Emulsions

Question 1

What is an emulsion?

Answer 1

A dispersed system with at least 2 immiscible liquids. One is always aqueous and one is always oleaginous.

Question 2

What is the internal phase?

Answer 2

The liquid that is finely subdivided into droplets and is dispersed through the external phase.

Question 3

What is O/W emulsions and what properties do they have?

Answer 3

Oil in water
Water is >45%= external phase
non greasy, water washable

Question 4

What is W/O emulsions and what properties do they have?

Answer 4

Water in oil
water is <45%= internal phase
greasy, occlusive, forms water repellant film

Question 5

What are the two types of multiple emulsions?

Answer 5

W/O/W= water droplets in larger oil droplets dispersed in water
O/W/O= oil droplets in larger water droplets dispersed in oil

Question 6

Pros of emulsions compared to other dosage forms?

Answer 6

-Easier to eat/ taste
- bypass dissolution= faster
- combine 2 incompatible ingredients
- better for parental administration if lipid component is necessary.

Question 7

Which emulsion is used for oral?

Answer 7

O/W= because better taste

Question 8

Which emulsion for IV?

Answer 8

O/W= because serious embolism if W/O is used

Question 9

Which emulsion for IM?

Answer 9

W/O= because of sustained release (depot effect)

Question 10

What oils do we choose for oral emulsions

Answer 10

castor oil, cod liver oil, olive oil, liquid paraffin (mineral oil)

Question 11

What oils for IV emulsions

Answer 11

Cotton seed

Question 12

What oil for topical emulsions?

Answer 12

turpentine, benzyl-benzoate, liquid paraffin

Question 13

What are our choices for water phase?

Answer 13

water
glycerol
PEG

Question 14

What is the mechanism of action for emulsifying agents?

Answer 14

Lowers the interface tension making it more miscible
puts charges on droplets

Question 15

What is part of egg yolk that acts as a emulsifying agent?

Answer 15

lecithin

Question 16

What type of emulsions would lotions, creams, and ointments be?

Answer 16

L=o/w
C=both
O= w/o

Question 17

What are the natural emulsifying agents?

Answer 17

Plant= tragacanth, xanthin gum= o/w
Animal= gelatin, lanolin= w/o

Question 18

What are some semi synthetic emulsifying agents?

Answer 18

MC
CMC

Question 19

What are anionic surfactants?

Answer 19

have a negative changed head
Soft and hard soaps

Question 20

What are soft soaps and give examples?

Answer 20

alkali metal and ammonium soaps
ie) sodium,K, NH3 stearate

Question 21

What are hard soaps and give examples

Answer 21

Divalent or trivalent metals
Ie) calcium oleate

Question 22

What is special about soft soaps?

Answer 22

can be formed in situ

Question 23

What emulsions do soft soaps make

Answer 23

o/w

Question 24

What emulsions do hard soaps make?

Answer 24

w/o emulsions

Question 25

What emulsions do detergents make?

Answer 25

o/w

Question 26

What is a detergent agent?

Answer 26

sodium lauryl sulfate

Question 27

Of the three anionic surfactants (soft, hard soaps, detergent) which is most common and why?

Answer 27

detergent because resistant to hydrolysis

Question 28

What are cationic surfactants and give examples?

Answer 28

Have a positive charged head. Ie) quaternary ammonium compounds like benzylkonium chloride and benethonium chloride

Question 29

What is special about cationic surfactants?

Answer 29

can be used as preservative in ophthalmic formations

Question 30

What are non-ionic surfactants and give examples?

Answer 30

have a hydrophilic head no charge. ie) usually an alcohol, or fatty acid has moiety

Question 31

Of all surfactants which is most common and why?

Answer 31

non-ionic due to neutral at pH and resistant to acids and electrolytes

Question 32

If hydrophobic portion of non-ionic surfactant which phase is it soluble in?

Answer 32

oil phase

Question 33

Of span and tween which is hydrophobic and which is hydrophilic

Answer 33

tween= hydrophilic span= hydrophobic

Question 34

What is a zwitterionic surfactant?

Answer 34

carries both cationic and anionic charge.

Question 35

What are finely divided solids?

Answer 35

form a particulate layer around droplets to increase inter particle distances.

Question 36

What emulsions are formed from finely divided solids?

Answer 36

o/w emulsions but bentonite can also form w/o

Question 37

Examples of finely divided solids?

Answer 37

bentonite, veegum

Question 38

What are auxiliary emulsifiers?

Answer 38

are weak and need another one as well. They act by thickening

Question 39

Examples of aux emulsifiers?

