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Pharmaceutics 18-20
| Question | Answer | ||
|---|---|---|---|
| Dispersion types (Liquid) | In solid: cheese Solid Emulsion | In liquid: Milk Emulsion | In: gas: Fog, cloud Liquid aerosol |
| Dispersion types (Gas) | In solid: Marshmallow Solid foam | In liquid:Whipped Cream Foam | N/A |
| Colloidal dispersions | Micelles, Liposome, microemulsion, nano/microparticle, nano crystal, biopharmaceuticals | ||
| Coarse dispersions | Suspensions,emulsions, foam, some aerosol | ||
| Suspension | insoluble particles dispersed in liquid medium | Antibiotics, Antacids, radiopague, topical | |
| Advantages of suspensions | better chemical stability than solution, increased delivery rate than solid, allows liquid dosing of unpalitability | ||
| Disadvantages of suspensions | don't really uniformly disperse, agglomerate(aggregate to cluster), particles settle, cake up | Dosage accuracy problems, homogeneity problems, stability problems, compliance problems | |
| Increased surface area | Increased interfacial energy, not thermo stable | ||
| Homogeneity | dose consistency and evenness | ||
| Viscosity | pour readily, spread easily on skin or easily go through a syringe | ||
| Settlement | Should settle slowly and easily reversable | ||
| Particle size | Should remain constant | ||
| Electric Properties of Interfaces | Particles dispersed in liquids may become charged | ||
| Electric Double Layers | 1st: tightly bound layer 2nd: Diffuse | ||
| Tightly bound layer | dense layer of counter ions strongly attached to the surface (rigid layer) | ||
| Diffuse layer | A diffuse layer of counter ions trying to approach the particle (shear plane) | ||
| Nernst potential | Electric potential at a solid's surface | Drops rapidly across tightly bound layer More gradually across the diffuse layer | |
| Electro-kinetic(zeta) potential | Potential located at the shear plane can be +, 0, or - | Magnitude of zeta potential has implication for the stability of dispersed system | related to ionic environment of the liquid phase |
| Dispersed System(dispersion) | Continuous media:external phase, vehicle, media Dispersed phase: internal phase, matter dispersed | ||
| Dispersion types(Solid) | In solid: pearls solid solution | In liquid: Jelly gel | In gas: Smoke Solid aerosol |
Created by:
samselsw
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