Disperse Systems - Dosage Forms

Question 1

Characteristics of a Solution

Answer 1

• Dissolving solute into solvent
• Has molecular dispersion & small particles
• Transparent cannot be filtered
• Doesn’t scatter light

Question 2

Disperse systems

Answer 2

• One phase (a disperse phase) is distributed throughout a second phase (a continuous phase)
• Two immiscible phases in contact

Question 3

Colloid

Answer 3

• A two-phase system of matter; a type of mixture intermediate between homogeneous mixtures and heterogeneous mixtures (size < 1 μm)

Question 4

Phase colloid

Answer 4

Small droplets or particles of one substance (the disperse phase) are dispersed in another (the continuous phase)

Question 5

Molecular colloid

Answer 5

macromolecules are dispersed in a continuous phase

Question 6

Properties of colloids

Tyndall effect

Answer 6

light scattering of particles in a fine suspension diffract the light

Question 7

Properties of colloids

Brownian motion

Answer 7

Random motion of particles suspended in a medium due to bombardment of smaller particles

Question 8

Properties of colloids

Electrophoresis

Answer 8

Migration of charged particle and surface dependant

Question 9

Properties of colloids

Absorption

Answer 9

Chemical on the surface of the second agent lead to conformational change e.g. gases absorbed on solids, absorption of surfactants polymers and proteins

Question 10

Properties of colloids

Dialysis

Answer 10

Separating molecules in solution by the difference in their rates of diffusion through a semipermeable membrane

Question 11

Thixotropy

Answer 11

Solid when at rest fluid when agitated change orientation

Question 12

Types of colloids

Answer 12

• Soap foam
  
  • Emulsion milk and mayo
  • Sol suspension toothpaste

Question 13

Lyophilic (1 phase)

Answer 13

• solvent liking
• Large organic molecules collide
• Solvated by H2O medium
• Dispersed spontaneously
• Increased viscosity forms gels
• Electrolytes generally stable but salted out by high concentration of desolvation
• Starch and gelatine
• Clear or translucent no definite boundaries between macromolecules and liquid
• Dispersed in water mobile liquid to solid
• Matted fibres
• Crystalline and amorphous regions held by van de Walls forces

Question 14

Lyophobic (phase 2)

Answer 14

• solvent hating
• Inorganic molecules and particles and insoluble
• Minimal interaction between particles in dispersion medium
• No spontaneous dispersion
• No effect on viscosity
• Low concentration of electrolytes cause it to stabilise however high is instable
• Calcium Phosphate
• Opaque not stable in single phase
• Agitate to form 3D structure sponge like network
• Flocculated small particles
  Network of elongated particles

Question 15

Sol

Answer 15

• Small solid particle in liquid medium

Question 16

Gel

Answer 16

Colloid suspension where liquid medium is viscous arrangement as a 3D solid rigid

Question 17

Gelling agent

Answer 17

• Natural gums
• Semisynthetic materials
• Synthetic material
• Humectants - prevent drying out
• Preservatives - extend the lifetime of the gel
• Water

Question 18

Foam

Answer 18

• Gas dispersed in a liquid
• Trapping gas bubbles delivered in enemas
• Foam could be by-product that’s unwanted in manufacturing hard to control volume
• Defoamer:
  = foam breakers and preventers act as small droplets foaming in the foam lamellae
  = displace surfactant
  = silicone fluids

Question 19

Emulsion

Answer 19

• Pseudo-stable liquid in liquid at least 2 immiscible liquids one dispersed thought other fine droplet oil stabilised by emulsifier agent remain dispersed

Question 20

Suspension

Answer 20

Dispersion insoluble particles > 1mcm dispersed in liquid medium aqueous settle must shake before use