Keywords
Topical preparationsRetinoidTretinoinChemical peelCleanserTonerMoisturizerAcneAcne preparationsOTC productsSkin care5.1 The Skin and Topical Preparation Properties
The skin is the largest and heaviest organ of the body. It averages 20 square feet and weighs about 9 lbs (Jablonski 2006). The skin has many functions including regulating body temperature, providing protection from environmental toxins and harmful ultraviolet radiation, acting as a barrier to prevent water loss, inhibiting invasion of foreign substances, and providing an immune defense from potential threats (Nicol 2016; Habif 2016).
The goal of topical preparations is to maintain and restore the highest level functions of the skin barrier. Functions of aesthetic practice are to rejuvenate the skin, repair damage that has occurred from UV radiation, prevent damage from environmental forces, and treat acne. The goal of aesthetic practice is to assist the patient in achieving their desired appearance and the healthiest skin possible.
Absorption rates of topical preparations also vary depending on anatomic site. Skin thickness and composition vary according to the area of the body. For example, eyelids and mucous membranes have faster absorption rates compared to palms of the hands or soles of the feet (Habif 2016). The skin on the palms of the hands and the soles of the feet have a thicker stratum granulosum layer of the epidermis than other areas of the body and this accounts for the difference in appearance and absorption rate (Nicol 2016). For a more detailed description of the anatomy of the skin, please see Chap. 2.
The characteristics of the skin on different body areas will influence not only absorption rates but the efficiency, effectiveness, and possible side effects of topical preparations. The absorption rate of transdermal medications is affected by the thickness of the stratum corneum and this can vary on different areas of the body (Brown and Langer 1988). For example, tretinoin, a prescription topical medication for acne, is available in strengths of 0.025–0.1% and can be used on areas including the face, chest, back. However, the skin on the face compared to the chest can have different thicknesses (Nicol 2016; Habif 2016; Brown and Langer 1988). The face can have a thicker stratum corneum than the chest on certain individuals and the use of 0.1% strength tretinoin on the chest could cause more intense side effects than if the same strength was used on the face. Thus, providers must consider application site and intention of application for each individual and provide individualized dose and duration of the topical prescribed.
5.2 Vitamin A/Retinoids
Vitamin A/retinoids (tretinoin) and their derivatives are frequently used in treating acne, photoaging, hyperpigmentation, actinic keratosis , wrinkles, and to enhance percutaneous absorption of other topical agents such as hydroquinone (Habif 2016; Marson and Baldwin 2019; Leyden et al. 2017; Thielitz et al. 2008). Tretinoin has multiple trade names, i.e., Retin-A®, and is available in cream, lotion, and gel and is used as a treatment for wrinkles, rough skin, and hyperpigmentation (Topical tretinoin 2019).
The onset of action of tretinoin for acne treatment is 2–8 weeks (Habif 2016). Fine lines and wrinkles typically respond within several months with consistent tretinoin use (Topical tretinoin 2019). Some additional benefits of tretinoin are improved skin turgor, improvement of all major components of the skin, and improved skin color due to improved skin circulation (Haney 2016; Thielitz et al. 2008; Duteil et al. 2017). Additionally, patients who have more severe photodamage have been shown to have superior results compared to those with minimal photodamage (Kligman et al. 1986). More importantly, abnormal skin cells, such as actinic keratosis , have been shown to proliferate toward becoming normal cells with consistent use of tretinoin (Kligman et al. 1986). This finding supports the notion that reversal of actinic keratosis, potentially cancerous cells, and sun damaged skin is attainable with tretinoin use.
The mechanism of action of tretinoin is not well understood but it has been shown to initiate increased cell turnover in normal follicles and comedones (Thielitz et al. 2008). This action benefits acne sufferers because it reduces cohesion between keratinized cells and prevents the build-up of trapped skin cells under the skin. These trapped cells lead to the inflammatory response of acne lesion formation (Habif 2016). In addition, tretinoin appears to disrupt the surface epithelium and allow better penetration of other substances such as hydroquinone or benzyl peroxide (Fulton et al. 1974). For these reasons, tretinoin is often combined with various other topical preparations.
