Prevention of Sun-Induced Skin Disorders (Ch 38, 40)

Prevention Goals

The short-term goals in preventing sun-induced skin disorders are relatively simple: avoid or minimize sunburn, photosensitivity reactions, and UVR-induced or -exacerbated photodermatoses. The expected long-term outcomes are prevention of skin cancer and avoidance of premature aging of the skin.

Broad Spectrum SPF Test

With concern growing about the long-term adverse effects of UVA, the utility of the SPF value in measuring photoprotection from UVA has been questioned. FDA has concluded that both UVA and UVB radiation protection can be assessed effectively by the SPF test in combination with a new broad-spectrum in vitro test. Products that pass the new test will offer higher protection against both UVA and UVB, and they will be labeled as broad-spectrum sunscreens

Safety Concerns

The development of a rash, vesicles (blisters), hives, or exaggerated sunburn after use of the sunscreen product is most likely a sign of either a photosensitivity or allergic reaction

UVC

cause or exacerbate sun-induced skin disorders UVC radiation (wavelength between 200 and 290 nm) is screened out by the ozone layer of the upper atmosphere, little of it reaches Earth; however, UVC is emitted by some artificial sources of UVR. Most of the UVC that strikes the skin is absorbed by the dead cell layer of the stratum corneum

Application

must be applied liberally to all exposed areas of the body and reapplied at least as often as the label recommends. FDA-approved labeling recommends that sunscreens be applied 15-30 minutes before UV exposure and at least every 2 hours thereafter. Reapplication after every episode of swimming, towel drying, or excessive sweating is also recommended

Classification of photodermatoses

4 main categories: immunologically-mediated reactions; drug- or chemical-induced photosensitivity; defective DNA disorders; and photoaggravated disorders.

Skin Protectant Products

A + D Original Ointment -Petrolatum 80.5%; lanolin 15.5%; cod liver oil (contains vitamins A and D) Zinc oxide, Desitin Ointments ---Zinc oxide 20% or 25%; white petrolatum

SPF and UV % Blocked

A product with an SPF of 15 blocks 93% of UVB. Raising the SPF to 30 increases UVB protection to only 96.7%, and an SPF of 40 blocks 97.5%

UVA sunburn

A sunburn involves a number of mediators, including histamine, lysosomal enzymes, kinins, and at least one prostaglandin. These mediators produce peripheral vasodilatation as the UVR penetrates the epidermis; then an inflammatory reaction involving a lymphocytic infiltrate develops. Swelling of the endothelium and leakage of red blood cells from capillaries will also occur. Although the exact mechanism is not fully understood, UVB radiation is believed to produce erythema by first causing damage to cellular DNA. The intensity of the UVB-induced erythema peaks at 12-24 hours after exposure.

UVA

cause or exacerbate sun-induced skin disorders evidence now exists that UVA radiation (wavelength between 320 and 400 nm) is involved in suppression of the immune system and damage to DNA, which result in premature photoaging and skin cancers UVA can produce photosensitivity reactions in patients who have ingested or applied photosensitizing agents. Although approximately 20 times more UVA than UVB reaches Earth at noon (30 times more in winter), erythemogenic activity is relatively weak in the UVA band

Sunburn

caused by too much exposure to ultraviolet A (UVA) and ultraviolet B (UVB) light produced from natural sunlight and by commercial tanning beds and tanning lamps

First-aid Antibiotics

consist of the active ingredients bacitracin, neomycin, and polymyxin B sulfate prevent infection in minor cuts, wounds, scrapes, and burn clean wounds free of contamination have a low infection rate and do not warrant the use of prophylactic antibiotics Topical antibiotic preparations should be applied to the wound bed after cleansing and before applying a sterile dressing. Special caution should be taken when applying these preparations to large areas of denuded skin, however, because the potential for systemic toxicity can increase. Prolonged use of these agents may result in the development of resistant bacteria and secondary fungal infection. If significant signs of improvement are not seen within 7 days, the patient should seek medical attention.

