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PR2202 > Chapter 4 - Skin Physical Enhancers and Skin Hydration > Flashcards

Chapter 4 - Skin Physical Enhancers and Skin Hydration Flashcards

1
Q

What are the 5 physical penetration enhancers?

A

(1) Iontophoresis
(2) Ultrasound
(3) Electroporation
(4) Thermal ablation
(5) Microneedles

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2
Q

How does physical penetration enhancers differ from chemical penetration enhancers?

A

Physical penetration enhancers disrupt the stratum corneum for the delivery of larger molecules
Chemical enhancers are restricted to the gaps in the stratum corneum.

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3
Q

How does iontophoresis work and what size molecules does it allow to pass through?

A

It involves the application of a small electric current to the skin (< 500 µA/cm2) for charged particles to diffuse across. Applicable for molecules < 7,000 Da via the repulsion of similarly charged ions through the skin

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4
Q

Who started using cathaphoresis (a type of iontophoresis)?

A

Ruth D. Maurer who began Marinello Beauty salon (1871 - 1945)

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5
Q

How does ultrasound work?

A

Ultrasound waves generate small bubbles of water on the skin surface. These bubbles burst and the vibration allows penetration. Improve skin permeability up to 24 hours.

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6
Q

What is the limitation of ultrasound?

A

Some substances like sodium dodecyl sulfate get degraded under ultrasound.

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7
Q

How does electrophoresis work?

A

Electrophoresis utilizes high voltage (≥ 100 V) for (10 µs to 100 ms) to create transient pores.

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8
Q

What are the precautionary measures when using electrophoresis?

A

Duration of the application must be very short as it can cause muscle contraction. Although the electric field is located at the stratum corneum, it can affect deeper tissues and cause pain and muscle contractions.

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9
Q

How does thermal ablation work?

A

Thermal ablation applies localized heat for a short period of time to create microscale pore across the stratum corneum. Heat from radiofrequency, electrical heating elements and lasers

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10
Q

What are the precautionary measures when using thermal ablation?

A

Max temperature of 100 degrees (ms or shorter). Localization to avoid damage.

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11
Q

How do microneedles work?

A

micron scale needles that are the hybrid between transdermal patches and efficient hypodermic injections

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12
Q

What are the dissolvable microneedles called?

A

Hyaluronic acid microneedle

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13
Q

What is the difference in the water content of the viable epidermis and the stratum corneum?

A

Viable epidermis - 70% water

stratum corneum - 15-30% water

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14
Q

How is the water gradient between the epidermis and stratum corneum good?

A

The lipids provide an optimal way to replenish water within the skin.
Water escaping the stratum corneum need to traverse through the lamellar lipids thus helps in reducing water loss to the atmosphere

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15
Q

What is TEWL and what does it measure?

A

TransEpidermal Water Loss (TEWL). It measures the density gradient of water evaporation from the skin indirectly.

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16
Q

What is the use of TEWL?

A

TEWL is useful for identifying skin diseases. TEWL increase in proporton to the level of damage.

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17
Q

What are the natural moisturizers present in the skin and its locality?

A

NMF - In the corneocytes of stratum corneum.
HA - In the dermis and stratum spinousum, acting as a humectant
Aquaporin-3 - Proteins that form water channels across cell membranes (Low aquaporin-3 = dry skin)
Glycerol - Endogenous glycerol from sebaceous gland

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18
Q

What are NMFs?

A

NMF = Natural Moisturizing Factors

They contain a number of other hydrophilic agents (20-30% dry weight of the stratum corneum.

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19
Q

What are examples of NMF?

A

Examples include:

(1) Amino acids
(2) Sodium pyrrolidone carboxylic acid
(3) Lactate
(4) Urea
(5) Ions
(6) Sugars
(7) Ammonia, uric acid , glucosamine, creatine
(8) Citrate and formate

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20
Q

What are tight junctions?

A

They consist of proteins (claudins) which form a semipermeable barrier between cell membranes, preventing water from passing through the space between the epidermal cells.

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21
Q

What do moisturizers usually contain?

A

Water (60-80%), lipids, emulsifiers, preservatives, fragrance, and color

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22
Q

When are oil-in-water emulsion used?

A

Water dominant phase. Usually used for day-time creams. Feels cool and have a nonglossy appearance, usually with mineral oil and propylene glycol and water.

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23
Q

When are water-in-oil emulsion used?

A

Oil dominant phase. Usually used for night creams (made of mineral oil, lanolin alcohol, petrolatum and water to give glossy appearance)

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24
Q

What are the most used preservatives in moisturizers?

A

Parabens

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25
Q

Define what is surfactants and its application.

A

Surfactants are compounds that lower the surface tension between 2 liquids or a liquid and a solid. They are anionic and cationic and are very aggressive in damaging the skin barrier. A common surfactant is SLS (sodium lauryl sulfate)

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26
Q

How does surfactant affect skin hydration?

