Compounding Theory

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  1. 4 components of emulsions
    • 1 & 2: mixture of water and oil
    • 3: emulsifying agent
    • 4: energy (trituration, heating, shaking, etc)
  2. O/W (oil in water) Emulsions
    water: dispersion medium, external or continuous phase

    oil: dispersed liquid, internal or discontinuous phase
  3. W/O (water in oil) Emulsion
    oil: dispersion medium, external or continuous phase

    water: dispersed liquid, internal or discontinuous phase
  4. w/o emulsion are:
    • immiscible in water
    • not water washable
    • wont absorb water
    • occlusive
    • greasy
  5. o/w emulsions are:
    • miscible in water
    • water washable
    • will absorb water
    • nonocclusive
    • non-greasy
  6. emulsions are thermodynamically unstable and will seperate over time, 3 levels of instability:
    • creaming
    • coalescence
    • phase inversion
  7. creaming:
    when the dispersed droplets "fallout" and drop to the bottom

    reversible, shaking will return it to original emulsion
  8. coalescence
    breaking or cracking, the film surrounding the droplets have been destroyed

  9. phase inversion
    change in type of emulsion first intended to be formed

    often occurs after it has been made
  10. evidence of instability
    • cracking
    • crystal growth
    • shrinking due to evaporation of water
    • microbial growth/contamination
  11. methylbaraben
    preservative that can be added to an emulsion to decrease microbial growth
  12. ascorbic acid
    antioxidant that can reduce rancidification of emulsions
  13. emulsifying agent, 2 main classifications
    • chemical structure
    • mechanism of action
  14. regardless of class, all emulsifying agents must be:
    • chemically stable
    • non-reactive with other emulsion components
    • non-toxic
    • non-irritating
  15. chemical structures classes
    • synthetic (surfactants)
    • natural (hydrocolloids)
    • finely dispersed solids
    • auxillary agents
  16. mechanism of action classes
    • surface active ingredients
    • hydrophillic colloids
    • finely defined solid particals
  17. adding primary emulsion
    add active ingredient towards the end to avoid breaking the emulsion
Card Set:
Compounding Theory
2012-03-15 16:34:10

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