Salicylates

alicylic acid derivatives are weak sunscreens and must be used in high concentrations. They do not adhere well to the skin and are easily removed by perspiration or swimming

Photodermatoses

defined as a heterogenous group of skin disorders that are induced or exacerbated (photoaggravated) by radiation of varying wavelengths. More than 20 disorders are classified as photodermatoses (

UVB

cause or exacerbate sun-induced skin disorders UVB (wavelength between 290 and 320 nm) is the most active UVR wavelength for producing erythema, which is why it is called sunburn radiation. The intensity of UVB radiation reaching the Earth is the highest from 10:00 am to 4:00 pm primary inducer of skin cancer; however, its carcinogenic effects are believed to be augmented by UVA. UVB is also primarily responsible for wrinkling, epidermal hyperplasia, elastosis, and collagen damage. The only true therapeutic effect of UVB exposure is vitamin D3 synthesis in the skin

Benzophenones

group comprises three agents: dioxybenzone, oxybenzone (benzophenone-3), and sulisobenzone (benzophenone-4) primarily UVB absorbers absorbance extends well into the UVA range

Cinnamates

include cinoxate, octinoxate, and octocrylene Cinnamates include cinoxate, octinoxate, and octocrylene. As shown in Table 38-5, cinoxate and octinoxate have similar absorbance ranges and maximum absorbances. Octocrylene, however, has an absorbance range of 250-360 nm, well into the UVA range. Octocrylene is currently found in more commercial sunscreen preparations than it was in the past, possibly reflecting its broader spectrum of absorbance. It is also an effective photostabilizer. Octocrylene can decrease the rate that other sunscreens degrade when they are exposed to sun. It is often combined with other sunscreens to improve their stability

UV Index

scale to rate the amount of skin-damaging UV radiation that reaches the earth's surface at any instance in time index usually given for noon 1-2 Low 3-5 Moderate 6-7 High 8-10 Very high 11+ Extreme

Stage I

minor sunburn only epidermis; superficial consist primarily of reddened, nonblanching unbroken, nonblistering skin increased blood flow begins approximately 4 hours after exposure, peaking between 12 and 24 hours after exposure Avoidance of additional injury and symptomatic relief of pain and fever are usually the only treatment required. heal 3-6 days

Conditions caused/exacerbated by UV exposure

sunburn, premature aging, skin cancers, cataracts, and photodermatoses.

Patient Risk Factors for Development of UVR -Induced Problems

•Fair skin that always burns and never tans •A history of one or more serious or blistering sunburns •Blonde or red hair •Blue, green, or gray eyes •A history of freckling •A previous growth on the skin or lips caused by UV exposure •The existence of a UV-induced disorder •A family history of melanoma •Current use of an immunosuppressive drug •Current use of a photosensitizing drug •Excessive lifetime exposure to UVR, including tanning beds and booths •History of an autoimmune disease

minimal erythema dose

(MED), is used to calculate a sunscreen's SPF. The MED is defined as the "minimum UVR dose that produces clearly marginated erythema in the irradiated site, given as a single exposure." It is a dose of radiation, not a grade of erythema. Generally, two MEDs will produce a bright erythema; four MEDs, a painful sunburn; and eight MEDs, a blistering burn. However, because of variations in thickness of the stratum corneum, different parts of the body may respond differently to the same MED. Furthermore, the MED for heavily pigmented blacks is estimated to be 33 times higher than that for lightly pigmented whites

Natural

Aloe Vera Calendula officinalis Honey

Avoid Sun Exposure

Although unrealistic, complete avoidance of UVR is often the best approach for patients who have the physical characteristics or history listed in Table 38-4. For people who refuse to stay indoors or who must be outdoors for extended periods, wearing protective clothing (e.g., a hat with a 4-inch brim, long pants, and a long-sleeved shirt) should be recommended. In situations in which the patient is unwilling or unable to avoid the sun or to wear protective clothing, the next best choice is to use a sunscreen product

