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pharmaceutics > Emulsion > Flashcards

Emulsion Flashcards

1
Q

emulsion

A

it is biphasic system of two imiscible liquid where one liquid (dispersed phase) is disperesed into another liquid (dispertion medium) with the help of any emulsifying agent.

ex) vanishing cream, gel lotion, ointment

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2
Q

classification of emulsions

A

1- oil in water
2- water in oil
3- multiple emulsion
4- microemulsion

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3
Q

oil in water emulsion

A

this are those emulsion in which dispersed phase is oil and contineous phase is water
Ex) milk, lotions liniments

-non-greasy nature

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4
Q

water in oil emulsion

A

this are those emulsions in which disperesed phase is water and contineous phase is oil
ex) Butter and cold creams

-greasy nature

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5
Q

multiple emulsion

A

those emulsion which are made of more then two phase.
-in which the droplets of one liquid are dispersed in droplet of second which is further dispersed in dispersion medium

  • prepared to prolong the release of druges
  • enhance bioavailibiity
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6
Q

types of multiple emulsion

A
  • oil in water in oil: in which o/w emulsion is dispersed in another oil phase
  • water in oil in water: in which w/o emulsion is dispersed in another water phase
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7
Q

micro-emulsion

A

-those emulsion in which postion size of dispersed phase is less than 1 U (micrometer)
-it is clear, tansparent and thermodynamically stable as compared to normal emulsion

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8
Q

stability of emulsions

A

a stable emulsion is one in which the globules (dispered phase) retain their size and as well as remain uniformly distributed throughout the contineous phase.

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9
Q

instability that occur during storage and formulation of emulsion

A
  • creaming
  • coalecence
  • breaking
  • flocculation
  • phase inversion
  • physical and chemical properties
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10
Q

creaming

A

it is a reversible phernomenan. in which droplet of dispersed phase come together or deposite at the surface of the emulsion

-o/w: in this, oil have low density so they come together at the surface of emulsion, upward creaming
-w/o: in this density of water (dispoersed phase) is more than continous phase, so particles come together at the bottom of emulsion, downward creaming

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11
Q

coalescence

A

in emulsion oily partiles (dispersed phase) because of sticky nature attract each other and they aggregate to form big particles

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12
Q

breaking (cracking)

A

due to inproper mixing of oil and water in emulsion, emulsion get separated into two layers i.e oil in water
- it is also occured due to improper ratio of oil and water

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13
Q

flocculation

A

in this due to increased surface free energy particles get aggregated to form floccules to decrease surface area

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14
Q

phase inversion

A

in this, the phase of emulsion get inverted i.e o/w -> w/o

-it happened due to mixing problem or by choosing wrong dispersed phse duing formulation

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15
Q

physical and chemical property change

A

to prepare an emulsion, we use emulsifying agent to mix and make stable emulsion
-sometimes addition of agent causes changes in properties like color, pH, odour, taste, etc

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16
Q

theories of emulsion

A

those theories which make and keep emulsion stabel
1- monomolecular theory
2- multimolecular theory
3- solid particle theory

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17
Q

monomolecular adsorption theory

A

-during preparation of emulsion the oil/water droplet get dispersed in contineous phase, particle get atomized (reduce particle size)
-due to small particle size surface area increases which further increases the surface area free energy, therefore system becomes unstable
-to resolve this problem or to make system stable we add surantants or emulsifying agent which reduces the interfacial tension or surface area of dispersed droplet

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18
Q

multimolecular adsorption theory

A

-monomolecular and multimolecular theory both used to stop flocculation, coalescence, also prevent the breaking of emulsion
-in this, emulsifying agent small-small particles join together and cover dispersed partciles and make multimolecular film

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19
Q

solid particle adsorption theory

A

-in this, we add a solid emulsifying agent in emulsion which increases the viscocity of emulsion
-it also prevent (reduce) coalescense of dispersed particles

20
Q

formation of electrical double layer

A

-in emulsion, oil droplets contain either negative or positive charge.
-due to present of charge they develop electrical double layer.
-due to this oil droplets produce repulsion force into eachother and they remain suspended

21
Q

formulaion of emulsion

A

-dry gum method
-base gum method
-bottle method

22
Q

dry gum method (w/o)

A

-take a pestle and mortar
-add gum (emulsifying agent) to it
-triturate it and then add some part of oil and triturate
-again add some more oil and tritarate until recieve the clicking sound
-then add water by part with trituration
-no make up the volume with bulk phase
-ratio = O:G:W = 4:1:2

23
Q

wet gum method (o/w)

