Topical Anaesthetics & Cosmetic Procedures

Important: This is not a how to guide it is a general discussion of the potential risks associated with the use of topical anaesthetics. The regulatory focus of this article is that which exists in Australia however the general principles can also be considered in other regulatory domains. I am happy to add to links that I have provided in Appendix 2 for regulatory information in other locations if they are both supplied and requested by others in different countries.

Whilst there are some commercial preparations available on the market many have significant drawbacks associated with their use prior to or during minor cosmetic procedures due to a variety of factors such as;
 

• A high pH (alkaline) e.g. Emla cream pH 9.0-9.2, a product with a pH much above 8.0 may pose significant risk to the sight of the client/patient if used on the face anywhere near the eye¹ and may also be disruptive to cellular functioning (healing) of the dermis and supporting structures if used prior to skin penetration procedures. It is also unclear what effect an alkaline topical cream may have on tattoo pigments if used prior to a cosmetic tattoo procedure though it does seem plausible that it could cause a colour change to the pigment due to chemical interaction with some ingredients contained within the various pigments.
   

A pH scale which is most often described as a range between 0-14 is a logarithmic measurement of hydrogen ions H+ and the scale provides us the indication of acidity or alkalinity of a liquid, a pH of 1 having very toxic acidity (acid) and a pH 14 having very toxic alkalinity (caustic), distilled water is neutral with a pH around 7.

Because it is a logarithmic scale each whole number increment above or below 7 is; 10 times as acidic (when below 7), or 10 times as alkaline (when above 7) e.g. a pH of 3 is 10 times as acidic as a pH of 4, and a pH of 12 is 10 times as alkaline as a pH of 11. Each incremental change of 0.1 on the pH scale represents about a 26% increase in the acidity or alkalinity of the solution as you move away from the neutral point at 7.0 on the scale.

As you can see small changes on the pH scale have dramatic changes in the potentially damaging acidity or alkalinity of a liquid and the human eye is extremely sensitive to even small changes in pH, for this reason a topical anaesthetic that is used anywhere on the face should be in the pH safe region and definitely not outside of the irritant zone indicated below. There are cases within the medical literature where chemical injury to the eye has occurred due to the use of alkaline topical anaesthetics near the eye¹.

Even if a topical anaesthetic is pH safe, if it is to be used on the face then great care should be taken to ensure the anaesthetic does not enter the eye because if the eye surface becomes anaesthetised then a corneal abrasion could easily occur inadvertently without the patient becoming aware, that is until the anaesthetic wears off!

pH Scale Acidic danger zone for the eye Irritant Zone ◄ Safe  Zone Irritant Zone ► Alkaline danger zone for the eye 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Super Acids ◄ -- Very Acidic (toxic to eye)   Neutral   (toxic to eye) Very Alkaline --► Super Bases Battery Acid 0.3 Vinegar 2.8 Lemon Juice 2.2 Orange Juice 4.7 Milk 6.7 Tears 7.5 Blood 7.35-7.45 Sea Water 7.5-8.4 Baking Soda 8.4 Ammonia 11.5 Bleach 12.6 Caustic Soda 13.5 Floor Stripper 13

• Some commercial preparations contain the ingredients Prilocaine and Benzocaine. A review published by the International Anesthesia Research Society in 2009² found that of 242 reported cases of anaesthetic related Methemoglobinemia found within the medical literature since the year 2000, 105 were related to Benzocaine used alone, 44 were related to Prilocaine used alone, and only 10 were related to Lidocaine used alone, just 1 was related to Tetracaine. The conclusion of the review was that "Benzocaine should no longer be used".
  
  It is reasonable to conclude from the review that there is significantly less risk of a client/patient developing Methemoglobinemia with preparations containing Lidocaine and or Tetracaine than with preparations containing Prilocaine and or in particular Benzocaine.

Acquired methemoglobinemia is an uncommon though potentially life threatening blood disorder where an abnormal amount of the oxygen-carrying molecule haemoglobin builds up in the blood. In some of those cases the haemoglobin is unable to carry oxygen effectively to body tissues causing the patient severe hypoxic distress (low oxygen to the bodies cells).

