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MPharm 2 - PH2107 > Unit 2 - Topical Formulations > Flashcards

Unit 2 - Topical Formulations Flashcards

1
Q

Where is hairy skin found?

A

Everywhere except palms of hands and soles of feet

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2
Q

What is the outer dead layer of skin called

A

Stratum corneum

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3
Q

What is the structure of the epidermis?

A

Keratinocytes
Melanocytes
Langerhans cells

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4
Q

What is the structure of the dermis?

A

Blood vessels
Sweat glands
Base of hair follicles
Sense cells

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5
Q

What is the function of the skin?

A
  • active barrier (adapts to conditions)
  • regulates body temperature
  • mediates sensation
  • expresses emotion (reddening)
  • identifies us
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6
Q

How can skin be damaged?

A
  • mechanically (cuts)
  • chemically (burns)
  • biologically (microbes)
  • radiation (UV)
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7
Q

Why might applications be put onto the skin?

A
  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
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8
Q

What are the five targets of topical delivery?

A
  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
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9
Q

What factors affect topical delivery?

A
  • skin age
  • skin delivery
  • skin region
  • skin metabolism
  • species
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10
Q

How does skin age affect drug delivery?

A

Collagen structure changes

  • thickness of layers
  • elasticity
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11
Q

How does skin condition affect drug delivery?

A

Hydration - cracked skin affects the barrier

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12
Q

How does skin region affect drug delivery?

A
  • plantar (hairless)
  • palmar (hairless)
  • scrotal
  • scalp
  • arm
  • leg
  • trunk (torso)
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13
Q

How does skin metabolism affect drug delivery?

A
  • defensive enzymes
  • flora on skin
  • oils on skin
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14
Q

How does species of skin affect drug delivery?

A

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

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15
Q

Give examples of topical formulations

A
  • topical semi-solid preparations (e.g. creams, gels, ointments, pastes)
  • lotions
  • patches
  • powders
  • microneedles
  • sprays
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16
Q

What is a topical semisolid formation?

A

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

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17
Q

What is a semi solid?

A

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

  • solids retain shape when acted upon by external stimuli
  • liquids flow indefinitely
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18
Q

What is the structure of a cream

A
  • oily phase

- aqueous phase

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19
Q

Give examples of topical semi-solid preparations

A

Ointments
Pastes
Creams
Gels

20
Q

Describe the properties of ointments

A
  • water emulsifying (e.g. wool alcohols ointment BP)
  • hydrophobic (e.g. calamine ointment BP)
  • hydrophilic (e.g. macromolecules ointment BP)
21
Q

Describe the properties of creams

A
  • hydrophobic (w/o)

- hydrophilic (o/w)

22
Q

Describe the properties of gels

A
  • hydrophobic

- hydrophilic

23
Q

Describe an ointment

A

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
24
Q

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

A
  • occlusive

- non-occlusive

25
Q

What is transepidermal water loss?

A

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

26
Q

what does occlusive mean ?

A

To close, obstruct, or prevent the passage

27
Q

What effect does an occlusive ointment have on the skin?

A

Stops water loss

Moisturises skin

28
Q

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

A

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

29
Q

Why do topical drugs get delivered to different extents?

A

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

30
Q

What are the six main types of ointment bases?

A
  • hydrocarbons
  • fats and fixed oils
  • silicones
  • absorption bases
  • emulsifying bases
  • water-soluble bases
31
Q

Describe hydrocarbons as an ointment base

A

Hard, soft and liquid paraffins

32
Q

What type of ointment base is the most widely used?

A

Hydrocarbons

33
Q

How does a hydrocarbon ointment base work?

A

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

34
Q

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

A
  • relatively inert

- few incompatabilities

35
Q

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

A

Soft paraffin is often mixed with liquid and hard paraffin

36
Q

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

A

They absorb flammable bases which can then catch fire easily

37
Q

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

A

Vegetable origin

  • peanut (arachis)
  • sesame
  • olive
  • cotton seed
  • almond
38
Q

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

A
  • batch
  • growing conditions
  • country of origin
39
Q

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

A

Mixtures of saturated and unsaturated fats

40
Q

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

A
  • exposure to air
  • exposure to light
  • increased temperature (rancidity)
41
Q

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

A

Metallic impurities

- metal ions in source or excipients used

42
Q

Describe fats and fixed oils as an ointment base

A

Occlusive and sticky

43
Q

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

A

Stops trans-epidermal water loss

44
Q

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

A

Allergies

  • peanut oil (arachis)
  • sesame oil
45
Q

What is the function of silicones as an ointment base?

A

Water repellent

- used in barrier creams to protect against water soluble irritants

MPharm 2 - PH2107 (26 decks)

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