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Sunscreens Products

VIEWS: 10 PAGES: 7

									                                                       Sunscreens Products
                                                                                                                  Lecture #1 – 8/29/07
Skin Physiology
   - 3 Main Layers
         o Epidermis
                 Stratum corneum – dead cells, constantly slaughed
                 Squamous cell (keratinocyte) layer – live cells
                 Basal layer (also contains melanocytes) – deepest layer
                 Basement membrane
         o Dermis
         o Subcutis (Subcutarnous Layer)
   - Melanocytes
         o Fxn: Synthesize melanin (pigment), found among basal cells in epidermis
         o Activity of melanocytes determines skin color
         o MSH (Melanocyte Stimulating Hormone)
                 Produced by pituitary gland (tied to optic nerve)
                 Stimulates melanocytes to produce melanin
                 Light stimulates pituitary gland  produces MSH  produce melanin
                 Ex/ A person injected with MSH will get darker
                 Wearing sunglasses blocks off light rays  no MSH  no melanin produced  increases susceptibility to sunburn
                 Tyrosinase (enzyme) activates melanin synthesis from Tyrosine in the melanocyte
                        Albinos lack Tyrosinase (no color)
                        Tyrosine  Dopa (via Tyrosinase)  Dopaquinone (via Tyrosinase)  1) Eumelanin (black/brown), 2)
                         Pheomelanin (red/yellow) – color depends on your race
   - Melanin
         o Absorbs free radicals generated from UV radiation & protects host cell from ionizing radiation found in UV light
         o Absorbing UV radiation helps protect cells from damage
         o Therefore, sun tanning is the skin’s natural defense against UV
   - Tanning
         o Repeating UV exposure for short time over several days will build p enough pigment to a protective level
         o Occurs after DNA damage has already occurred
         o
   - UV Radiation
         o Vitamin D synthesis (increase calcium & phosphate absorption)
         o Blood & immune cell development
         o Treatment of certain diseases (rickets, psoriasis, vitiligo)
   - Sunburn
         o Damaged skin cells responding to prolonged UVR
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         o Increased blood flow to damaged area d/t immune system
               WBC remove damaged cells
         o Nerve endings for pain send signals to brain
               Damagned cells released chemicals that activate pain receptors
               Sunburned skin gets very sensitive
         o Effective 4hrs after exposure, peaks 8-24hrs
         o DNA mutates in next generation of cells
         o Repeated sunburnskin cancer risk increases

UVR Effects
  - Short-term:
         o Erythema, tenderness, ever, chills, pain, weakness, edema, shock
         o Thickened epidermis to protect underlying cells
         o UVR alters keratinocytes in epidermis, triggering immune response
  - Long-term:
         o Drying, thinning, wrinking kin
         o Blotchy Pigmentation/Freckles
         o Chronic skin conditions
         o Skin cancer

Cancers
Type                     Origin                    Metastasis                  Process                     Notes
Basal Cell Cancers       - Begins in basal cell    - Can invade bone or        - 3 varieties               - Slow-growing
                         layer of epidermis        other tissues beneath the   - All forms may bleed,      - Can cause disfiguration
                         - Develops on sun-        skin, but rarely            not but a common sign
                         exposed areas             metastasizes                - Lesions may develop a
                                                                               rolled border and crusted
                                                                               center, then become
                                                                               smaller and less visible

Squamous Cell Cancers    - Starts in epidermal     - More likely to            - May start as a scaly      - More aggressive than
                         keratinocytes (squamous   metastasize                 patch  scales harden,      basal cell cancer
                         cells)                                                base red/inflamed          - Invades tissues
                         - Found on sun-exposed                                develop thick crust with    beneath skin
                         areas of body                                         firm border  can
                                                                               expand rapidly,
                                                                               producing a large nodule

                                                                2
                                                                                    may ulcerate and
                                                                                   metastasize

