Unit 2 - Topical Formulations

Question 1

Where is hairy skin found?

Answer 1

Everywhere except palms of hands and soles of feet

Question 2

What is the outer dead layer of skin called

Answer 2

Stratum corneum

Question 3

What is the structure of the epidermis?

Answer 3

Keratinocytes
Melanocytes
Langerhans cells

Question 4

What is the structure of the dermis?

Answer 4

Blood vessels
Sweat glands
Base of hair follicles
Sense cells

Question 5

What is the function of the skin?

Answer 5

• active barrier (adapts to conditions)
• regulates body temperature
• mediates sensation
• expresses emotion (reddening)
• identifies us

Question 6

How can skin be damaged?

Answer 6

• mechanically (cuts)
• chemically (burns)
• biologically (microbes)
• radiation (UV)

Question 7

Why might applications be put onto the skin?

Answer 7

1. Manipulate the barrier to improve its function
   - infection
   - protection
   - emollient (moisturise)
2. Local treatment
   - anti-inflammatory
   - symptomatic relief
3. Systemic treatment
   - transdermal drug delivery (patches/topical)
   - NSAIDs
   - motion sickness
   - angina
   - hypertension

Question 8

What are the five targets of topical delivery?

Answer 8

1. Designed to stay on the surface of the skin barrier
   - protective layer
   - antibacterial/antifungal
2. Deliver to stratum corneum
   - emollient
   - hyperkeratosis
3. Deliver to skin appendages
   - hyperhidrosis
   - acne
   - antibiotics
   - transfollicular absorption
4. Deliver to epidermis/dermis (keratinocytes)
   - steroids
   - anti inflammatories
   - antipruritics (anti-itching)
   - anaesthetics
   - prior to tattoos/infections
5. Deliver to blood supply
   - systemic circulation

Question 9

What factors affect topical delivery?

Answer 9

• skin age
• skin delivery
• skin region
• skin metabolism
• species

Question 10

How does skin age affect drug delivery?

Answer 10

Collagen structure changes

• thickness of layers
• elasticity

Question 11

How does skin condition affect drug delivery?

Answer 11

Hydration - cracked skin affects the barrier

Question 12

How does skin region affect drug delivery?

Answer 12

• plantar (hairless)
• palmar (hairless)
• scrotal
• scalp
• arm
• leg
• trunk (torso)

Question 13

How does skin metabolism affect drug delivery?

Answer 13

• defensive enzymes
• flora on skin
• oils on skin

Question 14

How does species of skin affect drug delivery?

Answer 14

Pre-clinical studies needs to use skin which is very similar to human. Porcine is often used

Question 15

Give examples of topical formulations

Answer 15

• topical semi-solid preparations (e.g. creams, gels, ointments, pastes)
• lotions
• patches
• powders
• microneedles
• sprays

Question 16

What is a topical semisolid formation?

Answer 16

Semi-solid preparations for cutaneous application are intended for local or transdermal delivery of active substances or for their emollient or protective action

Question 17

What is a semi solid?

Answer 17

Formulation which possess rheology with a mixture of solid and fluid behaviour

• solids retain shape when acted upon by external stimuli
• liquids flow indefinitely

Question 18

What is the structure of a cream

Answer 18

• oily phase

- aqueous phase

Question 19

Give examples of topical semi-solid preparations

Answer 19

Ointments
Pastes
Creams
Gels

Question 20

Describe the properties of ointments

Answer 20

• water emulsifying (e.g. wool alcohols ointment BP)
• hydrophobic (e.g. calamine ointment BP)
• hydrophilic (e.g. macromolecules ointment BP)

Question 21

Describe the properties of creams

Answer 21

• hydrophobic (w/o)

- hydrophilic (o/w)

Question 22

Describe the properties of gels

Answer 22

• hydrophobic

- hydrophilic

Question 23

Describe an ointment

Answer 23

Soft, semi solid preparation

• single phase base in which solids or liquids may be dispersed
• emollient action without absorption through the skin
• protective effect against environment
• intended to adhere to the skin and mucous membranes for localised delivery

Question 24

What are the two types of ointment used in topical delivery?

Answer 24

• occlusive

- non-occlusive

Question 25

What is transepidermal water loss?

Answer 25

Loss of water through the skin naturally - not just through sweating

Question 26

what does occlusive mean ?

Answer 26

To close, obstruct, or prevent the passage

Question 27

What effect does an occlusive ointment have on the skin?

Answer 27

Stops water loss | Moisturises skin

Question 28

What effect does a non-occlusive ointment have on the skin?

Answer 28

Allows water loss - absorbs water into the ointment which passes through the ointment

Question 29

Why do topical drugs get delivered to different extents?

Answer 29

Different ointments have different properties so penetrate to different degrees through the skin

Question 30

What are the six main types of ointment bases?

Answer 30

- hydrocarbons - fats and fixed oils - silicones - absorption bases - emulsifying bases - water-soluble bases

Question 31

Describe hydrocarbons as an ointment base

Answer 31

Hard, soft and liquid paraffins

Question 32

What type of ointment base is the most widely used?

Answer 32

Hydrocarbons

Question 33

How does a hydrocarbon ointment base work?

Answer 33

Forms a greasy film on the skin (occlusive), reducing moisture loss and improving hydration (including absorption) - water comes to the skin surface which helps the water soluble drug be absorbed

Question 34

What are the advantages of using hydrocarbons as an ointment base?

Answer 34

- relatively inert | - few incompatabilities

Question 35

How can a hydrocarbon ointment base be made easily spreadable with consistent rheological properties?

Answer 35

Soft paraffin is often mixed with liquid and hard paraffin

Question 36

Why do patients need to regularly hot wash their clothes which are in contact with ointment?

Answer 36

They absorb flammable bases which can then catch fire easily

Question 37

Give some examples of fats and fixed oils as an ointment base

Answer 37

Vegetable origin - peanut (arachis) - sesame - olive - cotton seed - almond

Question 38

Why is there variation in fats and fixed oils as an ointment base?

Answer 38

- batch - growing conditions - country of origin

Question 39

What types of fats make up fats and fixed oils as an ointment base?

Answer 39

Mixtures of saturated and unsaturated fats

Question 40

How can fats and fixed oils as an ointment base decompose?

Answer 40

- exposure to air - exposure to light - increased temperature (rancidity)

Question 41

What is rancidity in fats and fixed oils as an ointment base increased by?

Answer 41

Metallic impurities | - metal ions in source or excipients used

Question 42

Describe fats and fixed oils as an ointment base

Answer 42

Occlusive and sticky

Question 43

What is the advantages of using fats and fixed oils as an occlusive ointment base?

Answer 43

Stops trans-epidermal water loss

Question 44

What are the disadvantages of using fats and fixed oils as an ointment base?

Answer 44

Allergies - peanut oil (arachis) - sesame oil

Question 45

What is the function of silicones as an ointment base?

Answer 45

Water repellent | - used in barrier creams to protect against water soluble irritants