Card Set Information
ex. polysorbate 20
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,
, cetyl ROH, acacia, Glyceryl monostearate
Aid in attaining intimate contact between solid particles and a liquid
ex. Polysorbate, Sodium lauryl sulfate, Benzalkonium chloride
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
Used to increase thickness or hardness of a preparation
Used to soften the skin and make it more pliable
ex. Mineral Oil, petrolatum, lanolin
Used to provide an acidic medium for product stability
– also used as an antioxidant, buffering agent, chelating agent, and flavor enhancer
Used to resist change in pH upon dilution or addition of acidic or alkali agents
ex. Potassium phosphate, monobasic, and sodium acetate
Inert filler to create desired bulk and flow properties
Also aids in compression characteristics of tablets and capsules
ex. lactose, mannitol, sorbitol, starch
Used in liquid and semisolid preparations to prevent growth of microorganisms
, sodium acetate, sodium benzoate, parabens, ROH
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
Scientific study of
deformation and flow properties of matter
Applied to solids, liquids and gases
Rheology describes consistency of products based on ...
viscosity and elasticity
Measure of resistance to flow or thickness
Measure of stretchiness or structure
Predominantly solid feature
Higher the viscosity...
greater the resistance of the material to flow
Phenomenon observed in materials exhibiting both elastic behavior and viscous flow
i.e. polymer gel, gelatin
Rheology plays an important role in...
dispensing and formulation of various dosage forms including emulsions, suspensions, creams, lotions and tablet coatings
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
Thixotropic materials become more fluid with increasing time of applied force (stirring, pumping, shaking)
Thixotropic systems usually contain...
asymmetric particles that provide a loose three dimensional structure via numerous points of contact throughout the sample.
Describe Thixotropy at rest and when shear is applied:
: structure provides a degree of rigidity on the system that resembles a gel
: the structure begins to breakdown as points of contact are disrupted and particles become aligned.
Study of deformation and flow in biological systems
Biological fluids are viscoelastic materials that are rheologically complex
What is blood?
and rheological properties of blood are influenced by many pathological conditions
How are the flow properties of blood determined?
hematocrit (Hct) and plasma viscosity
Elevated Hct is associated with arteriosclerosis, angina, myocardial infarction.
Rheology of suspensions and emulsions:
Final product should be pourable or injectable
: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
Polymeric gels used in drug delivery:
Development of systems that gel in situ upon administration
Used in preparations to provide alkaline medium for product stability
Any component other than the active principle added intentionally to the medicinal formulation
Excipients contribute to...
the physiochemical properties of pharmaceuticals
Ensure the weight, consistency and volume necessary for proper dosage administration