1. Surfactants:
    • Emulsifying agents
    • Wetting agents
    • ex. polysorbate 20
  2. Emulsifying agents
    • To promote and maintain dispersion of finely subdivided particles of liquid in a vehicle in which it is immiscible (oil and water)
    • ex. Sodium lauryl sulfate, lanolin, cetyl ROH, acacia, Glyceryl monostearate
  3. Wetting agents
    • Aid in attaining intimate contact between solid particles and a liquid
    • ex. Polysorbate, Sodium lauryl sulfate, Benzalkonium chloride
  4. Levigating Agents
    • Liquid used as an intervening agent to reduce the particle size of a powder by grinding (usually in a mortar)- makes paste usually
    • Mineral oil, glycerin, propylene glycol
  5. Stiffening Agents
    • Used to increase thickness or hardness of a preparation
    • (i.e. ointments)
    • ex. Ceresin, Stearyl alcohol
  6. Emollients
    • Used to soften the skin and make it more pliable
    • ex. Mineral Oil, petrolatum, lanolin
  7. Acidifying Agent
    • Used to provide an acidic medium for product stability
    • ex. Citric acid – also used as an antioxidant, buffering agent, chelating agent, and flavor enhancer
  8. Buffering agents:
    • Used to resist change in pH upon dilution or addition of acidic or alkali agents
    • ex. Potassium phosphate, monobasic, and sodium acetate
  9. Diluent
    • Inert filler to create desired bulk and flow properties
    • Also aids in compression characteristics of tablets and capsules
    • ex. lactose, mannitol, sorbitol, starch
  10. Preservatives
    • Used in liquid and semisolid preparations to prevent growth of microorganisms
    • ex. Imidurea, sodium acetate, sodium benzoate, parabens, ROH
  11. Viscosity-Increasing Agents
    • Used to render preparations more resistant to flow
    • • In suspensions to deter sedimentation
    • • In ophthalmic solutions to increase contact time
    • • To thicken topical creams
    • ex. Carbomer – gelling agent
  12. Rheology:
    • —Scientific study of deformation and flow properties of matter
    • Applied to solids, liquids and gases
  13. Rheology describes consistency of products based on ...
    viscosity and elasticity
  14. Viscosity:
    Measure of resistance to flow or thickness
  15. Elasticity:
    • Measure of stretchiness or structure
    • Predominantly solid feature
  16. Higher the viscosity...
    greater the resistance of the material to flow
  17. Viscoelasticity:
    • Phenomenon observed in materials exhibiting both elastic behavior and viscous flow
    • i.e. polymer gel, gelatin
  18. Rheology plays an important role in...
    dispensing and formulation of various dosage forms including emulsions, suspensions, creams, lotions and tablet coatings
  19. —Rheology helps us understand
    • Passage through the orifices, including pouring, packaging in bottles
    • Passage through hypodermic needles.
    • Removal from jars and extrusion from tubes
    • Spreading and adherence to the skin
    • Capacity of solids to mix with miscible liquids
    • Release of drug from the base
  20. Thixotropy
    • Thixotropic materials become more fluid with increasing time of applied force (stirring, pumping, shaking)
    • Often reversible
  21. Thixotropic systems usually contain...
    asymmetric particles that provide a loose three dimensional structure via numerous points of contact throughout the sample.
  22. Describe Thixotropy at rest and when shear is applied:
    • Rest: structure provides a degree of rigidity on the system that resembles a gel
    • Shear applied: the structure begins to breakdown as points of contact are disrupted and particles become aligned.
  23. Biorheology:
    • Study of deformation and flow in biological systems
    • Biological fluids are viscoelastic materials that are rheologically complex
  24. What is blood?
    is a non-Newtonian fluid and rheological properties of blood are influenced by many pathological conditions
  25. How are the flow properties of blood determined?
    • by hematocrit (Hct) and plasma viscosity.
    • Elevated Hct is associated with arteriosclerosis, angina, myocardial infarction.
  26. Rheology of suspensions and emulsions:
    Final product should be pourable or injectable
  27. Rheology :Removal and spreading of ointments:
    • Addition of pharmaceutical additives could change the properties of the ointment base.
    • Removal from container esp. important in case of elderly patients
  28. Rheology: Polymeric gels used in drug delivery:
    Development of systems that gel in situ upon administration
  29. Alkalizing agent:
    • Used in preparations to provide alkaline medium for product stability
    • ex. Triethanoloamine (trolamine)
  30. Excipients definition:
    Any component other than the active principle added intentionally to the medicinal formulation
  31. Excipients contribute to...
    • the physiochemical properties of pharmaceuticals
    • Ensure the weight, consistency and volume necessary for proper dosage administration
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