Pharmacology Department
Customizing Compounded Topical Anesthetic Preparations Sahar Whelan, RPh, BScPhm, MScPhm Souha Mourad, RPh, BScPhm
T
he administration of topical anesthetics to control pain associated with cosmetic procedures avoids the risks associated with infiltrative local anesthesia injections and the associated pain from the injections. The ideal topical anesthetics would provide complete anesthesia following a simple pain-free application, not contain narcotics or controlled substances, and be safe to use (http:// www.custommedicine.com.au/health-articles/topicalanesthetics). The most popular local anesthetics used include lidocaine, benzocaine, tetracaine, and prilocaine (Topical Anesthetics, 2013, http://www.custommedicine .com.au/health-articles/topical-anesthetics). Many dosage forms such as gels, sprays, creams, ointments, and patches provide the clinical response with precise options for application under various circumstances (Windle & Kulkarni, 2013). The demand for professional compounding of customized preparations has increased as patients and health care professionals realize that the limited number of strengths and dosage forms that are commercially available do not meet the needs of each individual. The following is a discussion on the customization of topical anesthetic preparations, which may lead patients to having a better response and receiving “just what the doctor ordered” (http://www.custommedicine.com.au/health-articles/ topical-anesthetics). To customize the local anesthetic, one must not only understand the pharmacology of local anesthetics but Sahar Whelan, RPh, BScPhm, MScPhm, graduated from the University of Toronto, Ontario, Canada, in 1988 with a bachelor’s degree in pharmacy and in 1990 with a master’s degree. She worked in the Retail and hospital sector; being the Director of Infusion Pharmacies, she specialized in compounding intravenous, nutrition, oral, dermatological, and sterile ophthalmic products. Souha Mourad, RPh, BScPhm, is a registered Pharmacist in the Province of Ontario, Canada and has more than four decades of pharmacy experience in the Middle East and Canada in areas such as hospital and retail. She specializes in the sterile and nonsterile compounding of various products for patients who require specific products not commercially available. She focuses on the customized needs of the patient. The authors report no conflicts of interest. This article was written with strict ethical adherence and no funding was obtained to write the article. Address correspondence to Sahar Whelan, RPh, BScPhm, MScPhm, Concord Specialty Pharmacy, 2180 Steeles Avenue W, Unit 4, Concord, Ontario, Canada L4K 2Z5 (e-mail: [email protected]). DOI: 10.1097/PSN.0000000000000024
Plastic Surgical Nursing
understand the patient as well. This enables the anesthetist to predict the potency, speed of onset, duration of action, and safety of a specific drug in a given clinical situation. This maximizes the opportunity for safe and effective use of local anesthesia.
PHARMACOLOGY OF LOCAL ANESTHETICS The definition of a local anesthetic is “a drug which reversibly prevents transmission of the nerve impulse in the region to which it is applied, without affecting consciousness” (Edgcombe & Hocking, 2005). The structural classification of local anesthetics relates to their lipid-soluble hydrophobic aromatic group or the charged, hydrophilic amide group. This bond determines the class and may be amide or ester. The amides include lidocaine, bupivacaine, and prilocaine. The esters include cocaine, benzocaine, and amethocaine. Esters’ metabolism results in the production of para-aminobenzoate (PABA) that is associated with allergic reactions. But the amides very rarely cause allergic phenomena and that’s why amides are more commonly used than esters. To quickly determine whether an anesthetic agent is an ester or an amide, note whether the generic name contains the letter i once or twice. Esters contain the letter i once in their generic names, whereas the generic names for amides contain the letter i twice (Principles of Skin Therapy, 2013, http://www.dermweb .com/therapy/overview.htm). The pKa of a local anesthetic is a quantitative measure of the strength of an acid in solution or, in the simplest of terms, represents the ability of the drug to cross the lipid cell membrane in a physiological pH of 7.4. The local anesthetics with a pKa closest to pH of 7.4 will reach its target site more quickly. For example, lidocaine (pKa of 7.9) has a faster onset of action than bupivacaine (pKa of 8.1). In addition, it is important to note that infected tissue tends to be a more acidic environment than usual and the pH is reduced significantly so the onset of action of local anesthetics is reduced and the effect is delayed. Consequently, the increased blood supply of the infected tissue will cause more of the local anesthetic to be removed from the area before it can affect the nerve (Edgcombe & Hocking, 2005). www.psnjournalonline.com
25
Copyright © 2014 American Society of Plastic Surgical Nurses. Unauthorized reproduction of this article is prohibited.
