Sunscreen

Most dermatologists recommend SPF of?

15 or greater to all patients regardless of skin type.

Theoretically, SPF 15 allows

15 x longer sun exposure without burning

UVA

95% of solar radiation; Penetrates skin deeper than UVB; Causes indirect damage to DNA; Free radical formation; Damage to cellular membranes

Sunscreen types Divided into

chemical absorbers and physical blockers.

Only one truly effective UVA absorber in the U.S. is

avobenzone

SPF decreases with?

exposure to UV

Chemical sunscreens typically aromatic compounds that Absorb

high intensity UV rays, producing excitation to a higher energy state. Return to the ground state results in conversion of absorbed energy to longer, lower energy wavelengths

Sunscreen MOA

ingredients absorb UV energy; Usually the energy is radiated back to the environment as heat or Some dissipate energy by breaking down chemically

SPF is the time period you can

stay in the sun without burning based on your skin complexion.

SPF =

sun protection factor

in the U.S. UVA protection is limited

"UVA/UVB protection," "Broad-Spectrum"; Based on the presence of certain weak UVA absorbers

UVB

1000 x more effective at producing sunburn than UVA; Causes direct damage to DNA

Oxybenzone

Considered a broad-spectrum UVR absorber; Significantly augments UVB when used in combination

Titanium Dioxide

Ideal sunscreen; Chemically inert; Safe; Blocks full UV spectrum

Sunscreen monograph

Ingredients, formula testing, finished product labeling regulated

"Water-resistant" sunscreen

Maintains the SPF level after 40 minutes of water immersion.

"Very water-resistant" , formerly "water-proof" sunscreen

Maintains the SPF level after 80 minutes of water immersion

Sunscreens Regulated by FDA as

OTC drugs

Avobenzone

Often referred to by its trade name, Parsol 1789; Probably the best UVA absorber; Used with UVB absorbers for broad-spectrum coverage

"Broad or Full-Spectrum" Sunscreen

Protects against UVB and UVA

Physical Blocker Sunscreen

Reflect or scatter UVR

Sunscreen Prevents the following

Sunburn, Skin or lip damage, freckling, skin discoloration, Skin aging, Skin cancer, Phototoxic or photoallergic drug reactions, Photosensitivity diseases

Examples of Sunscreen Physical blockers

Titanium dioxide; Zinc oxide

UVA further broken down:

UVAI- 340-400 nm; UVAII- 320-340 nm

Zinc Oxide

Works as well as titanium dioxide

Sunscreen effectiveness

reduce AK's and solar elastosis; Help reduce drug photosensitization and photo-induced or aggravated dermatoses