Answer 39

stearic acid, cetyl alcohol

Question 40

When should we NOT use ionic emulsifiers and why?

Answer 40

NO for oral due to cationic being toxic and bad taste anionic is basic= NO for broken skin

Question 41

Which surfactants may be used in Parenteral?

Answer 41

NON-ionic= lecithin, polysorbate 80

Question 42

What are the three MOA of emulsifying agents?

Answer 42

1= Mono film- go to interface and reduces surface tension(surface agents) 2= Multi film- makes protective sheath and gives charge to droplets= repel (hydrocolloids) 3= Solid particle film- layer then swell to increase viscosity (FDS)

Question 43

CMC is a term we learned about, What does it mean and what does a LOW number indicate?

Answer 43

CMC= concentration of surfactant where micelles will form micelles WE WANT a High number because if it is low it will be coated before forming micelles.

Question 44

What does a low HLB indicate

Answer 44

lipophilic

Question 45

What does a high HLB indicate?

Answer 45

hydrophilic >10

Question 46

What is the formula for finding HLB of a mixture

Answer 46

HLB= y x HLB + (1-y) x HLB

Question 47

If we want a O/w emulsion what HLB are we expecting?

Answer 47

>8

Question 48

WHICH PHASE ALWAYS GETS POURED INTO THE OTHER ONE?

Answer 48

water phase into oil phase due to not wanting the oil phase to precipitate out.

Question 49

What are antioxidants we can add?

Answer 49

BHA,BHT, Vit e, Vit C

Question 50

What are some preservatives we can add and which phase do they like?

Answer 50

Methylparaben= water propylparaben=oil phase

Question 51

What can happen with the common preservatives and tweens?

Answer 51

parabens can bind and inactivate

Question 52

What are humectants and give examples?

Answer 52

Absorb water from air= keep moist ex) PEG, glycerol, sorbitol

Question 53

What is the dry gum method?

Answer 53

add gum to oil then add water to oil all at once to get emulsion

Question 54

What is the wet gum method?

Answer 54

add water to gum then get mucilage then slow addition to oil phase

Question 55

What type of mortar for natural ingredients?

Answer 55

not glass due to high energy to break it down

Question 56

Which method wet or dry is better?

Answer 56

no clear answer but wet gum works better for tragacanth

Question 57

What is special about lime water and cottonseed oil?

Answer 57

form in situ calcium oleate = hard soap= w/o emulsion

Question 58

What ways can we mix emulsions?

Answer 58

Mechanical stirrers= for low viscosity Homogenizers= no for high viscosity Ultrasonifiers= gentle and powerful Colloid mills= when need scaling up production

Question 59

What aux labels always?

Answer 59

for external use and shake well

Question 60

What three things can happen if the stability of emulsion is super low?

Answer 60

cream/ sediment flocculate coalescence

Question 61

Which way do particles move if creaming is happening

Answer 61

up

Question 61

Which way do particles move if sedimentation is happening

Answer 61

down

Question 62

How can we predict whether creaming or sedimentation may happen?

Answer 62

density of droplets and density of continuous phase

Question 63

How can we reduce creaming/sedimentation?

Answer 63

lower droplet size increase viscosity of continuous phase

Question 64

Is creaming or sedimentation reversible

Answer 64

Yes

Question 65

In stokes law what does a negative value indicate?

Answer 65

creaming

Question 66

What is stokes law?

Answer 66

V=d^2(Pint-Pext)/(18xnext) x g

Question 67

What does primary minimum mean?

Answer 67

very attractive potential

Question 68

What does primary maximum mean?

Answer 68

repulsion is greater= ideal for dispersion

Question 69

What does secondary minimum mean?

Answer 69

shallow attraction for easy dispersion

Question 70

Which is okay Primary max/min or secondary minimum

Answer 70

Primary min= NO hard to disperse Primary max= IDEAL Secondary min= not bad. just need to shake

Question 71

What is coalescence?

Answer 71

fusion of droplets which can eventually lead to separation

Question 72

How can we stop coalescence?

Answer 72

o/w= strength of mono films w/o= need long hydrocarbon chains of surfactants into oil phase

Question 73

What does flocculation mean?

Answer 73

aggregate

Question 74

Can coalescence be fixed?

Answer 74

NOOOOOOO

Question 75

What to do if it foams?

Answer 75

lower surfactant and mix slower

Question 76

What is BUD if water containing?

Answer 76

14 days

Question 76

What is BUD for external preps?

Answer 76

1 month