PSN-D-13-00041.indd 25
2/14/14 9:57 PM
Pharmacology Department
The Esters are broken down rapidly by plasma esterases to inactive compounds and consequently have a short half-life. Cocaine is broken down in the liver. But ester metabolites are excreted from the kidneys. The amides are metabolized in the liver by amidases. This process is slower so the half-life is longer and repeated doses can cause accumulation. Prilocaine is metabolized outside of the liver as well (Edgcombe & Hocking, 2005). Adrenaline’s vasoconstrictor properties can minimize the vasodilator effect of lidocaine and decrease the rate at which drug is removed from the site of action by absorption in the systemic circulation. In addition, it reduces blood loss from the site by the same mechanism (Edgcombe & Hocking, 2005). Adrenaline may potentially induce adverse effects. Therefore, its use must be carefully considered in patients with heart disease and those patients concomitantly taking β-blockers (Niteen, 2012). Bicarbonate is also added to a local anesthetic to increase the pH of the area when administered and in this way more drug is present in the molecular lipophilic form, which crosses cell membranes easily and hence increases the speed of onset of action (Edgcombe & Hocking, 2005).
TYPES OF FORMULATIONS COMMERCIALLY AVAILABLE Now, we have a better understanding why lidocaine is the local anesthetic most frequently used. It is effective, acts rapidly, and safe and it is uncommon for any allergic reactions. It is available in different formulations; however, the commercial products available (lidocaine 2%, 5% cream and jelly, 4% tetracaine gel) may not be effective in producing sufficient pain block for some cosmetic procedures in many patients. Painless dermal local anesthesia can be achieved with the topical anesthetic Emla. This is a combination of lidocaine and prilocaine and comes in the form of cream or patches. It is particularly useful for numbing areas that require injection, especially in children (Windle & Kulkarni, 2013).
FACTORS TO CONSIDER WHEN CHOOSING A TOPICAL PREPARATION 1. An occlusive vehicle enhances penetration of the active ingredient and improves efficacy. The vehicle may be cooling, drying, emollient, or protective action. 2. Match the type of preparation with the site (e.g., gel or lotion for hairy areas) 3. Ointments and water-in-oil (w/o) creams are less irritating, while gels are irritating. a. Creams are oil-in-water or w/o emulsions 26
www.psnjournalonline.com
b. Ointments are semisolid preparations of hydrocarbons (petrolatum, mineral oil, paraffins, and synthetic hydrocarbons) i. Occlusive effect enhances absorption and improves efficacy ii. Protective film on the skin iii. Greasy and sticky, retains sweat and not suitable in hairy areas or hot weather conditions or in skin prone to folliculitis iv. Contains no water and does not require a preservative c. Pastes are a mixture of powders and ointments i. Addition of powder improves breathability. ii. Addition of powder to change an ointment into a paste increases the consistency of the preparation so it is more difficult to rub off. This is useful when trying to protect an outer area from an irritating preparation. d. Lotion is any liquid preparation in which medications are suspended or dissolved. i. Lotions are easy to apply to large areas. ii. They are suitable for hairy areas and skin prone to acne. iii. Most are aqueous or hydroalcoholic with the small amounts of alcohol added to hasten evaporation of the solvent from the skin surface. e. Gels are transparent preparations containing cellulose ethers or carbomer in water or a water-alcohol mixture i. Gels liquefy on contact with the skin, dry and leave a thin film of active medication. ii. They tend to be drying. iii. Useful in hairy areas. iv. Cosmetically acceptable. Occlusive dressings may be applied to formulations (e.g., DuoDERM, Tegaderm, Saran wrap) to improve absorption. Iontophoresis has been used to improve the effects of topical anesthesia; however, equipment is expensive and bulky and the mild electrical sensation can cause discomfort in patients (Drug Absorption, 2013, http://www.medisca.net/cen/Tips/Drug%20Absorption. pdf). Removing the stratum corneum (outermost layer of the epidermis containing dead cells) with preoperative procedures such as tape, stripping, degreasing with acetone, or laser ablation enhances dermal absorption. Heat can also facilitate anesthetic penetration into the skin (Drug Absorption, 2013, http://www.medisca.net/cen/Tips/ Drug%20Absorption.pdf). Fear of needles and pain can cause anxiety in patients awaiting procedures in the outpatient setting. Application of topical anesthetic before or in place of injection of Volume 34 Number 1 January–March 2014