Symptoms of methemoglobinemia may include a bluish or brownish colouring of the skin, headache, fatigue, shortness of breath, loss of energy, dysrhythmias (irregular heart beat), seizures, potentially leading to coma and death if untreated. Whilst this condition is uncommon it seems prudent to avoid use of the anaesthetics prilocaine and benzocaine which appear to have the greatest risk of triggering the condition². In addition it has been shown that Lidocaine-Tetracaine eutectic preparations are just as effective in skin anaesthesia as lidocaine-prilocaine³ commercial preparations.

The application of dermal preparations containing lidocaine have been shown to reduce discomfort of the client/patient during a variety of minor procedures⁴ including mammography⁵. However it should also be borne in mind that there are risks associated with the use of topical anaesthetics such as lidocaine even in low concentrations if they are used over too large an area, or in excessive amounts, or for prolonged durations.

In 2009 The Food and Drug Administration of the United States Department of Health And Human Services cautioned against using topical anaesthetics in too great an amount, over too large an area, applying to irritated or broken skin, or using wraps or heating pads to increase skin absorption⁶. The caution issued by the US FDA cited concern due to reports of deaths following similar use of topical anaesthetics by women preparing for laser hair removal procedures.

For the above reasons it is essential to ensure that topical anaesthetics are used sparingly and they are not applied to large areas of skin nor to areas where skin conditions exist, particularly if the surface of the skin is broken down. For example it would be contraindicated to apply a topical anaesthetic to an area of ulcerated, blistered or abraded skin as absorption may be much faster and the anaesthetic has a greater chance of entering the blood stream potentially affecting the client’s heart and brain as well as other internal organs.

I cannot stress strongly enough the risks associated with misusing or overdosing a client/patient with a topical anaesthetic, if substances such as lidocaine enter the blood stream they can disrupt the normal; rate, rhythm, and co-ordination, of the hearts electrical system and its muscle function. Ultimately that could lead to significant slowing of the heart, dangerous hearth arrhythmias, seizures, cardiac arrest (the heart stopping altogether) and potentially death.

Prior to purchasing and using anaesthetic products you should ensure that you are;

1) familiar with and in compliance of the Therapeutic Goods Act 1989 and the current Poisons Standard (see appendix 2). If in doubt contact the Therapeutic Goods Administration or if you provide services outside of Australia consult with your local health regulatory authorities.

2) familiar with and in compliance of your local state or territory acts and regulations (see appendix 2). If in doubt always consult with your local health regulatory authorities.

3) familiar with the active ingredients within the products, the safe use of the product and any potential side effects (see appendix 1). If in doubt consult with an experienced pharmacist and medical practitioner.

4) following the manufacturers safety precautions (see appendix 1).

Efficacy of Topical Anaesthetics

Contrary to popular belief the concentrations of a topical anaesthetics active ingredients are not the sole factor in determining the efficacy of the product. There are several factors that will determine the efficacy of a topical anaesthetic product;

• individual types and concentrations of the anaesthetics in the product.
  
  
• The melting point of the anaesthetics.
  
  
• Compounds of anaesthetics - Some compounds create a 'eutectic mixture' with a lower melting point when combined than the melting point of the individual ingredients, which may tend to improve the absorption of the final product at normal skin temperature.
  
  
• The type of carrier - water based gel, cream, a PLO (Pluronic Lecithin Organogel) a mixture of oil and water that thickens to form a gel, or a liquid. The type carrier that is used is very important, a good carrier will assist in epidermal transference of the active ingredients. It is also important to carefully consider the nature and type of carrier if the product is to be used prior treatments that involve laser therapy. Obviously a carrier that may ignite (alcohols) or fry (oils) the skin during the application of laser are potentially very dangerous. As you can see a topical anaesthetic should be chosen as purpose specific, a product that is suitable for one procedure may be dangerous if used for another type of procedure.
  
  
• The pH - The final acidity/alkalinity of the anaesthetic will not only affect the safety of the product it can also affect skin absorption.
  
  
• The thickness/hardness/dryness of the skin - thicker, drier, or harder epidermal skin will take longer to penetrate. However the use of abrading devices prior to the application of topical anaesthetics is contraindicated due to the potential to create raw skin that may increase deeper absorption and ultimately blood serum levels.
  