A

-take a pestle and mortar
-add gum to it and triturate
-add some water to gum and triturate when adding more water until mucillage forms
-then add oily part slowly-slowly with tituration
-no make up the volume with bulk phase
-ratio is kept same

24
Q

bottle method

A

this method used to prepare emulsions of volatile oils or substance having very low viscocity
-1 part gum placed in dry bottle then 2 parts of oil are added, now shake the mixture
-a volume of water (approx. equal to oil) is added in portion then again shake
-now, mix it with proper volume of water
-on large scale this process is done inside botte or along with propilller movement

25
Q

formulation by HLB method

A

-HLB= hydrophilic lyophilic balance
-with the help of HLB method we choose the emulsifying agent which we used in preparations of emulsion
-o/w emulsifying agent = 8-16
-w/o= 3-6

26
Q

prevention of emulsion

A

-we have to keep emulsion stable and effective till expiry date for this, we have to preserve emulsion from micro-organism and oxidation
-emulsion:
-not change their nature and property
-not heat oil and water with each other
-stable

27
Q

preservation from microorganism

A

-micro-organism may arrise in emulsion due to carbon covalent of emulsion or due to present of high water content
-for this, we add preservative like methyl paraben, propyl paraben, benzoic acid, etc which inhibit the growth of bacteria
-preservative should be
nonirritant and non toxic
tasteless, colorless, and odorless
should be stabel

28
Q

prevention from oxidation

A

oxygen present in atmosphere cause oxidative such as ranicidity and spoilage for this, we use some antioxidant which can prevent the changes occurs due to atmospheric oxygen
-antioxidan should be
non toxic and non-irritant
effective at low concentration
ex) BHT (butylated hydroxytoluene), Ethyl and propyl gallate etc.

29
Q

rheological properties of emulsion

A

these properties of emulsion are related to flow of emulsion

applications:
- spreadibiblity
- removal from container
- flow of of emulsion through hypodermic needle
- proper mixing (during manifacturing)

30
Q

newtonian flow

A

this type of flow show by dilute emulsion
ex) micro-emulsion

30
Q

rheological property of emulsion can be controlled by

A

-concentration of dispersed phase
-particle size of dispersed phase
-viscocity of contineous phase
-nature and concentration of emulsifing sytem

30
Q

non-newtonian flow

A

this type of flow show by concentrated emulsion
-optimum viscocity is desirable for good stabiliy of emulsion
-the increase in the viscociy of the emulsion reduce the flocculation

31
Q

emulsifying agent

A

emulsifying agent is a surface active ingridient which absorbds at the newly formed oil water interface during emulsion preperation and it protects the newly formed droplets against immediate recolescence.
or
eumlsifying agents are agents that form a film around the dispersed globules or lower the interfacial tension in an emulsion

32
Q

natural EA

A

vegetable source- gum acacia, tragacanth, agar, starch, pectin

animal source- wool fat, egg yolk, gelation

33
Q

semi-synthetic polysaccharides

A

methyl cellulose
sodium carboxy

34
Q

syntheti agents

A

anionic
cationic
non-ionic

35
Q

inorganic

A

milk of magnesia
magensium oxide
magnesium trisilicate

36
Q

organic

A

carbowaxes
chloestrol
lecithins

37
Q

ideal properties of eulsifying agents

A

-should be capable of reducing interfacial tensios
-should be compatable with other ingrediesnts
-should be non-toxic
-should be capable to produce required consistency
-should be chemically stable

38
Q

dilution test

A

the addition of water to a w/o emulsion and oil to o/w emulsion would crack the emulsion and lead to separation of the phases

39
Q

conductivity test

A

when current is passed ti an emulsion cnnected ti a voltage bulb, the bulb glow if it is an o/w emulsion since water is a good conductor of electrivity

40
Q

floresencent test

A

oils give flouresence under UV light, while water does not. therefore, o/w emulsion shows a sotty pattern while w/o emulsions shows flouresence

41
Q

filter paper test

A

o/w emulsion should spread out rapidly when dropped on filte paper, in contrast, w/o will migrate slowly

42
Q

cobalt chloride test

A

filter paper soaked in cobalt chloride solutions and allowed to dry. turns blue to pink upon evaporation to o/w emulsion

43
Q

pharmaceutical applications of emulsions

A

-to mask the bitter taste of drugs
-o/w emulsion facilittes the absorption of water insoluble compounds comparing to their oily solution preparations
-o/w emulsion is conveniant means of oral administiration of water-insoluble lipids
-oil-soluble drugs can be given parenterally in for of an oil-water emulsion
-an emulsion can be used for external applications in cosmetic and therapeutics uses

pharmaceutics (39 decks)

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