Emulsions

Question 1

What are emulsions?

Answer 1

Composed of 2 phases consisting of fine droplets of oil in water or water in oil

Question 2

What combination are oral emulsions usually?

Answer 2

Oil in Water

Question 3

Oil in Water emulsions

Answer 3

Oil is the disperse phase
Water is the continuous phase

Question 4

Water in Oil

Answer 4

Water is the disperse phase
Oil is the continuous phase

Question 5

What dosage forms is oil in water used for?

Answer 5

Oral and IV medicines

Question 6

What dosage forms is water in oil used for?

Answer 6

External and IM medicines

Question 7

What is a microemulsion?

Answer 7

Dispersed droplets are 1nm to 1μm in size
Homogeneous, transparent systems that are thermodynamically stable

Question 8

What are microemulsions also known as?

Answer 8

Colloidal emulsions

Question 9

What are 2 tests that can be done to differentiate between oil and water?

Answer 9

Water soluble food dye - disperse quickly if water is the continuous phase
Conductivity testing - oil does not conduct so no conduction - oil in water

Question 10

What does interfacial tension depend on?

Answer 10

The surface area in contact with the other phase

Question 11

What are emulsifying agents used for?

Answer 11

Lowering interfacial tension

Question 12

What type of emulsion is used for oral consumption?

Answer 12

Oil in Water

Question 13

What are commonly used as emulsifying agents in oral preparations?

Answer 13

Synthetic non-ionic surfactants, hydrocolloids and gelatines

Question 14

What type of emulsion is used for IV?

Answer 14

Oil in water

Question 15

An example of an IV emulsion

Answer 15

Total Parenteral Nurtition TPN

Question 16

Why is oil used as the disperse phase in TPN?

Answer 16

Oil will solubilise lipophilic vitamins and proteins

Question 17

Examples of oils used in TPN

Answer 17

Cottonseed, olive and safflower as they have a high calorific value

Question 18

What type of emulsion are lotions and creams?

Answer 18

Oil in water

Question 19

What type of emulsions are ointments?

Answer 19

Water in oil

Question 20

What is HLB a characteristic of?

Answer 20

Relative polarity

Question 21

What does a higher HLB indicate?

Answer 21

More hydrophilic emulsifying agent

Question 22

What are spans?

Answer 22

Soribtan esters

Question 23

Why do spans have a low HLB?

Answer 23

They are lipophilic

Question 24

What are tweens?

Answer 24

Poly(oxyethylene) derivatives of span

Question 25

What is the HLB value of tweens?

Answer 25

High as they are hydrophilic

Question 26

What is the HLB range of Spans?

Answer 26

1.8

Question 27

What is the HLB range of Tweens?

Answer 27

9.6

Question 28

How is the Required HLB calculated?

Answer 28

Based of the weight fraction of each oil component

Question 29

What are the properties of an ideal emulsion?

Answer 29

Globules of disperse phase retain their inital character Globules remain evenly distributed Emulsions do not support microbial growth

Question 30

Properties of an ideal emulsifying agent

Answer 30

Produces a stable emulsion at low temperatures No creaming or cracking No flocculation or deflocculation No phase inversion Odourless and tasteless

Question 31

How is the degree of creaming calculated?

Answer 31

Degree of creaming = volume of cream/total volume

Question 32

How is microscopic evaluation done?

Answer 32

Measure the globule size using an optical microscope or laser diffraction

Question 33

How is accelerated stability done?

Answer 33

Storage at adverse temperatures Centrifugation at 200-300rpm to increase sedimentation

Question 34

What kind of flow do most emulsions exhibit?

Answer 34

Non-Newtonian Flow - usually pseudoplastic

Question 35

What happens to the viscosity of the disperse phase as the particle size decreases?

Answer 35

Viscocity increases

Question 36

What is viscosity proportional to?

Answer 36

The concentration of emulsifying agent

Question 37

What are desirable properties of preservatives in emulsions?

Answer 37

Low Toxicity Wide anti-bacterial spectrum Bactericidal Activity not affected by emulsion ingredients Suitable partitioning

Question 38

What kind of preservatives are effective in emulsions?

Answer 38

Free and unbound