Copyright © 2014 American Society of Plastic Surgical Nurses. Unauthorized reproduction of this article is prohibited.
PSN-D-13-00041.indd 26
2/14/14 9:57 PM
Pharmacology Department
local anesthetic can help relieve anxiety (Sobanko, Miller, & Alster, 2012). High plasma concentrations of topical anesthetics can cause adverse effects. The application of topical anesthetics to abraded or torn skin can result in excessive exposure. Possible adverse effects include the following: • Burning or stinging at the administration site. • Oral viscous lidocaine may cause systemic toxicity, particularly with repeated use in infants or children. • Central nervous system (CNS) stimulation, such as seizures followed by CNS depression, respiratory depression. This may be absent or minimized when amides like tetracaine are administered. Solutions that contain epinephrine may add to the CNS stimulatory effect. • Cardiovascular: Heart depression resulting in bradycardia, arrhythmias, hypotension, cardiovascular collapse, and cardiac arrest. Local anesthetics that contain epinephrine may cause tachycardia, hypertension, and angina. • Gag-reflex suppression may occur with oral administration. Other adverse effects include transient burning sensation, skin discoloration, swelling, neuritis, tissue necrosis, and sloughing and methemoglobinemia (observed with prilocaine) (Niteen, 2012). The U.S. Food and Drug Administration has issued an advisory regarding the risk of serious adverse effects with the use of topical anesthetics for cosmetic procedures. Life-threatening adverse effects occurred following topical anesthetic application over large surface areas of the body; for some, a plastic occlusive was also applied to enhance absorption. Two women experienced seizures, coma, and death following applying topical anesthetics to their legs with an occlusive dressing before laser hair removal (Public Health Advisory, 2013, http://www.fda. gov/Drugs/DrugSafety/PostmarketDrugSafetyInformation forPatientsandProviders/DrugSafetyInformationfor HeathcareProfessionals/PublicHealthAdvisories/ucm 054718.htm). Drug concentration is expressed as a percentage (e.g., dibucaine 1%, benzocaine 0.5%). Percentage is measured in grams per 100 mL (e.g., 1% is 1 g/100 mL [1000 mg/ 100 mL] or 10 mg/mL). To calculate the mg/mL concentration quickly from the percentage, move the decimal point 1 place to the right, as follows: lidocaine 2% = 20 mg/mL and benzocaine 20% = 200 mg/mL (Windle & Kulkarni, 2013). So based on the knowledge previously discussed, various compounded mixtures have been tested and are utilized in many cosmetic procedures. These compounds help achieve the ultimate goal of “complete anesthesia following Plastic Surgical Nursing
a simple pain-free application” and they are safe to use. You may order these specifically customized for your patients from experienced local compounding pharmacies. LET anesthetic gel—lidocaine, tetracaine, and epinephrine (amide, ester, and vasoconstrictor)—treats pain associated with lacerations and where skin may be broken during regular tattooing. Onset of action is usually 20–30 min after it is applied (Windle & Kulkarni, 2013). BLT gel—benzocaine, lidocaine, and tetracaine (amide and two esters)—is effective when applied prior to laser procedures. It has a rapid onset of action (20– 30 min) compared with 1–2 hr with EMLA cream and it does not require any occlusive dressing (Windle & Kulkarni, 2013). PLT gel—prilocaine, lidocaine, and tetracaine (amide and 2 esters)—may be preferable to BLT gel because there were reported incidences of methemoglobinemia with benzocaine when applied to large areas (Windle & Kulkarni, 2013). Cosmetic laser clinics utilize PLT, LET, BLT, EMLA creams, and patches and other LT (lidocaine/tetracaine) combinations that are specifically formulated for this purpose (http://www.custommedicine.com.au/healtharticles/topical-anesthetics).
