Lab Final - Suspensions

  1. disperse system definition
    two phased liquid prep made of undissolved drug/immiscible liquid (dispersed phase) distributed in a vehicle (dispersion medium)
  2. suspension definition
    disperse system in which a finely divided solid is dispersed in a continuous phase of solid, liquid, or gas
  3. particle size of single vs two phase
    • single phase: <1 nm
    • two phase: 10-50 μm
  4. what is a suspension made of?
    • dispersed particle (drug)
    • liquid medium
    • excipients
  5. suspension excipients
    • wetting agents
    • flocculating agent
    • viscosity enhancer/suspending agent
    • preservative (benzoic acid, sodium benzoate)
    • flavoring agent
  6. when are wetting agents used in suspensions?
    when the dispersed phase isn't easily penetrated by the vehicle (clumps or float)
  7. what do wetting agents in suspensions do?
    displace the air making the powder more penetrable by dispersion medium
  8. examples of suspension wetting agents
    • alcohol
    • glycerin
    • other hygroscopic liquids
  9. what happens in unstable suspensions
    • dispersed particles form aggregates
    • aggregates settle by dispersion
    • cakes form that are difficult to resuspend
  10. stokes law gives you what?
    the settling velocity of a smooth, rigid sphere in a viscous fluid - sedimentation rate
  11. what factors affect the sedimentation rate?
    • size of the particle (proportional to)
    • density diff between the particle and liquid (proportional to)
    • viscosity of the liquid (inversely proportional)
  12. when is the sedimentation rate zero?
    when the density of the particle is equal to the density of the liquid
  13. what do flocculating agents do?
    • enhance particle dispersability
    • negate the surface charge on the suspended particles
    • allows the formation of loose networks of particles called "floccs/floccules" - easily re-dispersed by shaking
  14. examples of flocculating agents
    • clay
    • surfactants
  15. types of viscosity enhancers/suspending agents
    • natural hydrocolloids
    • semisynthetic hydrocolloids
    • synthetic hydrocolloids
    • clays
  16. examples of natural hydrocolloids used as a viscosity enhancer/suspending agent
    • acacia
    • tragacanth
    • alginic acid
    • carrageenana
    • locust bean gum
    • guar gum
    • gelatin
  17. examples of semisynthetic hydrocolloids used as a viscosity enhancer/suspending agent
    • methylcellulose
    • sodium carboxymethylcellulose
  18. example of synthetic hydrocolloid used as a viscosity enhancer/suspending agent
  19. examples of clay used as viscosity enhancer/suspending agent
    • bentonite
    • veegum
  20. what is a prednisolone/sulfacetamide suspension for?
    treating inflammation of eyes and eyelids when infection or risk of infection is present

    anitbacterial and corticosteroid combo
Card Set
Lab Final - Suspensions
Lab Final