A

Surfactants removes NMF

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27
Q

Name three examples of anionic surfactants.

A

sodium stearate, sodium oleate, sodium dodecyl sulphate (SLS)

28
Q

Name two examples of cationic surfactants

A

Dodecylamine hydrochloride, hexadecyltrimethyl ammonium bromide

29
Q

Name three examples of nonionic surfactants.

A

Polyethylene oxides, Spans (sorbitan esters), tweens (polyoxyethylene sorbitan esters)

30
Q

Name one ampholytic surfactant.

A

Dodecyl betaine

31
Q

What is the function of occlusive agents?

A

Form a barrier across skin to lock water. They lower TEWL. Do not allow the SC to repair its barrier function,

32
Q

What types of occlusive agents are there? Name all examples for each type.

A

(1) Oils and waxes - petrolatum and paraffines
(2) Fatty acids - lanolin (lips) and ceramide
(3) Phospholipids - lecithin
(4) Sterols - cholesterol
(5) Others - dimethicone, mineral oil, propylene glycol diloleate

33
Q

What is the function of humectants?

A

Absorb water from surroundings and allow skin to feel smoother by filling holes in the SC through swelling. The hydroxyl group forms hydrogen bonds with water from the environment

34
Q

When is occlusive favored over humectants?

A

When there is low humidity, water in the surrounding is low. Need occlusive to prevent water loss

35
Q

Name six examples of humectants.

A

Glycerin, honey, sodium lactate, urea, propylene glycol, pyrrolidone carboxylic acid (PCA)

36
Q

Which NMF also function as humectants?

A

(1) Pyrrolidone carboxylic acid (PCA)
(2) Urea
(3) Lactate

37
Q

What should a good moisturizer have?

A

A combination of occlusive and humectant properties

38
Q

What are hydrophilic matrices?

A

They are high molecular weight molecules that lower TEWL.

39
Q

How do sunscreens prevent dehydration?

A

Sunscreens are considered moisturising ingredients because they prevent cellular damage and thus prevent dehydration.

40
Q

What do emollients do? Name examples.

A

(1) They fill the space between the desquamating corneocytes with oil droplets and make skin feel smooth and soft.
(2) Almond butter or shea butter, dimethicone, petroleum jelly, mineral oil.

41
Q

What is the difference between humectants and emollients?

A

Humectants bonds with water moles to increase water content of skin while emollients are used to soften and smooth the scales of the skin, reduce rough flaky skin.

42
Q

What is hygroscopic?

A

Tending to absorb moisture from the air

43
Q

What are the properties of glycerin?

A
  • Molecular weight = 92.1, aka glycerol and 1,2,3 –propanetriol.
  • Clear, colorless, odorless, syrupy and hygroscopic liquid.
  • Miscible with water and alcohol.
  • Used as a solvent, plasticizer, sweetener, lubricant and preservative. Concentrated solutions of glycerin are used in suppositories with glycerin promote fecal evacuation.
  • As moisturizers, 20-25% are used. It interacts with stratum corenum lipids by perturbing the lipid crystalline structure.
  • Glycerin dropped on human eye causes a strong stinging and burning sensation but has excellent skin tolerability.
44
Q

What are the properties of lactic acid (NMF)?

A
  • Molecular weight = 90.1.
  • Colorless to yellowish crystal or liquid, miscible with water, alcohol and glycerin.
  • It is an alpha-hydroxy acid (AHA).
  • It is a component of natural hygroscopic material of stratum corneum, constituting about 12%.
  • Used in topical preparation because of its buffering properties and water-binding capacity (i.e. as exfoliant and humectant).
  • FDA recommends maximum level of 2.5% and pH 5.
45
Q

What are the properties of urea (NMF)?

A
  • Molecular weight = 60.08. Also called carbamide.
  • Colorless, slightly hygroscopic, odorless crystal. Urea hydrolyzes in water to ammonia and carbon dioxide.
  • Freely soluble in water, slightly soluble in alcohol.
  • It is used as a cream in higher concentration (10%) to treat skin diseases and a lower concentration to treat dry skin.
46
Q

What are the properties of propylene glycol?

A
  • Molecular weight = 76.1, aka 1,2 –propanetriol.
  • Clear, colorless, viscous liquid with a sweet and slightly acrid taste resembling glycerin.
  • Miscible with glycerin, water, and alcohol.
  • Used as a solvent, especially for substances unstable or insoluble in water. Also used in food, anti-freeze and emulsifier. And an inhibitor of mold growth.
  • Skin applications include treatment of skin disorders and chemical skin permeation enhancers.
  • Safe to use in cosmetic products below 10%.
47
Q

What are the properties of butylene glycol?

A
  • Molecularweight=90.1,aka1,3–butanediol.
  • Viscous, colorless liquid with sweet and bitter flavor.
  • Soluble in water, acetone and castor oil.
  • Used as a humectant for tobacco. Also used as a solvent for injectable products.
  • For cosmetics, it is used in hair sprays and setting lotions. It also retards loss of aromas and preserves cosmetics against spoilage by microorganisms.
  • Safe for skin applications and less irritating than propylene glycol.
48
Q

What are the properties of panthenol?