Melanoma skin cancer       - Begins in melanocytes    - More likely to                                  - Less common, but
                           (in epidermis or dermis)   metastasize or spread to                          accounts for nearly all
                           - Found on trunk (males)   other parts of body (Ie.                          skin cancer deaths
                           and lower                  Livery, lung, bone, brain)
                           legs/everywhere
                           (females)

   -   ABCD Rule for Moles
          o A=Asymmetry
          o B=Border irregularity
          o C=Color not uniform
          o D=Diameter (more than 6mm)
   -   Prevention is KEY

Strategies for UVR Protection
   - Tanning - natural sunlight or artificial UV light
          o Tanning beds: new devices give off both UVA/UVB, simulating the sun
                  UVA alone is not effective in promoting a “tan”
          o Tanning accelerators
                  Lotion/pills, contain Tyrosine, stimulate melanin formation
   - Sun Avoidance or Behavioral change
   - Protective clothing
          o Wet or loosely woven clothes transmit 30% UVR
          o Tightly woven material, long sleeves, darker colors give more protection
          o Patented 30+SPF fabric gives UVA/UVB protection
          o UPF (UV Protection Factor); ex/UPF20 = only 1/20th of sun’s UVR can pass through
   - Sunscreen
          o Reflects, absorbs, or disperses UVR to protect skin and reduce damage caused by sun
          o SPF = measures ability to screen or block UVB rays only
                  #= # times longer it takes for you to get erythema than without sunscreen
                  MED=smallest dose of VUR (hrs) which causes erythema or sunburn
                        SPF = MED with sunscreen/MED without sunscreen
          o Factors that can change SPF
                  Amount of sunscreen, sweat, water, formula, frequency of application, towel drying

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Physical Sunscreens
   - Reflect or scatters UV radiation
   - Not measured by SPF
          o Ex/ Titanium Dioxide, Zinc oxide
          o Pros: Broad spectrum converage, chemically inert, safe
          o Cons: discolor clothing, occlude skin, appears white/visible on skin
Chemical Sunscreens:
   - Works at basal layer (“sun” tanning)
   - Ctive ingredients that absorb, filter, & reduce UVR penetration
   - UVB – measured by SPF
   - UVA – no easy measuring system

UVC 200-290nm
   - Mutagenic, carcinogenic
   - Can be emitted by artificial UV sources
   - Does not stimulate tanning
   - Doesn’t reach earth’s surface
UVB: 290-320nm
   - Penetrates through stratum corneum & dermis
   - Cause erythema, sunburn & skin cancer
   - Responsible for Vit D3 synthesis
UVC: 320-400nm (I: 340-400nm, II: 320-340nm(
   - Penetrates deep into tissue (elastin & collagen)
   - Causes vascular damage, photoaging (premature aging and wrinkles
   - Effecs relating to cataracts, immunologic effects, cancer)
   -
Class                  Examples                    UVB/UVA Protection (nm)         Pros                         Cons
PABA                   (Para-Aminobenzoic          UVB (260-313nm)                 Water resistance (binds to   - Not as effective as
                       Acid)                                                       epidermal cells)             newer agents
                                                                                                                - Not water soluble
                                                                                                                (must be in alcohol
                                                                                                                base solution)
                                                                                                                - Contact
                                                                                                                sensitiviy/Allergic
                                                                                                                reactions
                                                                                                                - Discolors cotton &