Side effects of tretinoin include erythema, skin peeling, dryness, edema, stinging sensation, extrusion of comedones, and the prevention of new comedone formation (Habif 2016; Haney 2016; Thielitz et al. 2008). There is also an increased risk of sunburn due to the thinning of the stratum corneum while using tretinoin (Habif 2016). Patients may experience increased stinging or sensitivity to some previously used topical preparations after they start using tretinoin (Habif 2016). These patients should be advised to avoid using any products that increase stinging such as products with preservatives or fragrance. Patients should also be instructed to avoid applying tretinoin around the lateral and medial canthi of the eyes, oral commissures, angles of the nose, and mucous membranes because it may cause epidermal injury (Habif 2016).
1. Dryness—the application of non-irritating moisturizer 30 minutes after application of the retinoid at night and continually applying moisturizer throughout the following day if desired |
2. Irritation—start with a weaker dose of the medication and apply every other night or twice a week for a 2–4 weeks until tolerance has improved, then increase until application occurs every night |
3. Redness/stinging—sun avoidance is strongly advised. Application of sunscreen of 30–50 SPF and the use of physical UV blocks such as a hat, sunglasses, and clothing are necessary to decrease the extent of sun exposure and side effect |
4. Chemical or physical scrubs increase the chance of irritation and are not recommended while using stronger versions of prescription tretinoin |
An important role of the aesthetic practitioner is to educate the patient on risks, benefits, and side effects of medications, including topical preparations. Management of patient expectations regarding treatment results and the time necessary to notice improvement in the skin condition is also important. Providing thorough explanation and the opportunity for the patient to ask questions ensures best outcomes and adherence to the prescribed regimen (Habif 2016).
5.3 Skin Lighteners
5.3.1 Hydroquinone
Hydroquinone is a commonly used ingredient in creams and lotions to lighten the skin, decrease pigments from sun exposure, and treat melasma (Nordlund et al. 2006). Currently, it remains the gold standard for treating hyperpigmentation and melasma (Tse 2010; Draelos 2007a). Controversies in hydroquinone use arose when a study using rats demonstrated that large amounts of ingested hydroquinone were associated with development of tumors. However, there are no reports of tumor formation in humans when used as a topical preparation (Nordlund et al. 2006; Vanaman Wilson et al. 2017; Levitt 2007). Consequently, some regulatory agencies previously raised concern over its use but it is now considered safe and effective for topical human use in approved doses (Levitt 2007; Torok 2006).
Hydroquinone works by blocking the tyrosinase catalyzed conversion of tyrosine into melanin. Tyrosinase is the enzyme involved in the early stages of melanin formation (Palumbo et al. 1991). Further, the use of tretinoin in combination with hydroquinone provides a more efficacious and tolerable effect than either drug used alone (Draelos 2007a; Hsieh et al. 2017). The results for the patient include lighter brown spots, fewer hyperpigmented areas, improvement in photodamage, and smoother looking skin (Vanaman Wilson et al. 2017). Most prescription skin lightening regimens include daily application of hydroquinone either alone or in combination with other medications or substances to be used for a specified amount of time. Practitioners who prescribe skin lightening medications often recommend a drug holiday although the literature does not confirm or refute this practice.
Side effects of hydroquinone are mild for most people and include dryness, irritation, peeling, erythema, and/or stinging or burning (Vanaman Wilson et al. 2017). Sun avoidance is crucial when using hydroquinone for hyperpigmentation because the effects of sun exposure contribute to the darkening of pigments. Implications of UV rays and infra-red exposure from sunlight should be communicated to the patient and discussed during the initial consultation for treatment (Duteil et al. 2017). Patients might report they spend time outdoors or enjoy activities where sun exposure is virtually guaranteed and they are resistant to avoiding sun exposure.
