1. 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.
Malignant melanoma is the tenth most common cause of cancer death in US
Non-melanoma (ie squamous + basal) is THE most common human malignancy

2. ULTRAVIOLET RADIATION SPECTRUM
UVA (Longwave Radiation)
Range 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

3. ULTRAVIOLET RADIATION SPECTRUM
UVB (Middlewave Radiation)
Range nm
Erythrogenic activity is the highest
Produces new pigment formation, sunburn, Vit D synthesis
Responsible for inducing skin cancer

5. ULTRAVIOLET RADIATION SPECTRUM
UVC (Shortwave or Germicidal Radiation)
Range nm.
Does not reach the surface of the earth.
Is emitted from artificial ultraviolet sources.

6. ULTRAVIOLET RADIATION SPECTRUM
Long-term hazards of skin damage from radiation:
Malignancy:
Squamous cell epithelioma
Actinic keratosis
Basal cell carcinoma
Premature aging
nevus, seborrheic keratosis, solar lentigo
wrinkles, lines, etc

7. SUNSCREEN CLASSIFICATIONS
Physical
Opaque formulations containing:
titanium dioxide
talc, kaolin
zinc oxide
ferric chloride
icthyol, red petrolatum
Mechanism: scatters or reflects UV radiation due to large particle size

8. SUNSCREEN CLASSIFICATIONS
Chemical
Formulations containing one or more:
PABA, PABA esters
benzophenones
cinnamates
salicylates
digalloyl trioleate
anthranilates
Mechanism: absorbs UV radiation

9. SUNSCREENS Sun Protection Factor (SPF) = MED of Photoprotected Skin
MED of Unprotected Skin
MED is minimum dose of radiation which produces erythema
SPFs are determined indoors using xenon lamps which approximate the spectral quality of UV radiation
SPF is an artificially derived measure of skin protection. One time exposure may not reflect importance of cumulative sub-erythemal doses

10. 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.
Environment: snow/white surfaces reflect 70-90%, and when directly overhead water reflects nearly 100% of UVR.
Vehicle: determines skin penetration of sunscreen.

11. SUNSCREENS

12. SUNCREEN AGENTS PABA (Para-aminobenzoic acid)
Very effective in the UVB range ( 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.
Problems with PABA:
1. Contact dermatitis
2. Stains clothing
3. Poor substantivity - poor binding to stratum corneum requiring long contact time

13. SUNCREEN AGENTS PABA Esters (Padimate A, Padimate O, Glyceryl PABA)
Also very effective in UVB range ( )
Most effective in conc % in 65% alcohol
May penetrate less effectively than PABA
Similar application and adverse effect
Less staining

14. SUNCREEN AGENTS
Benzophenones (oxybenzone, dioxybenzone, sulisobensone)
Slightly less effective than PABA.
Absorbs from nm spectrum (ie, UVA & UVB).
Combined with PABA or PABA ester improves penetration and is superior to either agent used alone ( nm wavelength coverage).
Beneficial in preventing photosensitivity rxns.
Contact dermatitis is rare.

15. SUNCREEN AGENTS Cinnamates and Salicylates
Minimally effective, absorb UVB spectrum.
Generally used in combination with one of the above.

16. SUNCREEN AGENTS Anthranilates
Minimally effective, absorbs UVA spectrum nm.
Usually combined with UVB agent to broaden spectrum.

17. 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).

18. TANNING Tan Accelerators Sunless Tanners Tanning Booths
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
Newer types use light source composed of 95% UVA, < 5% UVB (even 1% may increase incidence of skin cancer).

19. PHOTOSENSITIVITY REACTIONS
Photoallergic Reactions
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.

20. PHOTOSENSITIVITY REACTIONS
Phototoxic Reactions
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.

21. 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.
FDA suggests that there is little benefit from SPF formulations > 30.
New research suggests that higher SPF may protect cumulative sub-erythemal doses that may prevent UV damage better. Skin becomes sensitized after initial exposure, and thus takes less UV radiation to cause damage and sunburn.

22. SUNSCREEN PRODUCTS PABA/Ester Oxybenzone Other
Coppertone yes cinnamate
PreSun yes yes
Bull Frog yes cinnamate
Q.T. Quick Tanning cinnamate
Formula 405 Solar Lotion cinnamate

23. OTC BURN THERAPY Burn Depth First degree erythema, no blistering
Second degree erythema and blisters
Third degree No blisters, leathery white, mottled
Fourth degree “Charred”

24. CLASSIFICATION OF BURNS (American Burn Association)
Minor Burns:
Second degree burn
Third degree burn
excludes electrical or inhalation injuries and all poor risk patients.
< 15% BSA
(10% in children)
< 2% BSA not involving eyes, ears, face, hands, feet, or perineum).

25. Estimation of Burned Area
Rule of nines Body Area
Head 9%
Arm 9%
Leg 18%
Anterior Trunk 18%
Posterior Trunk 18%
Perineum 1%

26. 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 fine-mesh gauze
Absorbent intermediate layer to draw and store exudate
Supportive outer layer of rolled gauze bandage

27. Formulation Homomenthyl salicylate 080 Mineral oil 500
Isopropyl myristate

28. Formulation (cream) Suncreen agent 50 Emulsifyer 75 Cetyl alcohol 10
Isopropyl myristate
Liquid paraffin
Glycerol
Water to