Skin Anatomy, Function, Preparations

Question 1

What are the two main functions of the skin?

Answer 1

Protective barrier to environment

- Prevent fluid loss, entry of foreign body/chems

pH = 4.5-5.5 (acidic mantle)

- Acidity due to fatty/amino/lactic acids/microflora

Question 2

What are some other functions of the skin?

Answer 2

reg temp

synth vit D

protect against UV damage

sensory

blood reservoir

Excretion of unwanted substances through sweat

Question 3

What factors influence skin and its function/anatomy?

Answer 3

Age

immunological status

Underlying disease status

medications (e.g. isotretinoin and drying effect)

Question 4

Outline the characteristics of creams

Answer 4

Viscous semi-solid opaque preparation = contains more additives/preservatives (more reaction risk)

Can be: aqueous cream (oil in water = water miscible) or oily cream (water in oil = oil miscible)

Apply active ingredients to skin = protective, therapeutic, or prophylactic

Question 5

Where can creams be applied?

Answer 5

All areas of body = genitals, flexures, large areas

dry and weepy/exudative skin conditions

Question 6

What are some advantages and disadvantages to creams?

Answer 6

Advantages = easy to spread, not as greasy, moistening, emollient properties

Disadvantages = mostly evaporates or absorbed once rubbed in –> less hydrating than ointment

Question 7

Discuss the properties of ointments

Answer 7

Semi-solid preparations (solutions or dispersions) = hydrophilic greasy base –> form occlusive barrier

Can enhance absorption of some drugs

Question 8

Where can ointments be applied?

Answer 8

areas free from hair (palms, soles)

Areas of short or spares hair

Dry skin of trunk and extremities

Question 9

What are some advantages and disadvantages to ointments?

Answer 9

Advantage = Inc hydration and temperature of the skin, do not contain preservatives

Disadvantage = greasy texture, difficult to wash off, not easily spreadable

Question 10

Discuss the properties of lotions

Answer 10

Liquid or semi-liquid preparations, opaque/thin/non-greasy

May contain aqueous/ ethanolic or emulsified vehicles (can dry out the skin due to alcohol content

Question 11

Where can lotions be applied?

Answer 11

Moist surfaces including = oral mucosa, hair bearing areas (scalp, armpits)

Intact skin only

Question 12

What are some advantages and disadvantages to lotions?

Answer 12

Advantage = provide cooling effect, easily applied to hair-bearing areas, spread easily/rapidly

Disadvantages = less hydrating, contain alcohol, can only be put on intact skin

Question 13

Discuss the properties of gels

Answer 13

Transparent or translucent semi-solid preparations

Liquid phase suspended within 3D polymer matrix

Question 14

Where can gels be applied?

Answer 14

Most areas of body

oily areas such as face

skin and mucous membranes

Question 15

What are some advantages and disadvantages to gels?

Answer 15

Advantage = cosmetic elegance, easy to apply/wash off, provide cooling sensation, non greasy

Disadvantage = may dry skin out once water evaporates, no occlusive effects, little hydration, perspiration can remove gel

Question 16

What are some characteristics of pastes?

Answer 16

semi-solid preparations w/ protective properties that may be used for the delivery of active ingredients

Finely powdered active ingredients combined with white paraffin or liquid paraffin, or non-greasy base (glycerol, soaps, emulsifying waxes, ointments)

Question 17

Where can pastes be applied?

Answer 17

thick skin

Certain mucous membranes

Question 18

What are some advantages and disadvantages to pastes?

Answer 18

Advantages = drying and protective, more occlusive and absorptive, less greasy than ointments, enhanced contact time to area

Disadvantages = difficult to spread

Question 19

What are the properties of powders for skin conditions?

Answer 19

Solid preparations, mixtures of two or more powdered active ingredients (starch, talc, kaolin)

Question 20

Where can powders be applied?

Answer 20

Moist body areas

Can be applied to broken and unbroken skin

Question 21

What are some advantages and disadvantages to powders?

Answer 21

Advantages = absorbs moisture, easy to spread and apply, can be applied on unbroken skin

Disadvantages = overuse can cause powdery residues

Question 22

Discuss the characteristics of sprays

Answer 22

Suspension aerosols

Contain lubricant or dispersing agent

Capable of treating large areas

Question 23

Where can sprays be applied?

Answer 23

Where direct application is difficult or painful

Question 24

What are the advantages and disadvantages to sprays?

Answer 24

Advantage = contact-less application, cooling effect, little waste

Disadvantage = can sting or burn

Question 25

What factors influence topical treatment of skin conditions?

Answer 25

Skin damage = inc permeability

Crusting or scaling skin = reduce permeability

permeability = vary because of lipid structures of skin, skin thickness, potential occlusion

skin hydration = due to high humidity, occlusion, wet dressing –> inc systemic drug absorption

Children = higher surface area:weight ratio –> absorb higher systemic dose

Elderly = thin, fragile skin –> inc permeability

type of drug vehicle

Question 26

What are some similarities between emollients and moisturisers?

Answer 26

Both contain lipids = emulsified oils and fatty acids (replace natural oils in skin)

high lipid, low water content = heavy, greasy

low lipid, high water content = lighter, less greasy

Question 27

What ingredients do moisturisers contain that are different from emollients?

Answer 27

Humectants = add water to the stratum corneum

Emollients = soften and prevent water loss

Occlusives = form physical barrier to prevent water loss

Question 28

When should moisturisers be applied?

Answer 28

After a bath = trap water in stratum corneum –> in direction of hair growth

Wait 30 mins before/after topical steroids to apply

Question 29

How much moisturiser should be used?

Answer 29

liberally and regularly

Face = 15-30 g cream, 100mL lotion

Trunk (2wks) = 400g cream/500mL t