Dermal Formulations Flashcards

1
Q

What are the properties of ointments? What are the bases?

A

semi-solid

  • usually occlusive = retain moisture
  • more oily than creams

may contain active ingredients for local delivery or for emollients and/or protective roles

hydrophobic
- water free, low polarity
emulsifying
- contain o/w emulsions, anhydrous

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2
Q

What are pastes? What are the bases?

A

semi-solid
- up to 60% w/w dry solids

do not dissolve in aqueous or organic systems 
used to absorb exudates 
- fluid filtered from circulatory system
highly occlusive 
photo-protective
- protects from light

bases can be

  • hydrocarbons
  • fats
  • aqueous gel bases = less commonly used
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3
Q

What are creams?

A

semi-solid

  • emulsions = more fluid than ointments or paste due to high water content (above 50%)
  • external application

oil in water emulsions

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4
Q

What are the advantages of creams?

A

rapidly absorbed
leaves mo residues
lubricating yet pleasant feel

easily dispersed from containers

have greatest patient acceptability/compliance

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5
Q

What are the disadvantages of creams?

A

watery bases require preservatives to prevent microbial growth

may require pH buffer due to high water content

may need an anti-oxidant

formulation is more complex

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6
Q

What are waxes?

A

esters of an alcohol and carboxylic acid
- both have long alkyl chains

hydrophobic malleable solids of low melting points and low viscosities when liquefied

often are blended with true waxes

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7
Q

What are lotions?

A

external application to the skin

  • should only be applied to intact skin
  • excipients may cause damage to granulating tissues in wounds or systemic toxicity

have continuous aqueous phase
can be solutions, emulsions, suspensions

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8
Q

What are gels?

A

viscous semi-solid
- contain a gelling agent

usually aqueous
- can contain polar or non-polar solvents

thickening agent provides a scaffold to provide structure to the gel

gels can dry the skin
- especially if alcohol based

gels evaporate quickly

  • leaves drug in contact with the epidermis
  • evaporation of solvent can cause a cooling effect
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9
Q

What are powders?

A

solids

  • rarely contain any potent drug substance
  • may act as lubricants

adsorption is one of the most common purposes

  • can adsorb sweat or other exudates
  • talc, starch

highly inefficient delivery into the skin
powders are very simple, cheap, and stable medications

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