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daynuhmay
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viscosity units of measure
Poise
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solid particles dispersed in a liquid phase in which the particles are not soluble
suspension
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liquid phase dispersed in liquid phase
emulsion
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size of dispersed droplets in this dispersed system has droplets/particles 1-500nm (SMALL)
colloids
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variables affecting sedimentation rate (Stoke's Law) (3)
- particle size
- particle-medium density difference
- viscosity of the medium
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2 examples of suspending agents
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2 examples of preservatives
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most desirable loose particle aggregates in suspensions; promoted by manipulating particle CHARGE
flocs/floccules
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third phase often required to promote dispersion of a liquid in another liquid & stabilization
emulsifier
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mechanism of stabilization by an emulsifier
reduce interfacial energy created by emulsification
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HLB Value 0-3: utility, example
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HLB Value 4-6: utility, example
- - W/O emulsifier
- - lanolin
(more lipophilic)
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HLB Value 7-18: utility, example
- wetting agent
- docusate sodium
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HLB Value 8-18: utility, example
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HLB Value 13-15: utility, example
- detergent
- alkyl benzene sulfonates
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HLB Value 10-18: utility, example
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emulsion method in which emulsifier is triturated w/ oil phase, then aqueous phase is added all at once
continental/dry gum method
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emulsion method in which emulsifier is triturated w/ water phase, then oil phase is slowly added w/ agitation
English/wet gum method
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emulsion method in which it is capped and shaken, then another phase is added
bottle method
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emulsion method in which emulsifiers are created through chemical reactions
in situ soap method
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4 types of emulsifiers
- 1) natural
- 2) semisynthetic
- 3) synthetic
- 4) fine solids
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how are colloids different from suspensions or emulsions?
- particles are extremely small (1-500nm)
- light can shine through
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solvent loving colloid
lyophilic
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solvent-hating colloids (little affinity for medium)
non-spontaneous dispersions w/ hydrophobic polymers of inorganic particles
lyophobic
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2 advantages of colloids
- thermodynamically stable
- not subject to separation
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formed when concentration of surfactant exceeds critical micelle concentration (used to enhance solubility of hydrophobic drugs)
micelles
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phospholipid aggregates dispersed in water; can enhance drug absorption due to similarity to cell membrane
liposomes
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