Dosage Forms- ALL NOTES

Question 1

What is an emulsion?

Answer 1

-A pseudo-stable dispersion of at least two immiscible liquids one of which is dispersed throughout the other in the form of fine droplets - oil and water stabilised by the presence of an emulsifying agent

Question 2

What are features of emulsions?

Answer 2

-Cloudy or milky, droplet sizes are polydispersed, kiw concentration of surfactant, thermodynamically unstable but kinetically stable

Question 3

What are the types of emulsion?

Answer 3

-Normal and reverse emulsion

Question 4

What is normal emulsion?

Answer 4

-o/w emulsion, oil on inside aqueous on outside

Question 5

What is reverse emulsion?

Answer 5

-w/o emulsion, oil on outside aqueous on inside

Question 6

What is a cream ?

Answer 6

-Semi-solid emulsions of two immiscible phases stabilised by emulsifying agent

Question 7

What are o/w ‘watery’ creams?

Answer 7

-Water is the continuous medium while oil is the dispersed so doesn’t feel oily. Can deposit lipids and are readily diluted and miscible with water

Question 8

What are w/o ‘oily’ creams ?

Answer 8

-More greasy as oil is in the continuous cream, more moisturising due to oily barrier, not easily washable but more spreadable

Question 9

What determines the type of cream prepared?

Answer 9

-The type of surfactant

Question 10

What the difference between the requirements for semi-solid creams and runny emulsions ?

Answer 10

-Semi-solid creams require excess surfactant

Question 11

How do you tell if an emulsion is o/w or w/o?

Answer 11

-Dye solubility test
-Dilution
-Conductivity
-Fluorescence

Question 12

How does the dye solubility test work?

Answer 12

-Mix emulsion with a water soluble dye and observe under microscope- if droplets are coloured its w/o if system is coloured the o/w

Question 13

How does the dilution test for emulsion type work?

Answer 13

-If the emulsion is o/w and diluted with water it will remain stable but if its diluted with oil then the emulsion will break

Question 14

How does the conductivity test for emulsion type work?

Answer 14

-Electric current passed through electrodes, if passed its o/w if not its w/o

Question 15

How does the fluorescence test for emulsion type work?

Answer 15

-Based on fluorescence of oils under ultraviolet light under a microscope -if whole fluid fluorescent then w/o if spotty its o/w

Question 16

What is a micro emulsion?

Answer 16

-droplet size is 0.01-0.1 micrometers in diameter

Question 17

What does HLB mean?

Answer 17

-Hydrophile-lipophile balance

Question 18

How do you use HLB?

Answer 18

-Match the HLB of surfactants to the HLB of the oil phase

Question 19

What does higher HLB mean?

Answer 19

-Hydrophilic surfactants that act as solubilising agents

Question 20

What does a lower HLB mean?

Answer 20

-Lipophilic surfactants that act as w/o emulsifiers

Question 21

What HLB makes the most stable emulsion?

Answer 21

-Mix of surfactants with high and low HLB

Question 22

How is a oral syrup made sugar free while still providing equivalent sweetness viscosity and preservation?

Answer 22

-Artificial sweeteners, non-gycogenetic viscosity modifiers, preservatives

Question 23

What is an example of artificial sweetener?

Answer 23

-Aspartame

Question 24

What is an example of a non-glycogenetic viscosity modifier ?

Answer 24

-Methylcellulose, hydroxyethlcellulose

Question 25

What is an example of a preservative ?

Answer 25

-Sodium benzoate, benzoic acid

Question 26

What is an elixir ?

Answer 26

-Hydroalcoholic solution for oral use

Question 27

Why aren’t elixirs used more?

Answer 27

-problem with alcohol content in paediatric formulations and adults who wish to avoid alcohol

Question 28

What are the typical components of oral elixirs?

Answer 28

-Purified water, alcohol, poll co-solvents, sweetening agents, flavours and colours

Question 29

What is a linctus?

Answer 29

-Viscous preparations that contain the therapeutic agent dissolved in a vehicle made of a high percentage of sucrose

Question 30

What are linctuses used for?

Answer 30

-Mainly treatment of cough due to soothing actions on inflamed mucus membranes

Question 31

What is an oral syrup?

Answer 31

• A highly concentrated, aqueous solution of sugar or sugar substitute

Question 32

What is a suspension?

Answer 32

-Course dispersion in which insoluble particles generally less than 1 micrometer are dispersed within a liquid medium which is usually aqueous

Question 33

What should have a proper suspension have?

Answer 33

-Homogenous during dosing, easy to re-suspend , proper viscosity, particles should be small and uniform

Question 34

What does the r value mean in sedimentation?

Answer 34

-Compares the sedimentation layer volume Vs to total suspension volume Vt

Question 35

What does h infinity mean?

Answer 35

-Height of sedimented layer

Question 36

What are types of flocculating agents?

Answer 36

-Electolytes, surfactants, polymers

Question 37

What do flocculating agents do?

Answer 37

-Prevent caking in a suspension

Question 38

What are features of flocculated systems?

Answer 38

-Particles are aggregated, fast sedimentation, ‘fluffy sedimentation’ , large sedimentation volume

Question 39

What are features of a deflocculated system?

Answer 39

-Particles remain as discrete units, slower sedimentation, compact sediment, small sedimentation volume

Question 40

How can you control flocculation?

Answer 40

-Particle size, use of electrolytes to control electrostatic repulsion, addition of flocculating agents