SUMMARY Anesthesia in aesthetic procedures is extremely important from both the functional role and also the psychological impact on perception of the procedure by the patient. When there is successful (safe and pain-free) anesthesia for the patient, the experience is pleasant and it is more likely that the procedure will be repeated if warranted. It is important to remember that each individual patient will walk into a cosmetic procedure clinic with different perceptions of pain and comfort. With a solid knowledge of the availability of different anesthetic options, patients’ fears may be alleviated and there will be a chance for a more positive outcome. REFERENCES
Drug absorption—comparison for altered route of administration. (2013). Retrieved November 23, 2013, from http://www .medisca.net/cen/Tips/Drug%20Absorption.pdf Edgcombe, H., & Hocking, G. (2005). Local anaesthetic pharmacology 11/07/05. John Radcliffe Hospital, Oxford, UK. World Anaesthesia Tutorial of the Week. Retrieved November 20, 2013, from http://www.AnaesthesiaUK.com/WorldAnaesthesia Niteen, D. V. (2012). Local anesthesia for cosmetic procedures, clinical use of local anesthetics. Retrieved November 23, 2013, from http://www.intechopen.com/books/clinical-use-of-localanesthetics/anesthesia-for-cosmetic-procedures Principles of Skin Therapy. (2013). Common types of typical formulations. Retrieved November 12, 2103, from http://www .dermweb.com/therapy/overview.htm Public Health Advisory. (2007, June 2). Life-threatening side effects with the use of skin products containing numbing ingredients for www.psnjournalonline.com
27
Copyright © 2014 American Society of Plastic Surgical Nurses. Unauthorized reproduction of this article is prohibited.
PSN-D-13-00041.indd 27
2/14/14 9:57 PM
Pharmacology Department
cosmetic procedures. Retrieved December 3, 2013, from http:// www.fda.gov/Drugs/DrugSafety/PostmarketDrugSafetyInfor mationforPatientsandProviders/DrugSafetyInformationfor HeathcareProfessionals/PublicHealthAdvisories/ucm054718.htm Sobanko, J. F., Miller, C. J., & Alster, T. S. (2012). Topical anesthetics for dermatologic procedures: A review. Dermatologic Surgery, 38(5), 709–721.
28
www.psnjournalonline.com
Topical anesthetics—lidocaine, benzocaine, tetracaine. (2009, July 9). Complementary compounding services. Retrieved November 22, 2013, from http://www.custommedicine.com.au/healtharticles/topical-anesthetics Windle, M. L., & Kulkarni, R. (2013, April 25). Topical anesthesia. Retrieved November 20, 2013, from reference.Medscape.com/ article/109673-overview#a1
Volume 34 Number 1 January–March 2014
Copyright © 2014 American Society of Plastic Surgical Nurses. Unauthorized reproduction of this article is prohibited.