Local Anesthetic Products

Americaine Aerosol -Benzocaine 20% ointment ELA-Max 4% -Lidocaine 4% Dermoplast Pain-Relieving Spray -Benzocaine 20%; menthol 0.5% Dibucaine Topical Ointment -Dibucaine 1% Itch-X Spray/Gel -Pramoxine HCl 1%; benzyl alcohol 10% Solarcaine Aloe Extra Burn Relief Gel/Spray -Lidocaine 0.5% Xylocaine Ointment -Lidocaine 2.5%

Aminobenzoic Acid And Derivatives

Aminobenzoic acid (formerly para-aminobenzoic acid [PABA]), once was the most widely used sunscreen agent; however, it has been replaced by other agents, because it is a major sensitizer. Because of the continuing confusion about the name of this common sunscreen agent, the FM requires that product labels list it as "aminobenzoic acid"; in addition, each time this name appears on product labeling, it must be followed by "(PABA)" so patients know which chemical entity they are using. One advantage of this agent is its ability to penetrate into the horny layer of the skin and provide lasting protection. Its substantivity on sweating skin is significant but is reduced on skin that is immersed in water. The only recommended derivative of aminobenzoic acid is padimate O. The disadvantages of alcoholic solutions of aminobenzoic acid include contact dermatitis, photosensitivity, stinging and drying of the skin, and yellow staining of clothes on exposure to the sun. Products containing padimate O will not cause staining of the clothing, which may offer an advantage over aminobenzoic acid-containing products. Because of the possibility of allergic reactions to aminobenzoic acid and its derivatives and their broad spectrum of action, many sunscreen products now contain benzophenones in their formulations

Patient Factors

An SPF product of 30+ should be used by people who burn easily and tan minimally at bes Water-resistant products are usually effective for at least 40 or 80 minutes when used during the above activities

Selected Meds associated with photosensitivity reactions (by category)

Anticancer Drugs: Dacarbazine Daunorubicin Fluorouracil Methotrexate Vinblastine Anticonvulsants: Carbamazepine Gabapentin Lamotrigine Phenytoin ' Antidepressants: Bupropion Selective serotonin reuptake inhibitors Trazodone Venlafaxine Antihistamines: Cetirizine Diphenhydramine Antihypertensives: Angiotensin-converting enzyme inhibitors Calcium channel blockers Hydralazine Labetalol Methyldopa Minoxidil Sotalol Anti-Infectives: Azithromycin Ceftazidime Dapsone Gentamicin Griseofulvin Itraconazole Ketoconazole Metronidazole Pyrazinamide Quinolones Ritonavir Saquinavir Sulfonamides Tetracyclines Trimethoprim Trovafloxacin Zalcitabine Antimalarials: Chloroquine Quinine Antipsychotics/Phenothiazines: Haloperidol Olanzapine Ziprasidone Coal Tar and Derivatives: DHS Tar Gel Shampoo Ionil T Plus Shampoo Neutrogena T/Derm Body Oil Neutrogena T/Gel Extra Strength Diuretics: Acetazolamide Amiloride Furosemide Metolazone Triamterene Thiazide diuretics Nonsteroidal Anti-Inflammatory :Drugs Celecoxib Ibuprofen Indomethacin Methoxsalen Naproxen Psoralen Trioxsalen Sunscreens: Aminobenzoic acid Aminobenzoic acid derivatives Benzophenones Cinnamates Homosalate Menthyl anthranilate Oxybenzone Miscellaneous: Amiodarone (antiarrhythmic) Benzoyl peroxide Gold salts (antiarthritic) Isotretinoin (antiacne) Quinidine sulfate (antiarrhythmic) Retinoids Statins

Dibenzoylmethane Derivatives

Avobenzone is the first of a new class of sunscreen agents effective throughout the entire UVA range offers the best protection in the UVA range compared with the other chemical sunscreens on the market Avobenzone is easily degraded by exposure to sunlight; it is found in newer sunscreen products combined with octocrylene, salicylates, methylbenzylidene camphor, and micronized zinc oxide and/or titanium dioxide to enhance stability of the product and to extend the product's spectrum of coverage through the UVA and UVB spectrum

