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PHA 327 - Exam 2 - Suspensions 2

  1. What characteristics are ideal for suspensions (5)?
    • Pleasant taste and odor
    • Pourable and flowing in syringe
    • Resist microbial growth
    • Remains uniform after dispersion until dosed/no fast settling
    • Sediment should not form a cake
  2. What three ideal characteristics should a lotion have?
    • Spread over surface but doesn’t run off
    • Dries quickly on skin and remains as an elastic film of drug
    • Good odor and color
  3. How do particles dispersed in a suspension aquire charges?
    • Selective absorption of ions
    • Ionization of functional groups
    • A difference in the dielectric constant between the particle and its dispersion medium
  4. Selective absorption of ions, ionization of a functional group and a difference between the dielectric constant of a particle and its medium are all ways that what occurs?
    Dispersed particles acquire a charge
  5. What is the electric double layer?
    A tightly bound layer of ions and a second more diffuse layer around a charged particle in suspension
  6. A tightly bound layer of ions followed by a second more diffuse layer of ions around a particle in a suspension is called what?
    The electric double layer
  7. What is the zeta potential (electro-kinetic potential)?
    • Image Upload 2
    • The difference in potential between the surface of the tightly bound layer of ions and the electroneutral region of the suspension.
  8. The difference between the surface of the tightly bound layer of ions and the electro-neutral region of the suspension is called what?
    The Zeta potential
  9. What is the Nernst potential?
    • Image Upload 4
    • The potential difference between the surface of the solid in a suspension and the electro-neutral bulk
  10. What is the potential between the surface of the solid in a suspension and the electro-neutral bulk called?
    The Nernst potential
  11. A low Zeta potential correlates with what suspension behavior?
    Poor stability
  12. Poor stability correlates with what relative Zeta potential?
    Low Zeta potential
  13. A high Zeta potential correlates with what suspension behavior?
    Excellent stability
  14. Excellent stability correlates with what relative Zeta potential?
    High Zeta potential
  15. A Zeta potential of 0 to ±5 has what stability behavior?
    Rapid coagulation or flocculation
  16. A Zeta potential of ±10 to ±30 has what stability behavior?
    Incipient instability
  17. A Zeta potential of ±30 to ±40 has what stability behavior?
    Moderate stability
  18. A Zeta potential of ±40 to ±60 has what stability behavior?
    Good stability
  19. A Zeta potential of more than ±61has what stability behavior?
    Excellent stability
  20. What Zeta potential correlates with Excellent Stability?
    more than ±61
  21. What Zeta potential correlates with Good stability?
    ±40 to ±60
  22. What Zeta potential correlates with Moderate stability?
    ±30 to ±40
  23. What Zeta potential correlates with Incipient instability?
    ±10 to ±30
  24. What Zeta potential correlates with Rapid coagulation or flocculation?
    0 to ±5
  25. What are the units for the Zeta Potential?
    mV
  26. The ions that give a particle its charge in a disperse system are called what?
    Charge-determining particles
  27. According to Stoke’s equation, what ways can the velocity of sedimentation be reduced?
    • Image Upload 6
    • Decreasing particle size
    • Minimizing the difference in densities between the internal and external phases
    • Increasing the viscosity of the vehicle
  28. Higher viscosity of the vehicle imparts slower sedimentation and higher___________?
    Stability
  29. What are the disadvantages of increasing the viscosity of the vehicle?
    More difficult to pour and dose
Author
kyleannkelsey
ID
214987
Card Set
PHA 327 - Exam 2 - Suspensions 2
Description
PHA 327 - Exam 2 - Suspensions 2
Updated

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