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Skin Care Ingredients & Formulations > Lecture 4 - Moisturizers and Moisturization > Flashcards

Lecture 4 - Moisturizers and Moisturization Flashcards

1
Q

characteristics of normal skin vs. dry skin

A 
Normal
-Even texture and tone
-Smooth surface
-Supple plump feel
-Free of irritation
Dry
-Rough & scaly surface
-Flaky , large squames
-Tight  feel
-Inflamed , red , blotchy, itchy
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2
Q

external factors of dry skin

A
  • Low relative humidity in dry environments- winter , airplane
  • Wind and air currents causing evaporation
  • Soap & detergent stripping skin lipids
  • Solvents – alcohol , acetone strip lipids
  • Inflammation caused by UVR (ultraviolet radiation)
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3
Q

intrinsic factors of dry skin

A
  • Impaired SC function
  • Reduced sebum production
    (eg. in aging skin)
  • Dietary deficiency of EFA (essential fatty acids- PUFA –polyunsaturated FA)
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4
Q

What 3 things happen with impaired SC function?

A
  • Increased TEWL (trans epidermal water loss)
  • Abnormal keratinization and desquammation
  • Reduced levels of NMF (natural moisturizing factor)
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5
Q

top 5 causes of dry, dehydrated skin (according to alpha keri)

A
  1. Aging
  2. Over-cleansing (excessive bathing, scrubbing, use of soap)
  3. Extreme climatic conditions
  4. Prolonged sun exposure
  5. Lifestyle (poor diet, nutritional deficiencies, certain medical conditions and medications)
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6
Q

parameters to formulate effective moisturizers

A
  • Key ingredients: emollients, occlusive agents, humectants
  • Vehicle type: o/w, w/o emulsions, lamellar gel systems
  • Ingredients are selected accordingly, depending on the vehicle type and the application target (face or body)
  • Cosmetic forms: lotions, creams, oils, milks, serums, sprays, gels
  • Targeted type of skin: normal, dry, sensitive, oily
  • Marketing regimen: facial, hands and body
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7
Q

define emollients

A

provide partial occlusion that soothes, moisturizes and improves the appearance of the SC by masking the rough, scaly skin condition and reducing the sensation of itching

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8
Q

define occlusive agents

A

form a film on the surface of the skin and moisturize by retarding the evaporation of water (TEWL) from the skin surface

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9
Q

define humectants

A

bind water from the environment and help by retaining water in equilibrium within the skin

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10
Q

define enhancers of skin barrier

A

mimic the SC bilayers structure and assure long-lasting moisturization

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11
Q

What are emollients vs. moisturizers

A 
Emollients
-Lubrication
-Skin “smoothing” & softening
-Effect skin feel
Moisturizers
-Water retention
-Humectancy
-Barrier activity-Reduce water loss
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12
Q

Characteristics of emollients - physical forms (4 types)

A
  • varying viscosity liquids
  • soft solids - butters
  • waxes
  • cationic fatty compounds
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13
Q

5 categories of ingredients in emollients

A 
Silicones
Triglycerides
Esters
Hydrocarbons
Ethers
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14
Q

9 criteria of selecting emollient esters and occlusive ingredients

A
  • Chemical structure
  • Polarity( Solubility Parameter)
  • Spreading behavior
  • Molecular weight
  • Viscosity
  • Hydrolytic stability
  • Solubilizing behavior towards oil-soluble solids
  • Permeability into skin
  • Moisture retention
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15
Q

type of spreading with high mw esters vs low mw esters

A

— High MW esters deliver low spreading

— Low MW esters deliver high spreading

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16
Q

type of spreading with high visc vs low visc

A
  • low visc = high spreading

- high visc = low spreading

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17
Q

Spreading values provide information about the_____ of an emollient

A

fatty character (alkyl chain portion)

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18
Q

types of hydrocarbon emollients

A 
Mineral Oil-most popular
PAOs
Polyisobutenes
Isoparaffins
Petrolatum
Paraffin, ozokerite & microcrystalline waxes
Squalane – natural derived
19
Q

Pros/cons of mineral oil

A

Pluses
- Most ubiquitous emollient-most common viscosity is 70 vis.
- More than a century of common use-internally & externally
- Inexpensive
Minuses
- Anti-mineral Oil attitudes - “clogs pores”, “de-fats the skin”, dermatologists
- No “Oil Free” Claims

20
Q

define fixed oils

A

liquid triglycerides – fatty acid storage in oil seeds

21
Q

define butters & fats

A

semi-solid triglycerides – usually melting above or near ambient temperature

22
Q

define waxes

A

distinctly solid lipids primarily fatty acid esters (& also used to describe hydrogenated oils that have elevated melting points)

23
Q

lanolin (unique emollient/emulsifier)