PSN-D-13-00041.indd 28
2/14/14 9:57 PM
Customizing Compounded Topical Anesthetic Preparations Sahar Whelan, RPh, BScPhm, MScPhm Souha Mourad, RPh, BScPhm
T
he administration of topical anesthetics to control pain associated with cosmetic procedures avoids the risks associated with infiltrative local anesthesia injections and the associated pain from the injections. The ideal topical anesthetics would provide complete anesthesia following a simple pain-free application, not contain narcotics or controlled substances, and be safe to use (http:// www.custommedicine.com.au/health-articles/topicalanesthetics). The most popular local anesthetics used include lidocaine, benzocaine, tetracaine, and prilocaine (Topical Anesthetics, 2013, http://www.custommedicine .com.au/health-articles/topical-anesthetics). Many dosage forms such as gels, sprays, creams, ointments, and patches provide the clinical response with precise options for application under various circumstances (Windle & Kulkarni, 2013). The demand for professional compounding of customized preparations has increased as patients and health care professionals realize that the limited number of strengths and dosage forms that are commercially available do not meet the needs of each individual. The following is a discussion on the customization of topical anesthetic preparations, which may lead patients to having a better response and receiving “just what the doctor ordered” (http://www.custommedicine.com.au/health-articles/ topical-anesthetics). To customize the local anesthetic, one must not only understand the pharmacology of local anesthetics but Sahar Whelan, RPh, BScPhm, MScPhm, graduated from the University of Toronto, Ontario, Canada, in 1988 with a bachelor’s degree in pharmacy and in 1990 with a master’s degree. She worked in the Retail and hospital sector; being the Director of Infusion Pharmacies, she specialized in compounding intravenous, nutrition, oral, dermatological, and sterile ophthalmic products. Souha Mourad, RPh, BScPhm, is a registered Pharmacist in the Province of Ontario, Canada and has more than four decades of pharmacy experience in the Middle East and Canada in areas such as hospital and retail. She specializes in the sterile and nonsterile compounding of various products for patients who require specific products not commercially available. She focuses on the customized needs of the patient. The authors report no conflicts of interest. This article was written with strict ethical adherence and no funding was obtained to write the article. Address correspondence to Sahar Whelan, RPh, BScPhm, MScPhm, Concord Specialty Pharmacy, 2180 Steeles Avenue W, Unit 4, Concord, Ontario, Canada L4K 2Z5 (e-mail: [email protected]). DOI: 10.1097/PSN.0000000000000024
Plastic Surgical Nursing
understand the patient as well. This enables the anesthetist to predict the potency, speed of onset, duration of action, and safety of a specific drug in a given clinical situation. This maximizes the opportunity for safe and effective use of local anesthesia.
PHARMACOLOGY OF LOCAL ANESTHETICS The definition of a local anesthetic is “a drug which reversibly prevents transmission of the nerve impulse in the region to which it is applied, without affecting consciousness” (Edgcombe & Hocking, 2005). The structural classification of local anesthetics relates to their lipid-soluble hydrophobic aromatic group or the charged, hydrophilic amide group. This bond determines the class and may be amide or ester. The amides include lidocaine, bupivacaine, and prilocaine. The esters include cocaine, benzocaine, and amethocaine. Esters’ metabolism results in the production of para-aminobenzoate (PABA) that is associated with allergic reactions. But the amides very rarely cause allergic phenomena and that’s why amides are more commonly used than esters. To quickly determine whether an anesthetic agent is an ester or an amide, note whether the generic name contains the letter i once or twice. Esters contain the letter i once in their generic names, whereas the generic names for amides contain the letter i twice (Principles of Skin Therapy, 2013, http://www.dermweb .com/therapy/overview.htm). The pKa of a local anesthetic is a quantitative measure of the strength of an acid in solution or, in the simplest of terms, represents the ability of the drug to cross the lipid cell membrane in a physiological pH of 7.4. The local anesthetics with a pKa closest to pH of 7.4 will reach its target site more quickly. For example, lidocaine (pKa of 7.9) has a faster onset of action than bupivacaine (pKa of 8.1). In addition, it is important to note that infected tissue tends to be a more acidic environment than usual and the pH is reduced significantly so the onset of action of local anesthetics is reduced and the effect is delayed. Consequently, the increased blood supply of the infected tissue will cause more of the local anesthetic to be removed from the area before it can affect the nerve (Edgcombe & Hocking, 2005). www.psnjournalonline.com
25
Copyright © 2014 American Society of Plastic Surgical Nurses. Unauthorized reproduction of this article is prohibited.
