Skin Physical Enhancers & Skin Hydration

Question 1

Is it still a cosmetic if we inject something into the skin?

Answer 1

No. It is only a cosmetic if it is applied to the external surface of skin

Question 2

What are physical enhancers

Answer 2

They are an alternative to chemical enhancers to disrupt the SC for delivery of large molecules
e.g. iontophoresis, ultrasound, electroporation, thermal ablation, microneedles

Question 3

What is iontophoresis

Answer 3

Acts by applying a small electric current to the skin

e.g. used for those who have overactive sweat glands

Question 4

What about ultrasounds

Answer 4

Makes use of ultrasound waves that generate small bubbles of water on the surface of the skin
safer alternative to liposuction

Question 5

What is thermal ablation

Answer 5

Applies localised heat for a short period of time to create microscale pores across the SC

Question 6

What are microneedles

Answer 6

Some are permanent while some are dissolvable

length rather than density of microneedle is more impt bc if its too long it may hit the nerve

Question 7

How does skin hydration work?

Answer 7

Stratum corneum: water content is 15-20%
Viable epidermis: water content is 70%

water gradient allows lipids to provide an optimal way to replenish water within skin

Question 8

What is TEWL (Transepidermal water loss)?

Answer 8

indirect measure of how good the SC is as a barrier
higher the reading, higher the loss of water
readings would be diff in diff ctys (due to temp & humidity diff) therefore need a baseline when comparing

Question 9

What are the 2 basic formulations of cosmetics?

Answer 9

1. Oil-in-water (water as dominant phase)

2. water-in-oil (oil as dominant phase)

Question 10

What are the main ingredients in cosmetics for skin hydration?

Answer 10

1. Occlusive agents
   - forms a barrier across skin to lock water e.g. petrolatum & ceramides
2. Humectants
   - attracts & hold water to be within skin e.g. NMFs, glycerin
3. Emollients
   - fill the space between desquamating corneocytes with droplets
4. Hydrophillic matrices
5. Sunscreens
6. Charged surfectants

Question 11

Give some e.g. of occlusives

Answer 11

They retard TEWL but do not allow SC to repair its barrier function
e.g. petrolatum, lanolin, lecithin, cholesterol

Question 12

Humectants

Answer 12

Absorbs water from surroundings, drags water to skin

e.g. glycerin/glycol, hyaluronic acid, urea, sodium lactate, PCA

Question 13

Glycerine

Answer 13

Humectant
Part of the NMF present in skin
used as a preservative

Question 14

Lactic Acid

Answer 14

Humectant

is an AHA, exfoliating agent

Question 15

Urea

Answer 15

Humectant

Question 16

Propylene Glycol

Answer 16

Antimicrobial agent
used as a solvent
chemical skin permeation enhancer

Question 17

Butylene glycol

Answer 17

Preservative

used in hair sprays as it retards loss of aromas and keeps away moisture so the hair stays

Question 18

Panthenol

Answer 18

aka provitamin B5
moisturising, soothing & sedative properties
particular affinity with hair

Question 19

Pyrrolidone Carboxylic Acid (PCA)

Answer 19

Naturally occurring humectant in SC, NMF

Question 20

What are hydrophillic matrices?

Answer 20

Large molecular weight substances that retard TEWL

e.g. hyaluronic acid and vitamins

Question 21

Hyaluronic Acid

Answer 21

Absorbs up to 1000x its own weight

gives mechanical support to skin

Question 22

Proteins & amino acids

Answer 22

belong to NMFs

most widely used protein types are hydrolysed proteins

Question 23

What does staying in water for too long do to the skin?

Answer 23

negatively affects SC barrier function

causes SC swelling and weakens corneocyte cohesion

Question 24

What is desquemation?

Answer 24

Exfoliation, SC normally takes 1 mth to go
to speed up the process, we use lactic acid/micro beads/microneedles to exfoliate
slows down with age

Question 25

How do emollients work?

Answer 25

Function by filling the space between the desquemated corneocytes with oil droplets
e.g. castor oil, sesame oil, diisopropyl dilinoleate