Transcript SUNSCREENS
SUNSCREENS
Skin damage from radiation is cumulative
whether sunburn occurs or not.
Annual incidence:
500,000 cases of basal cell CA occur.
100,000 cases of squamous cell CA occur.
20,000 cases of malignant melanoma
occur.
ULTRAVIOLET RADIATION
SPECTRUM
UVA (Longwave Radiation)
Range 320-400 nm
Erythrogenic activity is weak, however
penetrates dermis
Responsible for development of slow natural
tan
Most drug-induced photosensitivity rxn
occurs
UVA may augment the effects of UVB
ULTRAVIOLET RADIATION
SPECTRUM
UVB (Middlewave Radiation)
Range 290-320 nm
Erythrogenic activity is the highest
Produces new pigment formation, sunburn,
Vit D synthesis
Responsible for inducing skin cancer
ULTRAVIOLET RADIATION
SPECTRUM
UVC (Shortwave or Germicidal Radiation)
Range 100-290 nm.
Does not reach the surface of the earth.
Is emitted from artificial ultraviolet
sources.
ULTRAVIOLET RADIATION
SPECTRUM
Long-term hazards of skin damage
from radiation:
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Malignancy:
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Squamous cell epithelioma
Actinic keratosis
Basal cell carcinoma
Premature aging
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nevus, seborrheic keratosis, solar lentigo
wrinkles, lines, etc
SUNSCREEN CLASSIFICATIONS
Physical
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Opaque formulations containing:
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titanium dioxide
talc, kaolin
zinc oxide
ferric chloride
icthyol, red petrolatum
Mechanism: scatters or reflects UV
radiation due to large particle size
SUNSCREEN CLASSIFICATIONS
Chemical
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Formulations containing one or more:
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PABA, PABA esters
benzophenones
cinnamates
salicylates
digalloyl trioleate
anthranilates
Mechanism: absorbs UV radiation
SUNSCREENS
Sun Protection Factor (SPF) =
MED of Photoprotected Skin
MED of Unprotected Skin
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MED is minimum dose of radiation which
produces erythema
SPFs are determined indoors using xenon
lamps which approximate the spectral
quality of UV radiation
SUNSCREENS
Factors which influence effectiveness of SPFs
– Difference in skin types.
– Thickness of the applied sunscreen.
– Time of day.
– Altitude: each 1,000 ft increase adds 4% to the intensity of
erythema producing UV radiation; thus intensity is about
20% greater in Pocatello than at sea level.
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Environment: snow/white surfaces reflect 70-90%, and
when directly overhead water reflects nearly 100% of UVR.
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Vehicle: determines skin penetration of sunscreen.
SUNSCREENS
Category Skin Type
SPF
I
Always burns, never tans
15 >
II
Burns easily
15
III
Burns moderately, (avg caucasian)
10-15
IV
Burns minimally, tans well (olive skin”)
6-10
V
Rarely burns, tans profusely (brown skin)
4-6
VI
Never burns (black skin)
none
SUNCREEN AGENTS
PABA (Para-aminobenzoic acid)
Very effective in the UVB range (200-320 nm).
Most effective in conc of 5% in 70% ethanol.
Maximum benefit when applied 60 min prior to
exposure (to ensure penetration and binding to stratum
corneum).
Does NOT prevent drug/chemical-induced
photosensitivity rxn.
Contact dermatitis can develop.
May produce transient drying/stinging from alcohol
content (may be alleviated by adding 10-20% glycerol).
May stain clothing.
SUNCREEN AGENTS
PABA Esters (Padimate A, Padimate O,
Glyceryl PABA)
Also very effective in UVB range (280-320)
Most effective in conc. 2.5-8% in 65% alcohol
May penetrate less effectively than PABA
Similar application and adverse effect
Less staining
SUNCREEN AGENTS
Benzophenones (oxybenzone, dioxybenzone,
sulisobensone)
Slightly less effective than PABA.
Absorbs from 250-400 nm spectrum (ie, UVA & UVB).
Combined with PABA or PABA ester improves
penetration and is superior to either agent used alone
(200-400 nm wavelength coverage).
Beneficial in preventing photosensitivity rxns.
Contact dermatitis is rare.
SUNCREEN AGENTS
Cinnamates and Salicylates
Minimally effective, absorb UVB spectrum.
Generally used in combination with one of the
above.
SUNCREEN AGENTS
Anthranilates
Minimally effective, absorbs UVA spectrum
250-322 nm.
Usually combined with UVB agent to broaden
spectrum.
USE IN YOUNG CHILDREN
Not recommended in children < 6 mos
(due to theoretical concern that percutaneous
absorption may be greater and excretory
functions may not be mature enough to
handle).
No reported cases of toxicity.
Recommend clothing (hats, etc).
TANNING
Tan Accelerators
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Contain tyrosine - necessary for production
of melanin, no evidence to support efficacy
Sunless Tanners
– Dihydroxyacetone darkens outermost layer
– Use at night, sunscreen during day
Tanning Booths
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Newer types use light source composed of
95% UVA, < 5% UVB (even 1% may
increase incidence of skin cancer).
PHOTOSENSITIVITY REACTIONS
Photoallergic Reactions
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Radiation alters drug, becomes antigenic or acts
as hapten.
Requires previous exposure.
Not dose related.
Induced by chemically related agents.
Eruption may present as urticarial, eczematous,
bullous, or sunburn-like reactions.
Usually caused by topical agents.
PHOTOSENSITIVITY REACTIONS
Phototoxic Reactions
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Radiation alters drug to toxic form, causes
tissue damage.
Does not require previous exposure.
Dose related.
No cross-sensitivity.
Within several hours of exposure - appears
as exaggerated sunburn.
CHOOSING SPF RATING
HIGH SPF SUNSCREENS
Can achieve higher SPF by combining
two or more agents.
SPF 30 (3%) vs 15 (6%) of radiation
penetrating skin.
SUNSCREEN PRODUCTS
PABA/Ester Oxybenzone Other
Coppertone
PreSun
yes
Bull Frog
Q.T. Quick Tanning
Formula 405 Solar Lotion
yes
cinnamate
yes
yes
cinnamate
cinnamate
cinnamate
OTC BURN THERAPY
Burn Depth
– First degree
– Second degree
– Third degree
– Fourth degree
erythema, no blistering
erythema and blisters
No blisters, leathery
white, mottled
“Charred”
CLASSIFICATION OF BURNS
(American Burn Association)
Minor Burns:
Second degree burn
< 15% BSA
(10% in children)
Third degree burn
< 2% BSA not involving
eyes, ears, face, hands,
feet, or perineum).
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excludes electrical or
inhalation injuries and all
poor risk patients.
Estimation of Burned Area
Rule of nines
Head
Arm
Leg
Anterior Trunk
Posterior Trunk
Perineum
Body Area
9%
9%
18%
18%
18%
1%
OTC Treatment of Minor
Burns/Sunburns
Ice/cool water
Cleansing - water and nonirritating soap
Dressings (usually only for second degree burns)
– Nonadherent primary layer of sterile finemesh gauze
– Absorbent intermediate layer to draw and
store exudate
– Supportive outer layer of rolled gauze
bandage
Formulation
Homomenthyl salicylate
Mineral oil
Isopropyl myristate
080
500
420
Formulation (cream)
Suncreen agent
Emulsifyer
Cetyl alcohol
Isopropyl myristate
Liquid paraffin
Glycerol
Water to
50
75
10
150
170
30
1000