Skin function and preparations

Question 1

Anatomy Dermis

Answer 1

Connective tissue that supports epidermis.
Thickest layer.
Contains: collagen, elastin, immune cells, blood vessels, nerves, lymphatics, and sweat glands.
Hair follicles and sebaceous glands (alopecia and acne)

Question 2

Epidermis anatomy

Answer 2

Thin layer of stratified squamous epithelial cells with 4 or 5 layers
Stratum corneum: outer layer and barier to environment - dead skin cells (result of keratinisation)
Contains: melanocytes (produce/store melanin), lymphocytes and langerhans cells (fight germs), mekel cells (connect to nerve endings- sense of touch)

Question 3

Types of topical vehicles

Answer 3

Creams, ointments, lotions, gels, pastes, paints, powders, and sprays.

Question 4

Pros/cons of cream

Answer 4

Pros: easy to spread, not as greasy as ointments, moistening and emollient properties

Cons: evaporate or absorb when rubbed in= less hydrating than ointments

Question 4

Describe creams

Answer 4

Viscous semi-solid preparations, usually emulsions
May be:
- water miscible (oil-in-water emulsions) - aqueous creams
- oil miscible (water-in-oil emulsions) - oily creams

Used to apply active ingredients for protection, therapy, or prophylaxis.
Usually opaque

Applied to flexures, genital, large areas. Suitable for dry and weepy skin conditions.

Question 5

Hypodermis (subcutaneous layer) anatomy

Answer 5

Thermal control and energy storage
Contains: adipose and connective tissue, blood vessels, and nerves
Varied thickness

Question 6

Skin function - primary

Answer 6

Primary function- protective barrier to environment
- prevent loss of bodily fluids, prevent entry of foreign bodies, contain body structures and organs

Question 7

Skin pH

Answer 7

Aprrox 4.5-5.5 (acid mantle)
Due to fatty acids, amino acids, lactic acids, resident microflora (protection).

Question 8

Other skin functions

Answer 8

Regulate temperature
Vitamin D synthesis
Protect UV, sense
Blood reservoir
Excrete unwanted substances in sweat

Question 9

Influencing factors on skin

Answer 9

Age
Immunological status
Underlying disease status
Medication - isoretinoin/drying

Question 10

Describe ointments

Answer 10

Semi-solid preparations, solutions or dispersions
Hydrophillic greasy base (white soft paraffin) to form occlusive layer (prevent loss of heat and water)
Greasy= limi patient compliance, not appealing
Enhance absorption of some drugs - improved contact time w/ skin

Apply to areas free of hair (palms and soles) or short hair, dry skin.

Question 11

Pros/cons of ointments

Answer 11

Pros: Increase hydration and temperature of skin, do not contain preservatives
Cons: greasy, difficult to wash off, not easily spread

Question 12

Describe lotions

Answer 12

Liquid or semi-liquid preparation
Opaque, thin, and non-greasy
May have aqueous, ethanolic, or emulsified vehicles w/ antiseptic, analgesic, soothing, or protective properties
Produce cooling effect from evaporation of water from skin, may dry out to form a film

Apply on intact skin only, oral mucosa, hairy areas (scalp, armpits)

Question 13

Pros/cons of lotions

Answer 13

Pros: cooling effect, easily applied on hairy areas, spread easily and rapidly

Cons: less hydrating than ointments and creams

Question 14

Describe gels

Answer 14

Transparent or transulent semi-solid preparations
Apply to skin and mucous membranes
Liquid phase suspended in 3D polymer matrix (drug dissolved in matrix)
Produce cooling effect from evaporation of water -may dry out to form residual film

Question 15

Gels pros/cons

Answer 15

Pros: cosmetic elegance, easy to apply and wash off, cooling, non-greasy
Cons: no occlusive, little hydration, perspiration can remove

Question 16

Describe pastes

Answer 16

Semi-solid preparations w/ protective properties that may be used for delivery of active ingredient
Fine powder w/ soft paraffin or w/ non-greasy base consisting of glycerol, mucilages, soaps, emulsifying waxes and ointments

Apply to thick skin or mucous membranes

Question 17

Pastes pros/cons

Answer 17

Pros: drying and protective, more occlusive and absorptive, less greasy
Cons: Difficult to spread (enhance contact time to area)

Question 18

Describe powder

Answer 18

Solid preparations mixtures w/ 2+ powdered active ingredients
Starch, talc, or kaolin
Apply to broken/unbroken skin on most body areas

Question 19

Powders pros/cons

Answer 19

Pros: absorb moisture, easy to spread and apply
Cons: overuse can cause powdery residue

Question 20

Describe sprays

Answer 20

Formulated in suspension aerosols
Normally contain a lubricant or dispersing agent
Capable of treating large areas

Apply to direct area that is fainful

Question 21

Sprays pros/cons

Answer 21

Pros: application w/out touching skin, have a cooling effect, little waste
Cons: cause stinging and burning on application

Question 22

Factors influencing treatment of skin conditions

Answer 22

Skin damage (burns/eczema) increases permeability
Skin damage (psoriasis) reduces permeability

Permeability varies at different lipid structures (facial is more permeable), skin folds are more, palms and soles resistant

Skin hydration increased from humidity, occlusion, or dressings - increase systemic drug absorption

Children have a higher surface area (weight ratio absorbs higher systemic dose) - preterm neonates have less effective stratum corneum

Old people w/ thin/fragile skin have increased skin permeability

Question 23

Emollients vs moisturisers

Answer 23

Emollients - soften (prevent water loss)
Both have lipids (replace natural oils)
High lipid, low water = heavy, greasy

Question 24

Moisturiser ingredients

Answer 24

Humectants - add water to stratum corneum
Emollients - soften and prevent water loss
Occlusives - form physical barrier to prevent water loss