Suspension

Question 1

Suspension is good for drugs that are insoluble or poorly soluble

Answer 1

Eg. Prednisolone, gutt neomycin,gutt hydrocortisone.

Question 2

Oral suspension

Answer 2

Must contain suitable flavouring agents.
Good for drugs with unpleasant taste. Eg. Para and chloramphenicol palmitate

Question 3

Classification of sus.according to nature of dispersed phase and method of preparation.

Answer 3

1. Diffusible solides
2. Indiffusible solids
3. Poor wettable solids
4. Precipitate forming liquids
5. Products of chemical reactions

Question 4

Diffusible solids

Answer 4

Insoluble in water but easily wettable.
Usually, they remain suspended for long

Question 5

Diffusible solids

Answer 5

Examples; magnesium trisilicate mixture , light kaolin.

Question 6

Indiffusible solids

Answer 6

Sediment too rapidly
Eg. Sulphadimidine and chalk

Question 7

Flocculated suspension

Answer 7

Usually non elegant.
Most used form of pharmaceutical product

Question 8

Flocculating agents

Answer 8

1. Neutral electrolyte like NaCl, KCl
2. Surfactants
3. Polymeric flocculating agents
4. Sulphate, citrate, phosphate salts

Question 9

Synthetic suspending agents

Answer 9

1. Carboxypolymethylene
2. Colloidal silicon dioxide

Question 10

Aerosol

Answer 10

For thickening non-aqueous suspension

Question 11

Suspending agents

Answer 11

1. Impart viscosity
2. Form film around particle and decrease inter- particle attraction

Question 12

Formulation of suspension

Answer 12

1. Size reduction of particles
2. The addition of suspending agents to increase viscosity .
3. Use of a wetting agent/surfactants

Question 13

Conclusions of Stokes

Answer 13

1. Rate of fall of larger particles > smaller particles
2. The greater the difference in density between dispersed phase particles and the continuous phase, the greater the rate of sedimentation

Question 14

Stokes conclusion

Answer 14

1. Increasing the viscosity of dispersing medium will reduce sedimentation rate

Question 15

Advantages of high viscosity

Answer 15

1. High viscosity inhibits crystal growth
2. High viscosity promotes stability

Question 16

Disadvantages of High viscosity

Answer 16

1. Affects re-dispersibility
2. Regards absorption of drug
3. Creates handling problems during manufacturing.

Question 17

Wetting agents

Answer 17

Non- ionic surfactants are normally used as wetting agents in pharmaceutical suspension

Question 18

Ionic surfactants

Answer 18

They are not generally used because they are not compatible with many adjuvants;hence, cause a change in pH.

Question 19

Surfactants

Answer 19

They have foam forming tendencies and are bitter in taste

Question 20

Polysorbate 80

Answer 20

Widely used surfactant

Question 21

Advantages of polysorbate 80

Answer 21

1. Non- toxic
2. Non-ironic so no change in ph occurs
3. Less foaming tendencies

Question 22

Polysorbate 80

Answer 22

Should be used at a concentration less than 0.5%.

Question 23

Solvents for suspension

Answer 23

Alcohol, polyethene glycol, polypropylene glycol

Question 24

Co-solvents

Answer 24

Glycerol,propylene glycol, sorbitol

Question 25

Formulation of suspension

Answer 25

1. Add wetting agents before forming a paste 2. If syrup or glycerol are in the formular, use them to form paste instead

Question 26

Formulation of suspension

Answer 26

If soluble solids are being used, dissolve them in the vehicle before or after making the paste.

Question 27

Formulation of suspension

Answer 27

Add volatile subs and flavouring agents last