Pharmaceutical Dispersions

Question 1

Disperse System Outline

Answer 1

System with 2 distinct phases (dispersed phase and continuous phase) and an interface between each phase. Phases don’t want to mix. Not thermodynamically stable

Question 2

Particle Def

Answer 2

An aggregation of molecules: ranging from 2 particles to millions of molecules. Tend to be in micron to nanoparticle size range. Dissolution breaks particles into their individual molecules

Question 3

Molecules Def

Answer 3

Smallest unit of a chemical compound that retains all native properties of the compound

Question 4

Interface Outline

Answer 4

region between 2 phases. Surface free energy forms the interface (no surface free energy = no interface). Characteristics of interface determine stability of dispersion

Question 5

Molecular Dispersion Outline

Answer 5

Nano-particles. Thermodynamically stable, homogenous solution. No refraction of light

Question 6

Colloidal Dispersion Outline

Answer 6

micro/nano particles. Not thermodynamically stable. Large soluble particles/small insoluble particles. Refracts blue light

Question 7

Coarse Dispersion Outline

Answer 7

> 500 nms (nanoparticles)

Question 8

Lyophobic Colloids Outline

Answer 8

Solute is insoluble in solvent. Results in suspended/non dissolved particles. Suspensions (closer to coarse). Thermodynamically unstable due to large amount of surface free energy

Question 9

Lyophilic Colloids

Answer 9

Solute is soluble in solvent. Creates a colloidal solution. Thermodynamically stable dispersion. (non-homogenous (interfaces present) and light scattering. Different from molecular). Eg charcoal in oil (oleophilic)

Question 10

Hydrocolloids Outline

Answer 10

Gels formed by aggregation of lyophilic polymer encased in a continuous mesh phase. Thermodynamically stable if constantly hydrated

Question 11

2 Types of Gel

Answer 11

Type 1: irreversible crosslinking and type 2: reversible crosslinking

Question 12

2 characteristics at the interface

Answer 12

electrical double layers and adsorption

Question 13

Sol Meaning

Answer 13

colloidal suspensions vs coarse suspensions.

Question 14

Lyophobic Sols Outline

Answer 14

Solute is wetted but not dissolved in solvent

Question 15

Association Colloids Outline

Answer 15

aka Micelles. Solutes self associate. Thermodynamically stable. When surfactant conc increases above CMC, surfactants assemble into spgerical molecules

Question 16

Surfactant Def

Answer 16

Amphiphilic (hydrophobic and hydrophilic components)

Question 17

What happens as a result of coarse dispersion thermodynamically stable

Answer 17

Particles steele out of dispersion. Particles aggregate together. Results in 2 separate substance layers (lower energy state). Particles settle with Brownian motion

Question 18

Progression of lyophobic colloids

Answer 18

Lyophobic colloids to coarse dispersions to 2 separate layers

Question 19

How to increase the stability of coarse dispersions

Answer 19

surface free energy reduction, viscosity increasing and shaking (shear stress application)

Question 20

Course Dispersion examples

Answer 20

aerosols (solids/liquids in gas), suspensions (solid in liquids), emulsions (liquid in liquid), creams (liquid in liquid) and foam (gas in liquid)

Question 21

Brownian Motion Outline

Answer 21

Particles in dispersions moving without pattern due to collisions with other particles. Increased movement = increased kinetic energy = increased temperature

Question 22

Caking Def

Answer 22

Tight packing of particles that fell out of solution really fast. Impossible to break apart by aggregation. Patients receive no drug

Question 23

Creaming Def

Answer 23

Drug pools at top, excipient at bottom. Result in overdosing

Question 24

Suspensions relationship to sedimentation

Answer 24

Suspensions control rate of sedimentation

Question 25

Emulsions relationship to sedimentation

Answer 25

emulsions prevent creaming