Clinical Presentation Skin Cancer

BCC is a translucent nodule with a smooth surface. It is usually firm to the touch and may be ulcerated or crusted. It is generally found as an isolated lesion on the nose or other parts of the face, although multiple lesions are sometimes found. SCC, on the other hand, is a slow-growing, isolated papule or plaque on sun-exposed areas of the body. Self-examination for melanoma uses four factors (A-B-C-D) for evaluation: Asymmetric shape; Border irregularity or poorly defined border; Color variation within the same mole or a change in color; and Diameter larger than 6 mm. A mole with these characteristics and any new growth or change in appearance of the skin (including the lips) should be evaluated by a dermatologist

Antibiotic Products

Betadine First Aid Antibiotics + Moisturizer Ointment -Polymyxin B sulfate 10,000 U/g; bacitracin zinc 500 U/g Q-tips Treat & Go -Cotton swabs containing bacitracin 500 U/g Gold Bond First Aid Antibiotic Ointment -Bacitracin zinc 500 U/g; polymyxin B sulfate 10,000 U/g; neomycin base 3.5 mg/g; pramoxine HCL 10 mg Neosporin Ointment -Polymyxin B sulfate 5000 U/g; bacitracin zinc 400 U/g; neomycin base 3.5 mg/g Neosporin Plus Pain Relief Ointment -Bacitracin zinc 500 U/g; polymyxin B sulfate 10,000 U/g; neomycin base 3.5 mg/g; pramoxine HCL 10 mg Neosporin Plus Pain Relief Cream -Polymyxin B sulfate 10,000 U/g; neomycin base 3.5 mg/g; pramoxine HCl 10 mg Polysporin Ointment/Powder -Polymyxin B sulfate 10,000 U/g; bacitracin zinc 500 U/g

Chemical sunscreen

Chemical sunscreens work by absorbing and thus blocking the transmission of UVR to the epidermis. An active ingredient absorbs at least 85% of the radiation in the UV range at wavelengths from 290 to 320 nm, but the agent may or may not allow transmission of radiation to the skin at wavelengths longer than 320 nm.

Clouds and UV

Contrary to popular opinion, cloud cover filters very little UVR; 70%-90% of UVR will penetrate clouds, depending on the clouds' density However, clouds tend to filter out the infrared radiation that contributes to the sensation of heat, creating a false sense of security against a burn

Photoallergy

Drug photoallergy (a relatively uncommon immunologic response) involves an increased, chemically induced reactivity of the skin to UVR and/or visible light. UVR (primarily UVA) triggers an antigenic reaction in the skin. This reaction, which is not dose related, usually is seen after at least one prior exposure to the involved chemical agent or drug.

Clinical Presentation Drug Photosensitivity

Drug photoallergy presents similar to allergic contact dermatitis (e.g., poison ivy) and is characterized by pruritus with erythematous papules, vesicles, bullae, and/or urticaria (see Color Plates, photograph 25). Phototoxicity is most likely to appear as exaggerated sunburn with pruritis,1 but urticaria may also occur (see Color Plates, photograph 26).

Clinical Presentation Photodermatoses

Each photodermatosis has a unique morphology. Polymorphous light eruption alone can have multiple morphologic presentations of pruritus with papules, vesicles, plaques, and/or urticaria.

