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SKIN CARE

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SKIN CARE

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  1. SKIN CARE TRAINING Alain KHAIAT, Ph. D. Vice President R&D Asia Pacific

  2. TRAINING CONTENT • Skin physiology • Cosmetic functions: • mechanism • ingredients used • performance assessment

  3. Skin • Is the external barrier of the body, both physical and immunological • Is the mirror of the state of health of the body Skin plays an essential role both in the aesthetic and health field.

  4. SKIN PHYSIOLOGY The skin is the outer most layer of the body. It is constituted of 2 layers : • epidermis • dermis which sit on the fat layer around the muscles.

  5. EPIDERMIS The stratum corneum made essentially of dead cells is exfoliating. The space between the cells constitutes the intercellular cement.

  6. DERMIS The dermis is where the collagen and elastin fibers are. These fibers are responsible for the skin structure and elasticity. They are degraded by enzymes called collagenase and elastase which belong to the class of “Matrix Metallo Proteases” or MMP.

  7. OIL PRODUCTION • Oil is produced in the sebaceous gland , production is stimulated by hormones • Oil flows into the hair follicle then onto the skin surface

  8. Normal hair follicle where sebum empties onto skin surface through follicle opening Oil Production

  9. COMEDONES • Whiteheads are closed comedones. The obstructed follicle prevents oil flow and provides an oil reservoir for bacterial growth. They lead to inflammation • Blackheads are open comedones (follicle obstruction). The color is melanin and oxidized lipids, not dirt. The content is firm and dilates the follicle, blackheads are not inflammatory

  10. COMEDONES Whiteheadsor closed comedones • stays beneath the skin. Slightly raised, light coloured lesion • Caused by build up of debris ( cells + sebum) within follicle • Blackheads oropen comedones • a whitehead becomes a blackhead when • it enlarges until a dark plug protrudes through the skin surface • * Both whiteheads and blackheads may stay on the skin for a long time. • * Whiteheads and Blackheads are non-inflammatory

  11. SOLAR SPECTRUM

  12. UVB DAMAGE • UVB impact on DNA in the cell creating damages which may lead to cancer • P53 gene codes for a protein that allows repair of the DNA or kill the cell if repair is not possible: “sunburn cells”

  13. UVA DAMAGE • UVA acts through an oxidative stress, forming free radicals (reactive oxygen species) that will damage the DNA • Reactive oxygen species create damages leading to cancer • Pigment production is the defense mechanism

  14. TRAINING CONTENT • Skin physiology • Cosmetic functions: • mechanism • ingredients used • performance assessment

  15. COSMETICS DEFINITION : Products applied on the skin, hair, teeth or teguments in order to : • beautify • perfume • cleanse • promote attractiveness • alter the appearance

  16. COSMETICS : FUNCTIONS • Cleansing • Moisturizing • UV protection • Aging - Wrinkle • Acne & Oily skin • Pigmentation

  17. CLEANSING • Soap : high pH, low rinsability, high irritation • Some soap have high rinsability, low irritation • Cream cleanser / Facial wash : • rinse off : detergent-based, neutral pH, irritation depends on detergent type and concentration • tissue off : leave on, emulsion-based, less “fresh clean feel“

  18. RINSABILITY • Measured by Fourrier Transform Infra Red or FTIR : scanning of the skin before application and after rinsing of a cleanser. The difference is representative of the quantity of product left on the skin. • Digital imaging with proper light allows also to evaluate rinsability

  19. IRRITATION • Patch test • Chromameter (red color) • Trans epidermal water loss : TEWL

  20. CLEANSER FORMULA • A typical cleanser formula consists of : • detergent 10 - 15 % • foam booster 0 - 2% • preservative < 1 % • fragrance 0 - 1% • water Qs 100 %

  21. CLEANSER FORMULA • Surfactants : usually combinations are used to enhance lathering and reduce irritation. SLS is to be avoided, it strips the skin of its lipids contributing to irritation. • Preservatives : allergy potential of formaldehyde donors. • Fragrance : known allergens (like Peru Balsam or MuskAmbrette) have been banned. It is important for the fragrance to meet IFRA guidelines

  22. MOISTURIZING • Water, like air or light, is essential to life • Moisturization is a woman’s main expectation from a cosmetic product • Dermatologists face dry skin condition every day : physiological, pathological (ichthyosis), therapeutic (PUVA, retinoids)

  23. WHERE IS THE WATER ? • 50% is intracellular • 15% is extracellular • 5% is plasmatic • 30% is in the sweat glands

  24. MECHANISMS OF REGULATION • Hydration through deeper layers • Loss through evaporation • Moisture retaining ability of the stratum corneum, dependent on : • Hydro Lipido Proteic film (HLP) • Natural Moisturizing Factor (NMF) • integrity of intercellular cement