PSN-D-13-00041.indd 25
2/14/14 9:57 PM
Pharmacology Department
The Esters are broken down rapidly by plasma esterases to inactive compounds and consequently have a short half-life. Cocaine is broken down in the liver. But ester metabolites are excreted from the kidneys. The amides are metabolized in the liver by amidases. This process is slower so the half-life is longer and repeated doses can cause accumulation. Prilocaine is metabolized outside of the liver as well (Edgcombe & Hocking, 2005). Adrenaline’s vasoconstrictor properties can minimize the vasodilator effect of lidocaine and decrease the rate at which drug is removed from the site of action by absorption in the systemic circulation. In addition, it reduces blood loss from the site by the same mechanism (Edgcombe & Hocking, 2005). Adrenaline may potentially induce adverse effects. Therefore, its use must be carefully considered in patients with heart disease and those patients concomitantly taking β-blockers (Niteen, 2012). Bicarbonate is also added to a local anesthetic to increase the pH of the area when administered and in this way more drug is present in the molecular lipophilic form, which crosses cell membranes easily and hence increases the speed of onset of action (Edgcombe & Hocking, 2005).
TYPES OF FORMULATIONS COMMERCIALLY AVAILABLE Now, we have a better understanding why lidocaine is the local anesthetic most frequently used. It is effective, acts rapidly, and safe and it is uncommon for any allergic reactions. It is available in different formulations; however, the commercial products available (lidocaine 2%, 5% cream and jelly, 4% tetracaine gel) may not be effective in producing sufficient pain block for some cosmetic procedures in many patients. Painless dermal local anesthesia can be achieved with the topical anesthetic Emla. This is a combination of lidocaine and prilocaine and comes in the form of cream or patches. It is particularly useful for numbing areas that require injection, especially in children (Windle & Kulkarni, 2013).
FACTORS TO CONSIDER WHEN CHOOSING A TOPICAL PREPARATION 1. An occlusive vehicle enhances penetration of the active ingredient and improves efficacy. The vehicle may be cooling, drying, emollient, or protective action. 2. Match the type of preparation with the site (e.g., gel or lotion for hairy areas) 3. Ointments and water-in-oil (w/o) creams are less irritating, while gels are irritating. a. Creams are oil-in-water or w/o emulsions 26
www.psnjournalonline.com
b. Ointments are semisolid preparations of hydrocarbons (petrolatum, mineral oil, paraffins, and synthetic hydrocarbons) i. Occlusive effect enhances absorption and improves efficacy ii. Protective film on the skin iii. Greasy and sticky, retains sweat and not suitable in hairy areas or hot weather conditions or in skin prone to folliculitis iv. Contains no water and does not require a preservative c. Pastes are a mixture of powders and ointments i. Addition of powder improves breathability. ii. Addition of powder to change an ointment into a paste increases the consistency of the preparation so it is more difficult to rub off. This is useful when trying to protect an outer area from an irritating preparation. d. Lotion is any liquid preparation in which medications are suspended or dissolved. i. Lotions are easy to apply to large areas. ii. They are suitable for hairy areas and skin prone to acne. iii. Most are aqueous or hydroalcoholic with the small amounts of alcohol added to hasten evaporation of the solvent from the skin surface. e. Gels are transparent preparations containing cellulose ethers or carbomer in water or a water-alcohol mixture i. Gels liquefy on contact with the skin, dry and leave a thin film of active medication. ii. They tend to be drying. iii. Useful in hairy areas. iv. Cosmetically acceptable. Occlusive dressings may be applied to formulations (e.g., DuoDERM, Tegaderm, Saran wrap) to improve absorption. Iontophoresis has been used to improve the effects of topical anesthesia; however, equipment is expensive and bulky and the mild electrical sensation can cause discomfort in patients (Drug Absorption, 2013, http://www.medisca.net/cen/Tips/Drug%20Absorption. pdf). Removing the stratum corneum (outermost layer of the epidermis containing dead cells) with preoperative procedures such as tape, stripping, degreasing with acetone, or laser ablation enhances dermal absorption. Heat can also facilitate anesthetic penetration into the skin (Drug Absorption, 2013, http://www.medisca.net/cen/Tips/ Drug%20Absorption.pdf). Fear of needles and pain can cause anxiety in patients awaiting procedures in the outpatient setting. Application of topical anesthetic before or in place of injection of Volume 34 Number 1 January–March 2014
