suspensions

Question 1

what is a suspension

Answer 1

• coarse dispersion in which insoluble particle s
• they are heterogenous
• they feel the effects of gravity
• so they will settle at the bottom - so you can just shake it
  such calpol is a suspension of ibuprofen

Question 2

what are the difference classes of suspensions

Answer 2

• based on general classes - oral, external
• based on the proportion of solid particles
• based on electro kinetic nature of solid particle s
• based on size of solid particle s

Question 3

what’ are the advantages of

Answer 3

• you. can get poorly soluble drugs
• taste making
• improved rate of absorption
• may offer a control of release
• easy to swalllow

Question 4

what are the disadvantages

Answer 4

• physically unstable - aggregation - where particles stick together, or sedimentation
• uniform and accurate dose can not be achieved unless suspensions are packeaged in unit dosage forms
• difficult to formulate

Question 5

what is the ideal suspension

Answer 5

• suspended particles should not settle rapidly and must be easily resuspeneded - so controlled flocculation
• it should be say to pour yet not watery and not grittynes
• it should be appealing to consume
• good spring ability
• it should be physically, chemically and micro biologically stable

Question 6

what are the physical instability

Answer 6

• they have a high sa to volume ratio, however the solute of the suspension does not like being in contact with the solvent, so it doesn’t interact and does mot like being in the notions phase where dissolution is occurring (dissolution does not occur because it is a suspension) so the. solute with attempt to
• undergo sedimentation
• coagulation
• flocculation
• ostwald ripening
• adhesion of particles to containers

to make sure that they rather interact with each other rather than the solute

Question 7

how a re suspensions made

Answer 7

• milling - so grinding
• due to sedimentation the solute will settle to the bottom and from a cake - due to them all being at the bottom they can then begin to coagulate where they form bonds and this sis an irrevisible processes
• for it to go back to a spension it needs to go through m,idling agains

Question 8

how can we reduce the rate of sedimentation

Answer 8

• by looking at stokes law
• it tells us the velocity of which suspension is occurring

lower the radius - the lower the rate of sedimentation
higher the viscosity - the lower the rate of sedimentation - but you do not want to make it too thick

Question 9

what is the difference between coagulation and flocculation

Answer 9

• coagulation
  strongher interactions
• does not resuspend with shaking

flocculation
- weak energy of interactions
- resuspends with shaking

Question 10

what is the difference between flocculated and deflocculated

Answer 10

• suspensions that defloccukate when they sediment they from a cake - so flocculation is good
• the particles behave more individually
  however the sedimentation is low
  over a long time the sediment volume increases and supernatant begins

flocculated
- the particles are arranged in loose aggregates and behave as large particles
- sediments quickly
- maximum sedimentation within hours or days
- large sedimentation volume