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Stage 3 Case 3 > Creams > Flashcards

Creams Flashcards

1
Q

What is a cream?

A

As semi-solid emulsion. Dispersed system stabilised using a suitable emulsifier.

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2
Q

What is the consistency of creams?

A

Soft spreadable consistency

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3
Q

What is the administration of creams?

A

Topical (external) for application to skin or mucous membrane

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4
Q

O/W cream

A

Oil in water semi-solid emulsion (Hydrophilic)

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5
Q

W/O cream

A

Water in oil semi-solid emulsion (Lipophilic)

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6
Q

Hydrophilic (O/W) continuous phase

A

Water and oil dispersed as droplets in it.

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7
Q

Lipophilic (W/O) continuous phase

A

Oil and water dispersed as droplets in it.

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8
Q

Hydrophilic cream (O/W) characteristics

A
  • Non-greasy.
  • Miscible with skin secretions.
  • Water-washable.
  • Non-occlusive.
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9
Q

Lipophilic cream (W/O) characteristics

A
  • Somewhat greasy (less so than ointments).
  • Less miscible with skin secretions than O/W.
  • Less water-washable than O/W.
  • Somewhat occlusive (less so than ointments).
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10
Q

Hydrophilic cream (O/W) greasiness

A

Non-greasy.

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11
Q

Hydrophilic cream (O/W) miscibility with skin

A

Miscible with skin secretions.

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12
Q

Hydrophilic cream (O/W) water washability

A

Water-washable.

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13
Q

Hydrophilic cream (O/W) occlusive?

A

Non-occlusive. (does form a barrier to prevent moisture loss)

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14
Q

Lipophilic cream (W/O) greasiness

A

Somewhat greasy (less so than ointments).

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15
Q

Lipophilic cream (W/O) miscibility with skin

A

Less miscible with skin secretions than O/W

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16
Q

Lipophilic cream (W/O) water washability

A

Less water-washable than O/W

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17
Q

Lipophilic cream (W/O) occlusive?

A

Somewhat occlusive (less so than ointments)

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18
Q

4 basic components of a cream

A

– Drug.

– Continuous phase.

– Dispersed phase.

– Emulsifier—stabilise emulsion.

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19
Q

Purpose of emulsifier in liquid emulsions

A

Allows the droplets to remains as droplets in the cream. Required as the two phases are immiscible.

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20
Q

What other 6 comportment can a cream contain?

A
  • Co-solvent
  • Thickener
  • Preservative
  • Penetration enhancer
  • pH regulator
  • Antioxidant
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21
Q

Purpose of a co-solvent in a cream

A

Enhances solubility.

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22
Q

Purpose of a thickener in a cream

A

Enhances viscosity/stability/release profile.

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23
Q

Purpose of a preservative in a cream

A

Prevents microbial spoilage.

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24
Q

Purpose of a preparation enhancer in a cream

A

Enhances drug penetration.

25
Q

Purpose of a pH regulator in a cream

A

Adjusts pH, reduces irritation.

26
Q

Purpose of an antioxidant in a cream

A

Prevents oxidative degradation.

27
Q

How to prepare a cream (5)

A
  1. Dissolve lipophilic ingredients (molten) in oily phase at minimum temperature necessary.
  2. Dissolve hydrophilic ingredients in aqueous phase, heat to same temperature as oily phase.
  3. Mix both phases at same temperature
  4. Stri until emulsion (cream) is formed
  5. Incorporate solids by titration
28
Q

To ensure sufficient dose and even dispersion of ingredients

A
  • Good solubility in either phase.

- Or, incorporate solids homogenously by trituration.

29
Q

To ensure stable emulsion

A

– Choice of suitable emulsifiers, commonly amphiphilic surfactants.

– Hydrophile-lipophile balance (HLB) and Bancroft’s rule.

30
Q

Purpose of Calamine 4% w/w in Aqueous calamine cream BP

A

Active ingredient

31
Q

Purpose of Zinc oxide 3% w/w in Aqueous calamine cream BP

A

Active ingredient

32
Q

Purpose of Purified water in Aqueous calamine cream BP

A

Aqueous phase

33
Q

Purpose of Cetomacrogol emulsifying wax in Aqueous calamine cream BP

A

Oily phase

34
Q

Purpose of Glyceryl monostearate in Aqueous calamine cream BP

A

Emulsifier

35
Q

Purpose of Liquid paraffin Aqueous in calamine cream BP

A

Oily phase

36
Q

Purpose of Phenoxyethanol in Aqueous calamine cream BP

A

Preservative

37
Q

What the way you can check the suitability of an emulsifier?

A

Bancroft’s rule (HLB value)

38
Q

Bancroft’s rule

A

High HLB emulsifier, O/W emulsion.

Low HLB emulsifier, W/O emulsion.

39
Q

Hydrophilic emulsifier HLB value

A

High HLB (>10).

40
Q

Lipophilic emulsifier HLB value

A

Low HLB (<10).

41
Q

HLB matching

A

– Different oils have different HLB requirements for O/W and W/O emulsions.

– Use emulfisier blends if necessary.

– Most stable emulsions contain more than single emulsifier.

42
Q

HLB

A

Hydrophilic-lipophilic balance on a scale of 0-20.

43
Q

How to calc HLB values requirements

A

Req HLB x Mass % (added together)

44
Q

How to calc blend of emulsifiers using HLB values

A

HLB1x + HLB2(1-x)=Req HLB

45
Q

What is an Emulgel?

A

Emulsion (O/W or W/O) + gel

Gel is the continuous phase

46
Q

Emulgel advantages (6)

A

– Incorporation of poorly water soluble drugs in a water-based formulation.

– Non-greasy.

– Good patient acceptability.

– Dual release control mechanisms.

– Viscous continuous phase enhances emulsion stability.

– Thixotropy enhances spreadability.

47
Q

Emulgel disadvantages

A

Entrapment of air bubbles

48
Q

Polymeric emulsifier (Pemulen)

A

Cross-linked copolymers:

– Alkyl acrylate (hydrophobic)

– Acrylic acid (hydrophilic)

49
Q

Alkyl acrylate (hydrophobic) in polymeric emulsifier

A

integrates in core of oil droplets.

50
Q

Acrylic acid (hydrophilic) in polymeric emulsifier

A

forms viscous gel in aqueous continuous phase, de-swells on contact with skin electrolytes to cause rapid release of oil phase.

51
Q

Polymeric emulsifier (Pemulen) emulsion type

A

O/W emulsions

52
Q

Polymeric emulsifier (Pemulen) mucoadhesive?

A

Helps retain the formulation on mucus membranes

53
Q

Purpose of Carbomer in double base gel

A

Gel (Liquid phase)

54
Q

Purpose of Glycerol in double base gel

A

Hydroxy donors (help carbomer swell)

55
Q

Purpose of Phenoxyethanol in double base gel

A

Antimicrobial preservative

56
Q

Purpose of Purified water in double base gel

A

What gel is in

57
Q

Purpose of Sorbitan laurate in double base gel

A

Emulsifier

58
Q

Purpose of Trolamine laurate in double base gel

A

Hydroxy donors (help carbomer swell)

Stage 3 Case 3 (8 decks)

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