A
  • Classified as a wax – composed of alcohol & sterol esters – “wool wax”
  • Absorbs and retains high levels of water
  • Self emulsifying W/O base – standardized by water absorption method
  • Issues with animal origin and potential residual pesticides
24
Q

4 other naturally derived emollients

A

CCT ( Capric/Caprylic Triglyceride)
Squalane
Jojoba Wax & hydrogenation
Myristyl Myristate

25
Q

how is an ester formed

A

from reaction between an fatty acid and a fatty alcohol

Undergo hydrolysis at extreme pH’s (high or low) and elevated temperature

26
Q

define spreading coefficient (S) of a liquid

A

determines how well that liquid will wet the surface (skin) when is applied

27
Q

Spreading characteristic of an ester is dependent on its (what 3 things)

A

— chemical structure
— molecular weight (MW)
— viscosity

28
Q

Chemical structure of an ester dictates the initial feel - how?

A

— Linear or unbranched esters tend to enhance slip or lubricity and can be heavy
— Branched chain esters tend to have a dry initial feel and spread easily

29
Q

define spreading value

A

Surface area (mm2) covered in a specific time by the emollient (in vivo – human skin forearm, in vitro – VitroSkin etc.)

30
Q

name very high spreading esters with a light, dry after - feel

A 
— Diiso.propyl Adipate
— Di-butyl Adipate
— Hexyl Laurate
— Isopropyl Myristate
— Isopropyl Palmitate
— Isopropyl Isostearate
31
Q

name high spreading esters with an elegant/velvety after feel

A

— Tridecyl Neopentanoate
— Isostearyl Neopentanoate
— Isodecyl Neopentanoate

32
Q

name medium spreading esters with medium after feel

A

— Isocetyl Stearate

— Cetearyl Isononanoate

33
Q

silicones (general)

A

Silicone is a generic name for many classes of organo-silicone polymers with repeating siloxane (Si-0) units

Have a wide range of MW

34
Q

silicone structure can be…

A

Cyclic, linear and cross-linked

Volatile or non-volatile

35
Q

Silicone fluids are used because

A
  • Are very resistant to high temperatures
  • Very resistant to oxidation
  • Are easily spreadable forming “breathable” films
  • Good detackifiers reducing tackiness
36
Q

types of hydrophilic emollients

A

Water soluble polymers & waxes- i.e.PEGs
Silicone copolyols
PEG esters
Ethoxylated alcohols & naturals (lanolin)

37
Q

characteristics of humectants

A
  • Attract and retain water- Hygroscopic
  • Hydrogen bonding groups – Hydroxyl groups
  • Act as freeze point depressants
  • Act as skin moisturizers depending on RH
  • Maintain an equilibrium with water vapor in air
38
Q

characteristics of glycerol

A 
- The most common used humectant in personal care
— Used between 2-25% in moisturizers to treat dry skin
- Heavy and tacky feel
— Excellent skin tolerability ;
— Low cost
— Help wound healing in skin
— Desquamation
— Skin barrier recovery
- Anti-irritant
39
Q

characteristics of Pyrrolidone Carboxylic Acid

A

Sodium PCA- “Natural Moisturizing factor”NMF
Found in the skin
Extremely Hygroscopic
Extremely safe, even at high conc.
Very stable to broad range of pH and temp

40
Q

characteristics of hyaluronic acid

A

Glycosaminoglycan
The most efficient “moisturizer”
Ubiquitous to humans- connective tissue, vitreous fluid of eyes,dermis
Most commonly used material made from bacterial fermentation
Medical grades also from Rooster combs
Film former/ retains water

41
Q

types of Moisturization Efficacy Testing

A

Trained graders: dry flaky skin
D-Squame tape grading- SC flakes
Conductivity & Impedance meters (NOVA Meter, Skicon Corneometer )
TEWL (Trans Epidermal Water Loss)
Macrophotography- grading before & after
Skin replicas- image analysis

42
Q

types of Bioengineering Instrumentation

A

Moisture testing – direct and indirect –TEWL
Skin Friction – hydrated skin > dry skin
Skin Elasticity Resiliency- Cutometer, Twistometer, Ballistometer
Skin pH • Skin surface temperature IR scan
Sebumeter- surface oil by light diffraction
Skin tone – Chromameter ( L,a,b values)
Laser Doppler blood flow- erythema, vasodilation
Skin Topography- Profilometry-wrinkle number, length, depth (“reduces fine lines”)
Image Analysis – direct/ indirect replicas
Microscopy: Light, Con-focal, SEM

43
Q

moisturizers treat dry skin rehydrate and restore the skin barrier by using…

A

— Occlusive agents which seal skin to prevent water loss
— Emollients provide semi-occlusive films; also act as plasticizers and feel modifiers
— Humectants attract and hold water (similar to NMF)
— Enhancers of skin barrier to replenish damaged lipids and reinforce the skin’s natural lipid barrier function

Skin Care Ingredients & Formulations (7 decks)

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