Benzophenones are also found in shampoos, soaps, hair sprays and dyes, paints,
varnishes, and lacquers. The maximal absorption for each is about 290 nm, but both
are limited because of poor substantivity and sensitization.
with oxybenzone and contact dermatitis with dioxybenzone occur commonly, with the
latter usually occurring as a contact urticaria.
71 Systemic absorption has also been
noted with oxybenzone, and it can be detected in the urine and bloodstream.
Anthranilates, such as meradimate (menthyl anthranilate), are weak UVB-absorbing
sunscreens with an absorption spectrum extending into the UVA range. As with the
salicylates, they have low molar absorptivity, with a maximal absorption of
46 Meradimate has a low risk of sensitization and a desirable
absorption spectrum, especially when it is used in combination with other sunscreens
to give broad-spectrum protection.
As a prototype of the dibenzoylmethane class, avobenzone (butyl
methoxydibenzoylmethane) has high molar absorptivity and absorption spectra
exclusively in the UVA range, with maximal absorption at approximately 360 nm.
is commonly formulated with UVB sunscreens to broaden UVR coverage.
Avobenzone loses approximately 35% of its absorption capacity about 15 minutes
after UVR exposure, because of the photoinstability of the compound, thereby
reducing its UVA protection efficacy.
74 One molecule of avobenzone can absorb
UVA radiation only once, making it inactive from that time forward as opposed to
zinc oxide or titanium dioxide, which can reflect UVA radiation over and over again
with minimal decay. All of the avobenzone applied to the skin is virtually rendered
inactive after 5 hours of UVA exposure. Avobenzone is also not compatible with
octinoxate, the most powerful UVB filter.
75 Photostability of avobenzone can be
increased with the use of UV absorbers, as well as non-UV filters. Neutrogena has
marketed this technology under the name of Helioplex, which initially stabilized
avobenzone using oxybenzone and diethylhexyl 2,6-naphthalate (DEHN), but has now
broadened to include additional technologies and ingredients.
Ecamsule is a camphor derivative that protects against short UVA rays and is
photostable and water resistant, and has low systemic absorption.
only approved ecamsule for use in certain formulations such as the combination of
2% ecamsule/2% avobenzone/10% octocrylene cream (Anthelios SX, L’Oreal
USA). This OTC product is only available in the United States as a moisturizing
cream with an SPF rating of 15, with the FDA determining that more research was
needed to evaluate the safety and efficacy of ecamsule in other concentrations.
combination provides continuous protection across most of the UV spectrum (290–
400 nm range), with ecamsule providing protection within the short UVA range
(320–340 nm), filling the gap between octocrylene and avobenzone capabilities
(210–290 nm, and 340–400 nm, respectively). The photostability of the ecamsule and
octocrylene–avobenzone combination provides residual protection at 1 and 5 hours
(1 hour, 100% UVB protection and 97% UVA protection; 5 hours, 90% UVB
protection and 80% UVA protection). Adverse events associated with its use are
infrequent and include acne, dermatitis, xerosis, eczema, erythema, pruritus, skin
There are two additional formulations of ecamsule. Mexoryl SX is a water-soluble
form suitable for daytime sunscreens, including sunscreen-containing moisturizers
Inorganic sunscreens are opaque formulations made of particulate insoluble
compounds, incorporated into a vehicle, which scatter and absorb UV rays. Both size
of the particles and thickness of the film determine the degree of protection.
Currently, there are only two inorganic sunscreens approved by the FDA: titanium
77,78 Other inorganic sunscreens include magnesium oxide, red
veterinarian petrolatum, iron oxides, kaolin, ichthammol, and talc. Iron oxides and
talc continue to be found in commercially available sunscreen products and
cosmetics, whereas kaolin and ichthammol may be found in products such as
cleansers, moisturizers, and ointments. These compounds are often used in
conjunction with chemical sunscreens to formulate products of higher SPF and as
single-ingredient products. When used alone, they are usually placed in an ointment
base designed specifically for vulnerable parts of the body, such as the nose, cheeks,
Inorganic sunscreens are important in individuals who are
unusually sensitive to UVA and visible light, such as those with vitiligo, a skin
condition with amelanotic lesions (white patches) surrounded by areas of normally
pigmented skin. Appropriately colored formulations can be used to camouflage and
protect these vulnerable amelanotic lesions.
Inorganic sunscreen agents are
preferred for persons who need absolute UVR and visible light protection (e.g.,
young children, persons with skin types I through IV who receive constant exposure,
and persons with drug photosensitivity reactions, xeroderma pigmentosa, lupus
erythematosus, and other photosensitive skin reactions).