Other Chemical Sunscreens

Ensulizole does not fit into any of the above classes. It is a pure UVB sunscreen with an absorbance range of 290-320 nm. Ecamsule (terephthalylidene dicamphor sulfonic acid) is a new molecule that FDA approved in 2006. It is a water-resistant broad-spectrum sunscreen. Ecamsule is often combined with octocrylene to increase its stability to light

Influence UV Index

Factors that influence the UV index are time of day (UVR exposure is greater at midday than in the early morning or late afternoon); ozone (limited amounts of ozone increase the amount of UVR exposure); altitude (higher altitudes receive greater UVR exposure); season (spring and summer have greater UVR exposure); surface (reflective surfaces increase UVR exposure); latitude (UVR exposure increases closer to the equator); and land cover (less tree cover increases UVR exposure)

20 disorders of photodermatoses

Idiopathic Disorders: Actinic prurigo Chronic actinic dermatitis Hydroa vacciniforme Polymorphous light eruption Solar urticaria Photoaggravated Dermatoses: Atopic dermatitis Chronic actinic dermatitis Cutaneous T-cell lymphoma Dermatomyositis Disseminated superficial actinic porokeratosis Drug-induced photosensitivity Erythema multiforme Herpes simplex labialis Lichen planus actinicus Pellagra Pemphigus Porphyrias Psoriasis Reticular erythematous mucinosis Rosacea Systemic lupus erythematosus Transient acantholytic dermatosis

Phototoxicity

Like photoallergy, phototoxicity is an increased, chemically induced reactivity of the skin to UVR and/or visible light. However, phototoxicity is not immunologic. It is often seen on first exposure to a chemical agent or drug, is dose related, and usually exhibits no drug cross-sensitivity. Some drugs associated with phototoxicity are listed in Table 38-3. This type of reaction is not limited to drugs but is also associated with plants, cosmetics, and soaps

Fragrance-free, hypoallergenic

Many patients are sensitive to various ingredients (e.g., fragrances, emulsifiers, and preservatives). These patients should try to choose fragrance-free formulations or those that are hypoallergenic

noncomedogenic

Noncomedogenic products do not plug the pores and, therefore, do not exacerbate acne. This property is especially important for teenagers, who usually spend more time outdoors than other age groups and generally would prefer not to use comedogenic sunscreens

Broad Spectrum Labeled

Only broad-spectrum sunscreens with an SPF value of 15 or higher will be able to claim to reduce the risk of skin cancer and early skin aging if they are used as directed along with other skin protection measures. Broad-spectrum sunscreens with an SPF value between 2 and 14 and products that protect against only UVB (not broad spectrum) can claim only to help prevent sunburn

Physical Sunscreens

Physical sunscreens (zinc oxide and titanium dioxide) are considered broad-spectrum UV protectants They are used most often on small and prominently exposed areas by patients who cannot limit or control their exposure to the sun Because titanium dioxide increases the effective SPF of a product and extends the spectrum of protection well into the UVA range, the number of commercial products containing this agent has increased. The FM allows zinc oxide to be used alone or in combination with any of the other sunscreen agents except avobenzone; the exception results from a lack of data on effectiveness

Physical sunscreen

Physical sunscreens are generally opaque and act by reflecting and scattering UVR, rather than by absorbing it. An opaque sunscreen active ingredient reflects or scatters all light in the UV and visible ranges at wavelengths from 290 to 777 nm. The sunscreen thereby minimizes suntan and sunburn.

No Broad Spectrum Label

Products that are not broad spectrum must carry a label warning: "Skin Cancer/Skin Aging Alert: Spending time in the sun increases your risk of skin cancer and early skin aging. This product has been shown only to help prevent sunburn, not skin cancer or early skin aging."

Topical Anesthetics

Relief is short lived, lasting only 15-45 minutes Lower concentrations are preferred when the skin surface is not intact because drug absorption is enhanced no more than 1%-2% of BSA to avoid systemic toxicity applied no more than 3 or 4 times daily continuous pain relief cannot be obtained with these agents Amine and Caine-Type Local Anesthetics: Benzocaine 5-20 Butamben picrate 1 Dibucaine 0.25-1 Dibucaine hydrochloride 0.25-1 Dimethisoquin hydrochloride 0.3-0.5 Dyclonine hydrochloride 0.5-1 Lidocaine 0.5-4 Lidocaine hydrochloride 0.5-4 Pramoxine hydrochloride 0.5-1 Tetracaine 1-2 Tetracaine hydrochloride 1-2 Antihistamines: Diphenhydramine hydrochloride 1-2 Tripelennamine hydrochloride 0.5-2