  
• Natural skin oil - oily skin will tend to repel anaesthetic creams.
  
  
• The duration of application - too short a period and the anaesthetic has not had time to work, too long and it may have worn off before the treatment commences. Different anaesthetics will have different durations of peak efficacy therefore it is important to know the 'Time Course' of your products before using them.
  
  
• The Time Course of the anaesthetic compound - in pharmacokinetics this is often referred to by the acronym LADME or ADME for the drug; Liberation - Absorption - Distribution - Metabolism - Excretion, with topical anaesthetics the 'Liberation' & "Absorption' time frames should not be ignored they are the periods of time required for the active ingredients to be yielded in a form where absorption can occur and the actual time frame for absorption. Some topical anaesthetics are actually solids suspended in the carrier which only become liquids that are capable of absorption once they are applied to the skin and reach normal skin temperature (the melting point).
   
  For this reason a client/patient who is in or has just come from an extremely cold environment may protest that a topical anaesthetic has not worked if you have not provided sufficient time for their skin to warm up naturally before the anaesthetic is applied.
   
  Once absorption has occurred the distribution phase (achieving dermal anesthetisation) for topical anaesthetics will be rapid and there will be a window of peak efficacy for each individual product.
  
  
• The total area of skin that anaesthetic is applied to - smaller areas may actually be easier to achieve effective anaesthesia than larger areas. If possible large areas should always be segmented and treated a small segment at a time in successive sessions with at least 24 hours between sessions, so as to reduce the risk of causing a toxic blood serum level that could occur when treating large area of skin even if you are using products containing low concentrations of anaesthetic.
  
  
• The sensitivity of the body part involved.
  
  
• The pain threshold of the client/patient.
  
  
• Pre/co-existing pain - existing medical complaints/conditions that cause pain will have the tendency to increase sensitivity to any new sources of pain and the client/patient may also exhibit reduced efficacy for pain relief if they have been on long term analgesia.
  
  
• Women who are menstruating - may have a general heightened sensitivity to pain.
  
  
• The mental state of the client/patient - feeling rushed, being hungry/thirsty, needing to go to the toilet, being anxious, stressed or emotionally upset will all tend to heighten the client/patients sensitivity to pain.
  
  
• The technique and manner of the technician - as with any procedure a technician who is both skilled and who projects calm confidence when interacting with the client/patient will help to reduce their overall anxiety about the intended procedure.
  

Do not underestimate the benefits of cool/cold pads/packs when used soothe pain receptors during and after procedures, sometimes the application of cold can be more effective than a topical anaesthetic. If used correctly, the application of cool/cold also has the added benefit of reducing swelling and bleeding during invasive procedures.

 Caking/Heating Topical Anaesthetics

You may have seen examples of topical anaesthetics being applied in a thick layer to the skin surface. I stress that caking of topical anaesthetics does not improve the efficiency of the product for anaesthetisation of the dermis, it does however substantially increase the risk of absorption of a dangerous amount of anaesthetic into the blood stream.

It needs to be born in mind that the purpose of a topical anaesthetic is anaesthetisation of the dermis, which in most cases is only a fraction of a millimetre below the skin surface, you are not trying to cause penetration into the hypodermis/blood stream, so don't cake it on!

You may have also seen examples of anaesthetics being warmed with external heating sources such as hot packs or plastic wraps or even ultrasonic stimulators. External heating and use of ultrasonic stimulators will cause blood vessels within the skin to dilate increasing transfer of anaesthetics into the blood stream.

A well made topical anaesthetic will easily melt and absorb at normal skin temperature therefore there is no additional benefit being gained by using these methods other than perhaps achieving anaesthetisation a few seconds/minutes sooner. But to save those couple of minutes you substantially increase the risk of absorption of a toxic amount of the product into the clients/patients blood stream, so don't risk using external heating or ultrasonic stimulators!

 Caution with Clients with low Body Weight & Both the Young & the Elderly

You should be more cautious with the use of topical anaesthetics with clients/patients who have a low body weight this is because those with lower body weight will potentially develop a toxic blood serum level of anaesthetic quicker than clients with larger body weights, this is a due to the dose/Kg relationship.