Despite some advantages, inorganic sunscreens are not widely accepted because
they are visible to others, messy, and occlusive when applied to the skin. They have a
higher substantivity, but may melt in the heat of the sun, limiting their protection to a
few hours. Physical sunscreen products tend to be so occlusive that they may cause or
worsen acne or obstruct sweat glands.
33 Substantial effort has been made to improve
the shortcomings of these products by reducing the particle size to improve the
cosmetic appearance. This has created a growing trend toward incorporating
nanoparticles of titanium dioxide and zinc oxide, which have been shown to have
superior UV protection while maintaining cosmetic elegance. Concern about toxicity
of these agents has been raised because of the potential for increased skin penetration
and interaction with lower portions of the epidermis; however, this has been
disproved in both in vivo and in vitro studies.
79–83 No current regulation in the United
States exists regarding the testing and labeling of nanosized titanium or zinc oxides.
The addition of botanical antioxidants and vitamins C and E to a broad-spectrum
sunscreen may further decrease UV-induced damage compared with sunscreen alone
due to neutralization of free radicals.
78,84 Antioxidants have received increased
attention for use as photoprotective agents, particularly because of the observation
that vitamin C levels in the skin can be severely depleted after UVR exposure.
Vitamins C and E, either taken orally or applied topically (incorporated into a
commercially available sunscreen product), may provide additive protection against
both UVA- and UVB-induced photodamage.
85,86 Topically applied antioxidants do not
have adequate diffusion into the epidermal layer, however, and are susceptible to
If recommended, they should only be used in conjunction with
adequate sunscreen. Commercially available products can be found with
combinations of antioxidants and broad-spectrum sunscreens, specifically those
Given their plans for the week of vacation and amount of UV exposure likely, R.J.
and J.J. should consider a broad-spectrum product with high substantivity and a high
degree of water resistance to offer the best protection.
CASE 42-1, QUESTION 4: According to your assessment of R.J. and J.J., you determine that they have
What considerations are important in recommending sunscreens for R.J. and J.J.?
The first consideration for recommending an appropriate sunscreen to R.J. and J.J.
is their skin type. R.J. has skin type IV, suggesting that a sunscreen with an SPF of at
least 15 would provide adequate protection for her (Table 42-3). J.J. has skin type II,
suggesting that a sunscreen with an SPF of 30 to 50 would be required to provide
adequate protection for him. Furthermore, the history of contact dermatitis and
photosensitivity reaction exhibited by R.J. and J.J., respectively, is important when
recommending use of a sunscreen.
87 The contact dermatitis that R.J. experienced from
hair dyes and shampoos may have been caused by paraphenylenediamine, an
88 or a benzophenone, which sometimes is included in
products such as hair dyes and shampoos.
Because cross-reactivity between paraphenylenediamine and PABA or its
derivatives is possible, a sunscreen for R.J. that does not contain PABA or a
benzophenone should be recommended. Cinnamates and anthralates rarely cause
contact dermatoses, which would be ideal for R.J.
Because both contain sulfa moieties, the photosensitivity reaction that J.J.
experienced while taking TMP-SMX may indicate that he might be susceptible to a
cross-sensitivity reaction with PABA or its derivatives. This reaction to TMP-SMX
also indicates that J.J. may be susceptible to a photosensitivity reaction with HCTZ.
If a photosensitivity reaction is likely, it is advisable to recommend an SPF of 30 or
necessary to provide J.J. with adequate protection. Broad-spectrum chemical
sunscreens commonly contain a benzophenone and a cinnamate. A broad-spectrum
ester derivatives to cause photocontact dermatitis,
63 a broad-spectrum combination
product that contains Padimate O could be recommended for J.J. If the
photosensitivity reaction is caused by visible light, it would also be necessary to
recommend an inorganic physical sunscreen to block all sunlight or complete
50 With all of these issues considered, it may be preferable to
recommend an alternative antihypertensive medication for J.J. that would not place
him at risk for a photosensitivity reaction.
CASE 42-1, QUESTION 5: What photoprotective measures should be provided for P.J. and L.J.?
Sun protection during childhood is very important, considering that most of a
person’s lifetime of sun exposure occurs in childhood and that the harmful effects of
38 However, infants and toddlers are at increased risk of over
sunscreen products because of an increased body-surface-area to body-weight
ratio compared to adults and a lower ability to metabolize absorbed drug.
therefore recommended that sunscreen should not be used for children younger than 6
91 P.J. needs to be kept out of direct sunlight and, when outside, must
be protected with proper clothing and shading.