Copyright © 2014 American Society of Plastic Surgical Nurses. Unauthorized reproduction of this article is prohibited.
PSN-D-13-00041.indd 26
2/14/14 9:57 PM
Pharmacology Department
local anesthetic can help relieve anxiety (Sobanko, Miller, & Alster, 2012). High plasma concentrations of topical anesthetics can cause adverse effects. The application of topical anesthetics to abraded or torn skin can result in excessive exposure. Possible adverse effects include the following: • Burning or stinging at the administration site. • Oral viscous lidocaine may cause systemic toxicity, particularly with repeated use in infants or children. • Central nervous system (CNS) stimulation, such as seizures followed by CNS depression, respiratory depression. This may be absent or minimized when amides like tetracaine are administered. Solutions that contain epinephrine may add to the CNS stimulatory effect. • Cardiovascular: Heart depression resulting in bradycardia, arrhythmias, hypotension, cardiovascular collapse, and cardiac arrest. Local anesthetics that contain epinephrine may cause tachycardia, hypertension, and angina. • Gag-reflex suppression may occur with oral administration. Other adverse effects include transient burning sensation, skin discoloration, swelling, neuritis, tissue necrosis, and sloughing and methemoglobinemia (observed with prilocaine) (Niteen, 2012). The U.S. Food and Drug Administration has issued an advisory regarding the risk of serious adverse effects with the use of topical anesthetics for cosmetic procedures. Life-threatening adverse effects occurred following topical anesthetic application over large surface areas of the body; for some, a plastic occlusive was also applied to enhance absorption. Two women experienced seizures, coma, and death following applying topical anesthetics to their legs with an occlusive dressing before laser hair removal (Public Health Advisory, 2013, http://www.fda. gov/Drugs/DrugSafety/PostmarketDrugSafetyInformation forPatientsandProviders/DrugSafetyInformationfor HeathcareProfessionals/PublicHealthAdvisories/ucm 054718.htm). Drug concentration is expressed as a percentage (e.g., dibucaine 1%, benzocaine 0.5%). Percentage is measured in grams per 100 mL (e.g., 1% is 1 g/100 mL [1000 mg/ 100 mL] or 10 mg/mL). To calculate the mg/mL concentration quickly from the percentage, move the decimal point 1 place to the right, as follows: lidocaine 2% = 20 mg/mL and benzocaine 20% = 200 mg/mL (Windle & Kulkarni, 2013). So based on the knowledge previously discussed, various compounded mixtures have been tested and are utilized in many cosmetic procedures. These compounds help achieve the ultimate goal of “complete anesthesia following Plastic Surgical Nursing
a simple pain-free application” and they are safe to use. You may order these specifically customized for your patients from experienced local compounding pharmacies. LET anesthetic gel—lidocaine, tetracaine, and epinephrine (amide, ester, and vasoconstrictor)—treats pain associated with lacerations and where skin may be broken during regular tattooing. Onset of action is usually 20–30 min after it is applied (Windle & Kulkarni, 2013). BLT gel—benzocaine, lidocaine, and tetracaine (amide and two esters)—is effective when applied prior to laser procedures. It has a rapid onset of action (20– 30 min) compared with 1–2 hr with EMLA cream and it does not require any occlusive dressing (Windle & Kulkarni, 2013). PLT gel—prilocaine, lidocaine, and tetracaine (amide and 2 esters)—may be preferable to BLT gel because there were reported incidences of methemoglobinemia with benzocaine when applied to large areas (Windle & Kulkarni, 2013). Cosmetic laser clinics utilize PLT, LET, BLT, EMLA creams, and patches and other LT (lidocaine/tetracaine) combinations that are specifically formulated for this purpose (http://www.custommedicine.com.au/healtharticles/topical-anesthetics).