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                                                                                                                     fabrics
PABA Esters           Padimate-O; Padimate-A,            UVB (260-315nm)              -Fairly water resistant        “PABA” derivative
                      glycerol PABA                                                   - Doesn’t stain clothes
                                                                                      - Less allergic reactions
Cinnamates            Octinoxate*                        UVB (280-310nm)              - Doesn’t stain clothes        - Less potent than other
                      *most frequently used ingredient                                - Not water soluble (can be    UVB absorbers
                      Cinoxate                                                        used in more water resistant   - Used in combo
                      Diethanolamine
                      Methoxycinnamate
                                                                                      formulas)
Salicylates           Octisalate                         UVB (290-315nm)              -Stable in sunlight            - Weaker absorber than
                      Homosalate                                                      -Water insoluble               PABA
                      Trolamine salicylate                                                                           - Added to other
                                                                                                                     ingredients to boost
                                                                                                                     SPF
                                                                                                                     - Used in higher conc.
Octocrylene                                              UVB                                                         - Used in combo
                                                                                                                     Stabilizesthe
                                                                                                                     photodegredation of
                                                                                                                     other ingredients (ie.
                                                                                                                     Avobenzone)
2-                    Ensulizole                         Selective UVB filter         - Water soluble & used in      - Used in combo
PHenylbenzimidazole   Eusolex 232                        - Allows almost all UVA to   products to make less oily,
5-Sulphonic Acid      Novantisol                         transmit                     feel lighter
Benzhophenones        Oxybenzone                         UVB/UVB (partially)          - Doesn’t stain clothes        - Allergic reactions
                      Dioxybenzone                       320-350nm                    - “Broad spectrum” (also       - Not water resistant
                                                                                      absorbs UVA-II)                - Used in combo to
                                                                                      - Also fxn as preservative,    boost SPF
                                                                                      protecting against
                                                                                      discoloration in other
                                                                                      products
Anthranilates         Meradimate                         UVA (322-350nm)              - Less sensitivity reactions   - Less effective than
                                                                                      - Absorbs mainly UVA           benzophenones in
                                                                                                                     UVA, so less widely
                                                                                                                     used
Dibenzoylmethanes     Avobenzone                         UVA I & II (310-400nm)       - Doesn’t stain clothing       - Photo-unstable (use
                                                                                      No skin irritation             octocrylene – UVB- to
                                                                                                                     stabilize avobenzone)
                                                                                                                     - May degrade other
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                                                                                                                 ingredients in products
Benzylidene           Ecamsule                    UVA (320-340nm)                -Protect in near UVA range      - Water soluble (less
derivative            (currently found in                                                                        water resistant)
                      Anthelios SX only)                                                                         - Photo-unstable (use
                                                                                                                 octocrylene to
                                                                                                                 stabilize)

UVA & UVB Protection: New Products
  (1) Anthelios SX
         a. UVA (up to 344nm)
         b. Photostable
         c. Combines mexoryl SX + octocrylene + avobenzone
  (2) Helioplex
         a. Helioplex (ie. Octocrylene?) stablitizes UV blockers, avobenzone & oxybenzone
         b. Dry-Touch technology to absorb excess sunscreen oils
         c. Water- & sweat-proof
         d. PABA-free

Suntan oils & Gelees
  - Allows a mild short-lived tan with minimal sunburn protection
  - Contains lower concentration of active ingredients
  - Ex/ Coppertone Gold, Banana Boat Dark

Sunless Tanning
  - Works at Stratum Corneum layer of epidermis
  - Tans in 2-3 hrs without sun damage
  - Lasts about 5-7 days; removed by normal flaking of skin
  - Reapply every 3 days to maintain tan
  - Apply more in thicker skin areas

(1) DHA (Dihydroxacetone)                                               - Side effects: hepatitis, canthanxanthin retinopathy
    - Natural sugar
    - Colors or darken the skin by “dying” the surface
          o Reacts with keratin protein in top layer of skin            (3) Bronzers
          o Produces a brownish pigment (melanoidin)                             e. Powers & moisturizers
(2) Tanning Pills                                                                f. Tints or stains skin
- Contains canthaxanthin, which turns skin orange-brown once                     g. Can be removed with soap & water
consumed
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Drugs that cause Photosensitivity
   - Antihistamines
   - Coal & Tar derivatives
   - Oral contraceptives with estrogen
   - NSAIDs
   - Phenothiazines
   - Sulfonaminds/Sulfonylureas
   - Thiazide diuretics
   - Tetracycline
   - Tricyclic anti-depressants




Treating Sunburn
   - Cool moist compresses
   - Aloe vera gels
   - Cool oatmeal bath
   - Aspirin or Motrin
   - Topical Anesthesic sprays
   - Protect blisters
   - Water
   - Starch in raw potatoes




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