Commitment to sun avoidance is an important component of the skin lightening regimen and should be emphasized to the patient. Sun exposure while attempting to reverse hyperpigmentation caused from UV and infra-red influence is counter-productive and may worsen the side effects of prescribed medications (Habif 2016). Patient commitment, skin condition, and level of side effect tolerability can be useful to guide practice and recommend appropriate regimens for patients.
5.3.2 Azelaic Acid
Azelaic acid (AA) is a dicarboxylic acid synthesized by the fungus, Malassezia furfur, and AA is commonly used to treat melasma, rosacea, and acne (Fitton and Goa 1991; Ball Arefiev and Hantash 2012). Malassezia furfur is associated with the hypopigmented macules seen in tinea versicolor (Ball Arefiev and Hantash 2012). Azelaic acid has been increasingly used as a skin lightener because of concern over the side effect profile of hydroquinone and tretinoin; AA causes less skin irritation than hydroquinone and tretinoin (Draelos 2007a, 2009). However, AA has slightly less efficacy in the treatment of hyperpigmentation than hydroquinone but can be better tolerated in patients with sensitive skin because there is only a short lived stinging sensation (Draelos 2007a). Azelaic acid can also safely be used in combination with other skin lightening preparations for additional pigment improvement (Fitton and Goa 1991).
Azelaic acid has a similar mechanism of action as hydroquinone as it interferes with tyrosinase activity, but in addition, AA appears to interfere with DNA synthesis because of a specificity for abnormal melanocytes (Draelos 2007a). Due to this affinity for abnormal melanocytes, AA has been used to suppress the progression of lentigo maligna to lentigo maligna melanoma (Fitton and Goa 1991). Azelaic acid has an excellent safety profile and can be a viable option to hydroquinone or tretinoin for skin lightening (Draelos 2007a).
5.4 Selected Skin Care Products: Cleansers and Moisturizers
5.4.1 Cleansers
Soap has been used for thousands of years and is the oldest surfactant. Surfactants are defined as the alkali salt of fatty acids with a pH of 9.5–10 (Friedman and Wolf 1996; Draelos 2018a). Synthetic soaps vary in composition, surfactant types, and pH. Cleansers emulsify dirt, oil, environmental debris, and microorganisms on the skin surface. During cleansing, the interaction between the cleanser, the moisture skin barrier, and skin pH plays a role in removing these elements (Kuehl et al. 2003).
The most common cleanser formulations are composed of synthetic detergents, known as syndets, which is a combination of the words synthetic and detergent (Draelos 2018a). These cleansers possess a neutral to slightly alkaline pH resulting in less removal of the protective skin barrier because the related pH of syndets more closely resembles the pH of the skin. Soaps typically have a pH of 9–10, while syndets have a pH of 5.5–7, closer to natural skin pH (Korting and Braun-Falco 1996).
Cleansers are an important part of the skin care regimen because they remove superficial debris and, therefore, can help prevent comedones and large pores. The pH of the skin is considered to range from 4.2 and 5.9 and it is generally believed most people benefit from using acidic cleansers (Kuehl et al. 2003; Korting and Braun-Falco 1996). Cleansers contain ingredients that work in different ways. Depending on the skincare concern, patients choose cleansers based on their skin care goals, thus one patient might choose ingredients for oily skin, and others for dry skin.
Water | |
Surfactants | Break up debris found on the skin |
Moisturizers | (emollients and humectants)—Added to cleansers to mitigate the effect of the acidity and to maintain skin barrier |
Binders | Stabilize the product |
Lather enhancing substances | To provide foam |
Preservatives | All cleansers must contain preservatives to prevent the growth of microorganisms |
Fragrance | Can be a source of irritation or reaction in some patients |
Dyes or pigments | Can be found in some products, gives color |
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