Stage II

Severe sunburn include blistering or partial-thickness skin loss that involves all the epidermis and part of the dermis. Because the injury involves a break in the skin, drainage from the wound area may occur, in addition to pain, edema, and erythema will desquamate or "peel" over a period of several days slight chance of bacterial infection because of the loss of the outer skin barrier Pain, edema, and skin tenderness accompany erythema. Systemic symptoms such as vomiting, low-grade fever, chills, weakness, and shock may be seen in patients in whom a large portion of the skin surface has been affected After exfoliation and for several weeks thereafter, the skin will be more susceptible than normal to sunburn

Dry Skin

Some patients have normally dry skin; sunbathing can further exacerbate this problem. These patients should avoid ethyl and isopropyl alcohols, which are included in a number of commercial sunscreen products and can further dry the skin

Intended Use

Some patients may want to use sunscreens to prevent sunburn or the photoaging effects of UVR or to protect themselves from skin cancer. Others may need protection from sun exposure because they are taking photosensitive drugs or they suffer from a photodermatosis Generally, if a product is to be used to prevent skin cancer, reduce the chances of a photosensitivity reaction, or reduce the risk of triggering a skin disorder induced or aggravated by UVR, a broad-spectrum SPF value of 15 or higher is recommended

Clinical Presentation Sunburn

Sunburn is, in fact, a burn. It most often is seen as a superficial burn with a reaction that ranges from mild erythema to tenderness, pain, and edema (see Color Plates, photograph 24). Severe reactions to excessive UVR exposure can sometimes produce burns that range in severity from superficial partial-thickness to full-thickness with the development of vesicles (blisters) or bullae (many large blisters), as well as fever, chills, weakness, and shock. Shock caused by heat prostration or hyperpyrexia can lead to death

Tanning Beds

Tanning bed use has been associated with increased risk of skin cancers. Health care providers should advise parents and patients about the long-term hazards related to tanning devices; in addition, providers should explain that tanning devices currently provide no accepted health benefits

Applying

The FDA standard for application of sunscreens is 2 mg/cm2 of body surface area. This standard means that, for sufficient protection, the average adult in a bathing suit should apply nine portions of sunscreen of approximately one-half teaspoon each, or approximately 4 and one-half teaspoons (22.5 mL) total. The sunscreen should be distributed as follows: •Face and neck: one-half teaspoon. •Arms and shoulders: one-half teaspoon to each side of body. •Torso: one-half teaspoon each to front and back. •Legs and tops of feet: 1 teaspoon to each side of body.

Anthranilates

The anthranilates are ortho-aminobenzoic acid derivatives. Meradimate, the menthyl ester of anthranilic acid, is a weak UV sunscreen with maximal absorbance in the UVA range. It is usually found in combination with other sunscreen agents to provide broader UV coverage.

Water Resistance

The final rule prohibits "waterproof," "sweatproof," and "sunblock" claims, because these terms overstate product effectiveness. Further, water-resistance claims on the front label must indicate whether the sunscreen remains effective for either 40 or 80 minutes while swimming or sweating. These times are based on the standard testing procedure. Products that are not water resistant must instruct consumers to wear a water-resistant product while swimming or sweating

Application labeling

The final rule requires that the sunscreen label recommend the following with regard to sunscreen application: Regardless of the water resistance of the product, it should be applied 15 minutes before sun exposure. Non-water-resistant products should be reapplied at least every 2 hours. Water-resistant products should be reapplied every 2 hours, after 40 or 80 minutes of swimming or sweating (as designated on the label), and immediately after towel drying

SPF Prolongs Exposure Before Burn

The higher the SPF, the more effective the agent is in preventing sunburn. If 60 minutes of sun exposure normally is required for someone to experience two MEDs (a bright erythematous sunburn), a sunscreen with an SPF of 6 will allow that person to stay in the sun 6 times longer (or 6 hours) before receiving the same degree of sunburn (assuming the sunscreen is reapplied at the recommended intervals)

SPF Calculation

The important measure for sunscreens is the SPF, which is derived by dividing the MED on protected skin by the MED on unprotected skin. For example, if a person requires 25 mJ/cm2 of UVB radiation to experience 1 MED on unprotected skin and requires 250 mJ/cm2 of radiation to produce 1 MED after applying a given sunscreen, the product would be given an SPF rating of 10.

