suspensions 1

Question 1

suspensions

Answer 1

dispersed system where solid particles are dispersed in a liquid phase (2 PHASES)

Question 2

prefers solubility of suspensions

Answer 2

minimum solubility of suspensions in the vehicle (external phase)

bc if full solubility then it turns to solution

Question 3

types of pharmaceutical suspensions

Answer 3

1- dispersion medium
-aqueous
-oily

2-stability
-ready to use(stable)
-reconstituted powder (unstable)

3-formulation
-fluccolated or defluccolated

4-uses
- oral , parenteral (INTRAMUSCULAR/SUBCUTANEOUS) , topical ,eye drops

Question 4

why not intravenous

Answer 4

bc this can block the capillaries and cause coagulation/ clotting

intermuscular doesnt go straight to circulation

Question 5

why are suspensions needed?

Answer 5

• In the case of the drug was insoluble therefore liquid dosage form is required

-to stabilize a drug that is chemically unstable (solutions) by suspending the particles. since they can undergo hydrolysis or oxidation due to their solubility and size

-masking the taste by decreasing solubility

-use of depot injections, controlled drug delivery, increasing the time in which the drug is released and absorbed

since the drug is not injected directly into the capillaries but into the interstitial fluid and later diffuses

Question 6

benefits of suspensions

Answer 6

due to their small particle size compared to solid dosage forms, they have large surface area which aids in

-adsorption of toxins

-neutralize acidity (antacids)

Question 7

features desired in suspensions

Answer 7

-dont settle quickly (viscosity should be high enough to prevent sedimentation) and uniformly dispersed for accurate dosage measurements

-sediment produced during storage must be easily resuspended/redispersed

-uniform particle size which is constant ( to prevent crystal growth and gritty texture)

-resistant to microbial contamination

-

Question 8

what are the solutions for drugs that degrade in the presence of water?

Answer 8

-synthesize an insoluble salt derivative as a suspension

• formulate as reconstituted suspension

-formulate suspensions in oil

Question 9

other names for suspensions formulated for parenteral administration of action of the drug

Answer 9

reservoir , long acting , depot

Question 10

coagulation of suspensions is called

Answer 10

caking (compaction)

Question 11

physical stability of suspensions

Answer 11

-physically unstable bc heterogenous system

-can undergo sedimentation, particle particle interaction and caking (compaction)

Question 12

two physical stability aspects of suspensions are?

Answer 12

-particle size growth
-caking

Question 13

two phenomena affecting particle-particle interactions and caking

Answer 13

• electrical properties of dispersed particles
• the effect of distance separating the particles

Question 14

suspension is primary minimum

Answer 14

caking occurs , irreversible

high attraction btw particles

Question 15

suspensions in secondary minimum

Answer 15

particles are weakly attracted

fluccoaltion occurs which stabilizes suspension to not form caking

Question 16

why are floccules imp for suspension

Answer 16

since they can be broken down by shaking and redisperesed

this allows accurate dose measurement

Question 17

pre-formulation of suspensions

Answer 17

1-choose suitable particle size

-control particle size growth to prevent crystal growth and avoid changes in particle size distribution

2- use a specific particle size range

• to control the rate of dissolution and bioavailability
• to decrease crystal growth / to decrease different sizes

3- use stable polymorphic form of drug

-different polymorphs=different solubilities

4- prevent crystal growth

Question 18

why is large particle size bad

Answer 18

-cause gritty texture

-irritation if injected or to the eyes

-blocks hypodermic needles

Question 19

another name for crystal growth

Answer 19

ostwald ripening or coarsening

Question 20

crystal growth is caused by

Answer 20

Temperature

meta stable has more solubility than stable

smaller particles have faster dissolution than large ones

Question 21

how to control crystal growth

Answer 21

• select suitable particle size
• use viscous vehicle to retard dissolution

-select the stable crystalline form that has less solubility

metastable can be used unless it doesn’t change to stable during storage which affect solubility

• prevent temp fluctuations during storage

Question 22

controlled flucculation

Answer 22

a compromise made where viscosity is controlled so that the sedimentation rate is at a minimum preventing caking