A
  • Molecularweight=205.3, aka provitamin B5.
  • Clear, almost colorless, odorless and viscous hygroscopic liquid.
  • It is converted in tissues to D-pantothenic acid (vitaminB5), a component of coenzyme A in humans.
  • It can be isolated from various living organisms, which gave its name (PanthotenistheGreeknameforeverywhere)
  • Widely used in pharmaceutical and cosmetic industry for its moisturizing, soothing and sedative properties.
  • Accelerate skin barrier repair and decrease skin redness. Found in normal hair and helps hair growth.
  • Safe to use in cosmetics at low concentrations (max2%).
49
Q

What are the properties of sorbitol?

A
  • MW = 182.17
  • white crystalline powder, odorless, and have a fresh and sweet taste
  • soluble in water but not very soluble in alcohol. commonly available in 70% water.
  • used as sweeteners in tablets, candies, diabetic foods, and toothpaste
  • produces a laxative effect when more than 20g is injested in a day
  • inferior hygroscopic properties to glycerin
50
Q

What are the properties of pyrrolidone carboxylic acid* (PCA), a NMF?

A
  • MW = 129.11
  • naturally occurring humectant in SC, about 12% of NMFs
  • sodium salts of PCA are among the most powerful humectants. higher content of PCA in SC is associated with higher moisture-binding abilities.
  • no reported irritation to eyes or skin for concentrations up to 50% in animal studies.
51
Q

Name two examples of hydrophilic matrices.

A

(1) Hyaluronic acid

(2) Vitamins and proteins

52
Q

What are the properties of hyaluronic acid (HA)?

A
  • MW = 50000 - 8000000
  • sits on the surface of the skin and blocks TEWL, and functions as a humectant and hydrophilic matrices
  • hyaluronic acid refers to HA and sodium hyaluronate and is the predominant component of extracellular matrix.
53
Q

What are vitamins A, B3, C, E and K used for?

A

A - wrinkle, B3 - redness, C - spots & antiaging, E - moisture and K - dark circles

54
Q

What is the function of vitamins and proteins in skin hydration?

A

Complement the effect of glycerin by preventing skin water loss

55
Q

What are the properties of collagen?

A
  • main structural protein in the extracellular space
  • has a complex triple helical structure which is responsible for it high moisture retention properties
  • might require strong preservatives, have changes in color and odor
56
Q

What is the most widely used protein types in moisturizers?

A

Hydrolysed proteins of intermediate molecular weight with higher solubility

57
Q

What happens when our skin has prolonged contact with water?

A
  • affect stratum corneum barrier function, similar to surfactants
  • elicit erythema (redness), inflammation and dermatitis (redness or irritation)
  • cause stratum corneum swelling and weaken corneocyte cohesion
  • increase the permeability of substances, especially water
  • prolonged hydration of stratum corneum can disrupt the barrier lipids, leading to compromised skin
58
Q

What causes dry skin?

A

Desquamation/exfoliation. Corneocytes are linked by desmosomes, which are macromolecular glycoproteins. As the corneocytes move from the lower layer to the stratum corneum, the desmosomes are progressively degraded by enzymes localized in the intercellular space. Low water content within the stratum corneum affects their activities, leading to dry and flaky skin.

59
Q

How do emollients make skin feel smooth?

A

Emollients function by filling the space between the desquamating corneocytes with oil droplets, so they make the skin feel smooth, although the effect is only temporary.

60
Q

What are the four types of emollients? Give examples for each type.

A

(1) Protective - diisopropyl dilinoleate
(2) Fattening (may be greasy) - castor oil, propylene glycol, jojoba oil, isostearyl isostearate.
(3) Dry - isopropyl palmitate
(4) Astringent - dimethicones, isopropyl myristate

61
Q

What is the definition of complexion?

A

Natural color, texture, and appearance of the skin, especially in the face

62
Q

How is complexion related to skin moisture?

A

Complexion is associated with both the skin color and texture.

63
Q

What kind of complexion is preferred today? How has this changed from the past and across spatial boundaries?

A
  • West preferred tanned complexion in the 1920s
  • East preferred pale skin color
  • Now a young, healthy homogeneous complexion, without imperfection is preferred.
64
Q

What is the function of filaggrin?

A

Filaggrin is a filament-associated protein that binds to keratin fibers.

65
Q

What is the difference between exogenous and endogenous?

A

An exogenous variable (external) is a variable that is not affected by other variables in the system. In contrast, an endogenous variable (internal) is one that is influenced by other factors in the system

66
Q

What are the percentages of the 4 main constituents of NMFs?

A

Amino acids - 40%
Pyrrolidone Carboxylic Acid (PCA) - 12%
Lactate - 12%
Urea - 7%

PR2202 (19 decks)

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