Skin Cancer

The majority of NMSCs occur on the most exposed areas of the body (the face, head, neck, and backs of the hands two most common types of NMSC are basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). BCC is often an aggressive, invasive disorder of the epidermis and dermis that can cause serious damage to the skin and underlying tissue. However, it rarely metastasizes. SCC is found in epithelial keratinocytes and grows very slowly

Concerns with use

The two major causes of poor sun protection with sunscreen use are application of inadequate amounts and infrequent reapplication lips often neglected

Combinations

Therefore, the FM requires that each active ingredient contribute a minimum SPF of not less than 2 the finished product must have a minimum SPF of not less than the number of sunscreen active ingredients used in the combination multiplied by 2

Clinical Presentation Premature Aging

This condition is characterized by wrinkling and yellowing of the skin. Conclusive evidence reveals that prolonged exposure to UVR results in elastosis (degeneration of the skin due to a breakdown of the skin's elastic fibers). Pronounced drying, thickening, and wrinkling of the skin also may result. Other physical changes include cracking, telangiectasia (spider vessels), solar keratoses (growths), and ecchymoses (subcutaneous hemorrhagic lesions).2,5,14 (See Chapter 39 for measures for reversing photoaging.)

UVA produces tan

UVA produces a tan by inducing an immediate pigment darkening, resulting from photooxidation of existing melanin and redistribution of melanocytes. The pigment darkening begins to be visible rapidly after exposure and may last for 2 hours after UVR exposure. UVB acts by stimulating melanocyte activity and increasing the number of melanocytes in the skin. This delayed tanning of the skin becomes visible 3-4 days after exposure to UVR and will last from 10 to 30 days depending on skin type and amount of UVR exposure

Vehicles

UVB does not penetrate window glass, UVA does. Most automobile windshields are made from laminated glass that filters most of the UVA. However, side windows are not made from laminated glass; therefore, a significant amount of UVA may pass through to persons in the vehicle. Therefore, patients sensitive to UVA (e.g., those with photodermatoses or those taking photosensitizing drugs) should use appropriate sunscreens even when driving with the windows closed

Water and UVR

Water reflects no more than 5% of UVR, allowing the remaining 95% to penetrate and burn the swimmer. Wet clothes allow transmission of approximately 50% of UVR

Reflected UVR

White or light-colored surfaces (e.g., snow or sand) reflect the UVR that strikes them

systemic analgesics

preferably one with anti-inflammatory activity, such as the NSAIDs. especially in the first 24 hours after overexposure to UVR. cannot tolerate NSAIDs, acetaminophen can provide pain relief, although it is a weak prostaglandin inhibitor and is not an anti-inflammatory agent.

Skin protectant

protect the area from mechanical irritation caused by friction and rubbing, and they prevent drying of the stratum corneum. Products that prevent dryness and provide lubrication should be selected. Generally, the patient may apply a skin protectant as often as needed. If the skin injury has not improved in 7 days or if it worsens during or after treatment, the patient should seek medical attention promptly. Allantoin 0.5-2 Cocoa butter 50-100 Petrolatum 30-100 Shark liver oil 3 White petrolatum 30-100

Skin and SPF

the patient's natural skin type will be the primary factor in determining the sun protection factor (SPF) of the sunscreen product to be used. The lighter the natural skin color (and the more quickly a burn develops), the higher the SPF required for the sunscreen product to prevent sunburn. Avoidance of Sun Exposure

Types of Sunscreens

two major subgroups: chemical sunscreens and physical sunscreen

Product Selection

two primary factors the intended use of the product and specific patient characteristics