The young client/patient may also reach a toxic blood serum level quicker than an adult due to their smaller body mass and also due to metabolic differences that can be particularly potent with some ultra-rapid metabolizers.

The elderly may also be at increased risk of potentially reaching a toxic blood serum level but for different reasons, as we age our heart rate tends to become naturally slower, we are more prone to hypo/hypertension and our hearts electrical conduction may become more susceptible to interruption by anaesthetics which can lead to the dangerous conditions of heart block, extreme bradycardia (slowing of the heart rate) or cardiac arrest. Also the liver and kidneys may be less efficient at breaking down and excreting anaesthetics meaning that lower doses may reach higher serum concentrations and have longer systemic duration than in the younger client/patient.

The Source of Topical Anaesthetics

There are many places on the internet who are supplying topical anaesthetics such as tattoo equipment suppliers, 'quasi' medicine suppliers, cosmetics suppliers, permanent makeup suppliers etc. I will be blunt and state that I have no doubt that some of those sites are supplying anaesthetics illegally.

Within Australia in most circumstances the only legal source of supply of a topical anaesthetic (in a percentage concentration that is at all likely to be effective) is a licensed pharmacist. Importing anaesthetics from overseas opens a whole new can or worms because you may potentially breach both the therapeutic goods act and customs regulations at the same time. Also many internet suppliers appear to offer little or no information about the concentrations of active ingredients within their product and virtially no information about the safe use of the product.

If an client/patient had an adverse event involving the use of a topical anaesthetic that was obtained illegally it is highly likely that the service providers professional indemnity insurance would deny their insurance cover, in fact most policies have specific clauses denying liability if there have been any breaches of health regulations.

For the above reasons in my view a service provider would be extremely foolhardy to obtain and use topical anaesthetics from any source other than from a licensed pharmacist and in full compliance with the applicable acts and regulations.

Appendix 1

General Safety Precautions

Once again I stress this is not a how to guide it is merely a general discussion about some of the general safety precautions that should be considered by an appropriately qualified service provider before using any topical anaesthetic. The number one point here is that topical anaesthetics should only be used by persons who have been trained by a qualified health service provider and in circumstances that are in compliance with the law in your location.

Anaesthetic products should always be used sparingly in the lowest concentrations and quantities possible, applying a thin smear (at least 15-20 mins prior to a procedure) is all that will be required in most circumstances. Caking on large quantities is not likely to improve the effectiveness of topical anaesthetics and doing so may be dangerous.

01) Ensure the client/patient does not have any medical condition that may preclude the use of any of the products ingredients. If in doubt always refer the client/patient to their regular medical practitioner for additional approval/supervision prior to a procedure.  Conditions where additional medical review and approval should be sought may include but are not necessarily limited to;

• Any heart condition or pacemaker or if the client/patient has high or low blood pressure.
  
  
• Any condition or disease of the kidneys or liver.
  
  
• Any bleeding disorder or if taking any anticoagulants (blood thinning medications).
  
  
• Any history of a blood dyscrasias (blood disorder).
  
  
• Any personal or family history of Methemoglobinemia.
  
  
• Any history of epilepsy or seizures.
  
  
• Any major medical condition where any doubts over safety exist.
  
  
• Any skin disease or disorder near the area to be treated or any diffuse (widespread) skin disorder.
  
  
• Serious allergies to any substance especially if hospitalisation has ever been required and particularly if asthma was involved.
  
   

02) Never apply anaesthetics on any woman who may be pregnant nor if they are breast feeding.

03) Ensure the client/patient does not have any allergy or sensitivity to any of the active/inactive ingredients in the products.

04) Ensure you are not using an excessive quantity nor using the anaesthetics over too large a skin area.
 

• The quantity and size of skin area for safe use will depend on the type and concentration of topical anaesthetic⁴, and the age and health status of the client, if in doubt always consult with client’s regular medical practitioner.
  
   

05) Never use any products containing epinephrine (adrenaline) near the eye, on fingers, toes, penis, earlobes, nose, nor inside the mouth.