L.J. should be protected with a PABA-free, inorganic UV filter sunscreen such as
zinc oxide with an SPF of at least 15. Inorganic UV filters are preferred for children
between 6 months and 2 years due to lack of systemic absorption.
a sunscreen with an SPF of at least 15 for the first 18 years of life can reduce the
lifetime incidence of nonmelanoma skin cancers by about three-fourths.
the sun during 6 hours of maximal exposure (i.e., 10 AM–4 PM), or otherwise for an
extended period, he should wear protective clothing, covering as much of his body as
94 Tightly woven clothing, long sleeves, and pants protect the skin from
almost all UVR, whereas loosely woven clothing or wet T-shirts can allow up to
30% of UVR to pass through to the skin. Although not complete, water is thought to
The transmission of UVR through a fabric is measured using a spectrophotometer
or spectroradiometer. The ultraviolet protection factor (UPF), rather than SPF, has
been recommended as a measure of the sun-protective properties of fabrics.
calculated using a formula based on UV transmission through the fabric and the
erythema responsible for human skin. For example, if a fabric has a UPF of 20, then
only one-twentieth of the UVR at the surface of the fabric actually passes through it.
Certain synthetic fabrics have UPF values that exceed 500, making them vastly
94 Table 42-4 compares the UPF with the amount of effective
No woven fabric provides complete coverage because the holes between the
threads permit UVR transmission. A baseball cap shields little more than the upper
central forehead. Broad-brimmed hats can protect the ears, neck, nose, and cheeks,
but may provide inadequate protection against SCC of the head or neck.
an ultraviolet-absorbing ingredient for fabric softeners (e.g., bisoctrizole, Tinosorb
M, BASF) is promoted to reduce transmission of excessive UVA and UVB radiation
through fabrics to the skin, through absorption of UV radiation without impairing
whiteness. This chemical absorption process has a high affinity for cotton fibers at
various washing temperatures. Available as a laundry additive (e.g., Sun Guard,
Phoenix Brands), it works by binding to laundered fibers, and through accumulation,
it increases the UV protection up to UPF 30 through up to 20 wash and rinse
Two types of sunscreens are appropriate for use in children. A lotion is preferred for
total body application versus an alcoholic lotion or gel because alcoholic
preparations can cause stinging, burning, and irritation of the skin and eyes. Physical
sunscreens (e.g., zinc oxide) are available in bright colors and are recommended for
selected body areas, such as the nose, cheeks, and shoulders. PABA and its
derivatives are considered potentially harmful to a child’s tender skin. For
adolescents with acne vulgaris, the use of an oil-free, noncomedogenic sunscreen
formulation (e.g., Neutrogena Clear Face Break-Out Free Liquid-Lotion Sunscreen)
and a lip balm that contains a sunscreen of at least SPF 15 (e.g., Blistex or ChapStick
Sunblock [SPF 30]) would be appropriate.
CASE 42-1, QUESTION 6: What instructions should you provide R.J. and J.J. on how to apply the
sunscreen that you have chosen for each of their family members?
Because R.J. and J.J. are planning to be active on the beach, sunscreens that are
water resistant are recommended. Before complete application of the sunscreen to
the body, because of the risk of cross-sensitivity reactions, patients can perform a
patch test by applying a small quantity of the sunscreen to the inner aspect of the
forearm and covering with a small bandage overnight.
Most persons apply 20% to 60% of the required amount of sunscreen needed to
achieve the SPF of their product.
48,51–54 Because of this, a method has been developed
to determine an approximate volume of sunscreen product needed for adequate
101 This rule states that you should use more than half a teaspoon on each of
your head and neck area and arms, and more than a teaspoonful on each of your
anterior and posterior torso and your legs. This application size was determined
based on the dose used in FDA sunscreen testing (2 mg/m2
application techniques have demonstrated inadequate application at all body
102 The worst protected areas were the ears and top of the feet, and the back
was poorly protected if sunscreen was self-applied. Patients should be reminded to
apply sunscreen on those often forgotten areas, such as the hands, cheeks, neck, ears,
and dorsum of the feet. It is best to reapply the sunscreen every 1 to 2 hours or after
sweating, swimming, or toweling off. There is evidence that early reapplication
within 20 to 30 minutes be able to partly compensate for initial
If J.J. (skin type II) normally burns after 30 minutes of exposure to the sun, a
sunscreen with an SPF of 15 to 30 may provide up to 7.5 hours (0.5 hours × 15 [SPF
15]) of photoprotection from UVB. However, a high SPF product may provide only
partial protection against UVA, with little or no protection from infrared radiation.
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