyl peroxide. Dermatol Surg 2005;31:1479-80.
- Citanest Plain Dental (prilocaine hydrochloride) package insert. York, PA: Dentsply Pharmaceutical; 2010 Jun.
- Benzocaine/Lidocaine/Tetracaine Cream Report of Corneal Damage and Review J Clin Aesthet Dermatol. 2016 Mar; 9(3): 48–50.
- Topical anesthesia J Anaesthesiol Clin Pharmacol. 2015 Oct-Dec;
- Comparative Study of Compounded Anesthetic Benzocaine/Lidocaine/Tetracaine (BLT) Cream with and without Abrasive Particles. J Clin Aesthet Dermatol. 2017 Apr;10(4):30-36.
- Benzocaine/Lidocaine/Tetracaine Cream: Report of Corneal Damage and Review.
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