  25. HLP FILM • Originates from sebum and sweat secretions • Composed of : • water - triglycerides • ions - cholesterol free & esterified • amino acids - squalene • urea - fatty acids - waxes

  26. NMF • Amino acids • Urocanic acid • Pyrollidone carboxylic acid : PCA • Electrolytes • Sugars

  27. INTERCELLULAR CEMENT • Ceramides ( sphingolipides ) • Fatty acids ( Linoleic acid ) • Cholesterol ( free & esters )

  28. MOISTURIZING INGREDIENTS • Occlusive agents • Structural lipids • Hydrophilic film forming agents • Humectants • NMF • AHA

  29. OCCLUSIVE AGENTS • Vaseline, paraffin • Waxes of animal or plant origin • Some silicone oils or waxes • Some vegetable oil (sweet almond) • Some fatty esters (isopropyl myristate) • Fatty alcohols older technique, often comedogenic

  30. STRUCTURAL LIPIDS • Essential Fatty Acids (EFA : linoleic, linolenic acids) • Poly unsaturated fatty acids (PUFA : EPA, DHA) • Ceramides or pseudo ceramides • Cholesterol

  31. HYDROPHILIC FILM FORMING AGENTS • GAG : glycosaminoglycans like Hyaluronic acid or chondroitin sulfates • Collagen • Proteins • Chitin or Chitosan

  32. HUMECTANTS • Glycerin • Propylene Glycol or Butylene Glycol • Sugars

  33. NMF • PCA • Urea (below 10 %) • Amino Acids or hydrolyzed protein

  34. AHA At low concentration (< 2 % ) AHA are moisturizing agents by creating hydrogen bonds between the protein chains. The most common are : • glycolic acid • lactic acid • citric acid • malic acid

  35. PERFORMANCE ASSESSMENT • FTIR :the ratio of amide I to amide II peaks is function of the skin hydration • NMR : nuclear magnetic resonance • TEWL : trans epidermal water loss • Capacitance (Corneometer®) • Conductance (Skicon®)

  36. FORMULATION • Typically they are oil in water emulsions : • water • propylene glycol : penetration enhancer it becomes irritating above 5% • humectants, film forming agents, AHA, NMF • emulsifiers : could contribute to irritation, concentration to be kept to a minimum • oils, fatty esters : some are comedogenic

  37. UV PROTECTION Two types of filters are used : • chemical • mineral

  38. SOLAR SPECTRUM

  39. CHEMICAL FILTERS • Limited spectrum, highly regulated • Most common filters : • cinnamates (UVB) • PABA (UVB) • Oxybenzone (UVA) • Avobenzone (UVA)

  40. MINERAL FILTERS • Broad spectrum, filtering capacity function of size, influence on product texture • Most common filters : • TiO2 • ZnO

  41. PERFORMANCE ASSESSEMENT • SPF measurement in vivo : it is the ratio of the minimum erythemal dose with and without protection ( relates only to UVB protection ) • in vitro measurements : • Diffey method • spectrophotometric absorption method

  42. AGING : INTRINSIC • Program theory : each cell contains a clock which control the number of multiplication • Error theory : occurrence of errors in the replication which eventually lead to cell death • Control theory : cells function is remotely controlled by secretions ( hormones )

  43. AGING : EXTRINSIC • Sun : UVA / UVB / IR • Psycho social factors : overwork, stress • Dietary factors : insufficient water supply, vitamin deficiency, alcohol, smoking • Iatrogenic factors : corticosteroids, ionizing radiation, diuretics • Pathological factors : genodermatose, acrogenia • Hormonal factor : menopause

  44. MANIFESTATIONS OF SKIN AGING • Epidermis : • reduction in cell renewal rate • thickening of stratum corneum • decrease in barrier efficiency : increase in TEWL and hyperkeratosis • ridges are flattened out and intercellular spaces enlarged • pigmentation problems : actinic lentigines • decrease in skin immune system

  45. MANIFESTATIONS OF SKIN AGING • Sebaceous glands : • reduction in sebum secretion (hormones influenced) • Sweat glands : • less active • HLP film : • thinning of film means less protective barrier

  46. MANIFESTATION OF SKIN AGING • Dermis : • destruction of collagen and elastin fibers network • proteoglycans and glycoproteins are reduced • increase in elastin synthesis : elastosis

  47. WRINKLES • Expression lines : • they are the first manifestation • due to constant creasing of the face • accentuated by environmental factors • they appear around the eyes (crow’s feet), the nose and mouth (naso-labial fold), forehead (frown lines)

  48. WRINKLES • Gravity lines : • skin and muscle structure become slack and droops downwards • subcutaneous tissues tend to sag • flabby cheeks, double chin, bags under the eyes and drooping eyelids