SUMMARY Anesthesia in aesthetic procedures is extremely important from both the functional role and also the psychological impact on perception of the procedure by the patient. When there is successful (safe and pain-free) anesthesia for the patient, the experience is pleasant and it is more likely that the procedure will be repeated if warranted. It is important to remember that each individual patient will walk into a cosmetic procedure clinic with different perceptions of pain and comfort. With a solid knowledge of the availability of different anesthetic options, patients’ fears may be alleviated and there will be a chance for a more positive outcome. REFERENCES
Drug absorption—comparison for altered route of administration. (2013). Retrieved November 23, 2013, from http://www .medisca.net/cen/Tips/Drug%20Absorption.pdf Edgcombe, H., & Hocking, G. (2005). Local anaesthetic pharmacology 11/07/05. John Radcliffe Hospital, Oxford, UK. World Anaesthesia Tutorial of the Week. Retrieved November 20, 2013, from http://www.AnaesthesiaUK.com/WorldAnaesthesia Niteen, D. V. (2012). Local anesthesia for cosmetic procedures, clinical use of local anesthetics. Retrieved November 23, 2013, from http://www.intechopen.com/books/clinical-use-of-localanesthetics/anesthesia-for-cosmetic-procedures Principles of Skin Therapy. (2013). Common types of typical formulations. Retrieved November 12, 2103, from http://www .dermweb.com/therapy/overview.htm Public Health Advisory. (2007, June 2). Life-threatening side effects with the use of skin products containing numbing ingredients for www.psnjournalonline.com
27
Copyright © 2014 American Society of Plastic Surgical Nurses. Unauthorized reproduction of this article is prohibited.
PSN-D-13-00041.indd 27
2/14/14 9:57 PM
Pharmacology Department
cosmetic procedures. Retrieved December 3, 2013, from http:// www.fda.gov/Drugs/DrugSafety/PostmarketDrugSafetyInfor mationforPatientsandProviders/DrugSafetyInformationfor HeathcareProfessionals/PublicHealthAdvisories/ucm054718.htm Sobanko, J. F., Miller, C. J., & Alster, T. S. (2012). Topical anesthetics for dermatologic procedures: A review. Dermatologic Surgery, 38(5), 709–721.
28
www.psnjournalonline.com
Topical anesthetics—lidocaine, benzocaine, tetracaine. (2009, July 9). Complementary compounding services. Retrieved November 22, 2013, from http://www.custommedicine.com.au/healtharticles/topical-anesthetics Windle, M. L., & Kulkarni, R. (2013, April 25). Topical anesthesia. Retrieved November 20, 2013, from reference.Medscape.com/ article/109673-overview#a1
Volume 34 Number 1 January–March 2014
Copyright © 2014 American Society of Plastic Surgical Nurses. Unauthorized reproduction of this article is prohibited.
PSN-D-13-00041.indd 28
2/14/14 9:57 PM