06) Do not use any anaesthetics in the eye nor inside the mouth and do not permit the client/patient to swallow any of the product.

07) Do not apply any anaesthetics to skin that is diseased, damaged or broken down, e.g. not over eczema, psoriasis or skin abrasions.

08) Do not apply occlusive dressings such as glad wrap over anaesthetics products and do not apply external sources of heat or ultrasound to increase absorption.

09) Be extra cautious with the use of anaesthetics on any person below the age of 16 or above the age of 60, consulting with their doctor again is always prudent.

10) Be extra cautious with the use of topical anaesthetics with clients/patients with low body weight e.g. below 55kg.

11) Wear good quality protective latex or vinyl gloves when handling anaesthetics and always avoid contact with product onto your own skin.

12) Do not provide a client/patient with topical anaesthetic products to take away with them after a procedure.

13) Observe the client/patient for signs of adverse side effects during and after the application of any anaesthetic product.

14) Store anaesthetics in a cool dry location away form direct sunlight as per the products recommended storage instructions and discard according to the manufacturers expiry and disposal instructions.

15) Ensure you are in full compliance with the the Therapeutic Goods Act and your local State / Territory Health Act as well as the policies of your employer.

Serious Adverse Side Effects

This list is by no means comprehensive however the client/patient should seek medical attention if any of the following side effects are experienced or observed after application of any form of anaesthetic products.
 

• Abnormally constricted or dilated pupil.
  
  
• Local skin irritation or rash.
  
  
• Generalised bluish or brownish discolouration of the skin.
  
  
• Light headedness or dizziness.
  
  
• Loss of energy.
  
  
• Tremors, anxiety, confusion, fainting or seizures.
  
  
• Headache, nausea or vomiting.
  
  
• Tingling around the mouth.
  
  
• Blurred vision.
  
  
• Irregular heart-beat or much slower or faster than normal heart-beat/pulse.
  
  
• Difficulty breathing or sudden onset of a cough.

Appendix 2

Links for Various Acts & Regulatory Authorities
 

Australia

Therapeutic Goods Administration

Therapeutic Goods Act 1989

Poisons Standard

Australian Capital Territory
Medicines, Poisons and Therapeutic Goods Act 2008

New South Wales
Poisons and Therapeutic Goods Regulation 2008

Northern Territory
Poisons & Dangerous Drugs Act

Queensland
Health (Drugs and Poisons) Regulation 1996

Tasmania
Poisons Act 1971

South Australia
Controlled Substances (Poisons) Regulations 1996

Victoria
Drugs, Poisons and Controlled Substances Act 1981

Western Australia
Poisons Act 1964

Some of my References

1. Eaglstein, NF. Chemical injury to the eye from EMLA cream during erbium laser resurfacing. Dermatol Surg. 1999 Jul;25(7):590-1.
2. Guay, Joanne. Methemoglobinemia related to local anesthetics a summary of 242 episodes. Anesthesia and analgesia 838 Vol. 108, No. 3, March 2009: 1526-7598.
3. Ohzeki K, Kitahara M, Suzuki N, Taguchi K, Yamazaki Y, Akiyama S, Takahashi K, Kanzaki Y. Local anesthetic cream prepared from lidocaine-tetracaine eutectic mixture. Yakugaku Zasshi. 2008 Apr;128(4):611-6.
4. Carruthers, J. Alastair; Carruthers, Jean D.A.; Poirier, Judith; Oliff, Heather S.; Mordaunt, Julie; Schreiber, William E. Safety of Lidocaine 15 % and Prilocaine 5 % Topical Ointment Used as Local Anaesthesia for Intense Pulsed Light Treatment. Dermatologic Surgery 36 (7): 1130-1137, 2010.
5. Lambertz CK, Johnson CJ, Montgomery PG, Maxwell JR. Premedication to reduce discomfort during screening mammography. Radiology. 2008 Sep;248(3):765-72. Epub 2008 Jul 22.
6. Toigo, Theresa. US Food and Drug Administration Topical Anaesthetics Stakeholder Letter January 16, 2009

Date of most recent revision: 15/03/2013 (mutatis mutandis)
Original publication date: 10/02/2011

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