[PHA 619 LAB] Prep 27 - Non-Aqueous Liquids: Emulsions

It is a two-phase system in which one liquid is dispersed in the form of small globules throughout another liquid in which it is immiscible.

Emulsion

It is also known as the internal phase or discontinuous phase.

Dispersed Liquid

It is also known as the external phase or continuous phase.

Dispersion medium

It is also known as the emulsifying agent , dispersing or stabilizing agent.

Intermediate agent

It is an agent added to form oil-in-water or water-in-oil system due to its hydrophilic head and hydrophobic tail.

Emulsifier

What are the dispersed liquid and the dispersion medium in an oil-in-water emulsion?

Dispersed Liquid - Oil

Dispersion Medium - Water

What are the dispersed liquid and the dispersion medium in a water-in-oil emulsion?

Dispersed Liquid - Water

Dispersion Medium - Oil

What are the types of natural emulsifying agents?

- Animal

- Vegetable

Examples of animal emulsifying agents

- Gelatin

- Egg yolk

- Casein

- Woolfat

- Cholesterol

Examples of vegetable emulsifying agents

- Acacia

- Tragacanth

- Chondrus

- Pectin

- Carrageenan (from seaweeds)

What are the types of synthetic emulsifying agents?

- Finely-divided Solid

- Colloid

- Anionic

- Cationic

- Non-ionic

- Amphoteric

Examples of finely-divided solids that are emulsifying agents

- Magnesium hydroxide, Mg(OH)2

- Aluminum hydroxide, Al(OH)3

- Magnesium trisilicate

Examples of colloid emulsifying agents

- Kaolin

- Bentonite magma

Example of anionic emulsifying agents

Sodium lauryl sulfate (SLS)

Example of cationic emulsifying agents

Benzalkonium chloride

Examples of non-ionic emulsifying agents

- Polyethylene Glycol (PEG) 400

- Spans and Tween (Polysorbate)

Example of amphoteric emulsifying agents

Lecithin

What are the three types of emulsion?

- Simple

- Multiple

- Microemulsion

Type of emulsion that only consists of one dispersed liquid and one dispersion medium

Simple Emulsion

- ex. O/W and W/O

Type of emulsion where one emulsion is dispersed within another, creating a "double emulsion". It is both oil-in-water and water-in-oil (or vice versa). It needs two surfactants or emulsifying agents to stabilize the system.

Multiple Emulsion

- ex. O/W/O and W/O/W

Type of emulsion that is the most stable of the other types; dispersed liquid is in very small globules

Microemulsion

Particle size of microemulsions

100-1000 A (10 nm-100 nm)

1 ahmsstrong is equal to how many nanometers?

1A = 0.1 nm

What are the three methods of preparing emulsions?

- Wet Gum (English)

- Dry Gum (Continental)

- Bottle or Forbes

These two methods are used to prepare emulsions of fixed oils.

Wet Gum and Dry Gum

This method is used to prepare emulsions of volatile oil.

Bottle/Forbes

(True/False) Regardless whether dry or wet gum method, the emulsion is triturated in different directions.

False

- One direction only

What is the ratio of oil, water, and gum in forming the primary emulsion using wet and dry gum method?

4:2:1 (O:W:G)

What is the ratio of oil, water, and gum in forming the primary emulsion using bottle/forbes method?

2:2:1 (O:W:G)

In wet gum method, gum is first triturated with _________ to form a mucilage.

Water (2 parts)

After creating the mucilage using the wet gum method, how is oil added in the mixture?

Added slowly, in portions, while triturating

In dry gum method, gum is first triturated with _________ until the powder is thoroughly wetted.

Oil (4 parts)

After creating the mixture using the wet gum method, how is water added in the mixture?

Added all at once, then mixed vigorously

In dry gum method, what should be the primary emulsion formed?

Creamy white and produces a crackling sound as it is triturated

What mortar and pestle should be used in making emulsions?

Dry wedgewood or porcelain mortar and pestle with ROUGH inner surface

How is the bottle/forbes method of preparing emulsion performed?

1. Powdered acacia (1 part), is placed in a dry bottle.

2. Two parts of oil are added and the mixture is thoroughly shaken in the capped container (bottle).

3. A volume of water approximately equal to that of the oil is then added in portion and the mixture thoroughly shaken after each addition, thus formed a primary emulsion

4. Then it may be diluted with water or aqueous solution of other formulative agents

In bottle method, how is water added to the bottle after shaking?

Added in portions

What are the criteria in selecting the emulsifier?

1. Compatible with the other formulative ingredients.

2. It will not interfere with the stability or efficacy of the therapeutic agent.

3. Stable and do not deteriorate in the preparation.

4. Nontoxic with respect to its intended use.

5. Possesses little odor, taste, or odor.

What problems are encountered in emulsions?

- Creaming

- Cracking

- Phase inversion

It is the temporary separation of the two phases. It can return to a homogenized form by shaking. It may come as an aggregate of globules of internal phase that rise to the top, or it may fall to the bottom of the emulsion.

Creaming

It is the total separation of the two phase with coalescence.

Cracking

It is the evaporation of water wherein the oil-in-water emulsion becomes water-in-oil due to evaporation. The amount of water is smaller when oil becomes the dispersion medium.

Phase inversion

Category of mineral oil emulsion

Oral emulsion

Method of identifying emulsion wherein the addition of a drop of water will not change the emulsion if it is an oil-in-water emulsion. Otherwise, a separation of layers occurs.

Drop Dilution Test

Method of identifying emulsion wherein water-soluble or oil-soluble dyes are added to determine if the emulsion is either oil-in-water or water-in-oil

Dye Solubility Test

It is an oil-soluble dye added to test whether the emulsion is a water-in-oil.

Sudan red

It is a water-soluble dye added to test whether the emulsion is an oil-in-water.

Amaranth green

Method of identifying emulsion wherein a positive result for oil-in-water emulsion is when the bulb glows. No glowing of light occurs if it is a water-in-oil emulsion.

Electric Conductivity Test

Method of identifying emulsion wherein a spotty fluorescent confirms a water-in-oil emulsion

Fluorescence Test

What are the methods of identifying an emulsion?

- Drop Dilution Test

- Dye Solubility Test

- Electric Conductivity Test

- Fluorescence Test

Synonyms of mineral oil emulsion

Liquid petrolatum emulsion

Desired description of mineral oil emulsion

It has a whitish yellow color.

Use of mineral oil emulsion

Lubricating cathartic

What is the usual dose of mineral oil emulsion?

30 mL

It is an agent that softens the feces and reduces friction between the stool around the intestinal wall.

Lubricating cathartic

Formulation of mineral oil emulsion

- Mineral oil (15 mL)

- Acacia (3.75 g)

- Syrup (3 mL)

- Vanillin (1.20 mg)

- Alcohol (1.80 mL)

- Purified water, qs ad (30 mL)

What vehicle is used in mineral oil emulsion?

Purifed water

Label used in mineral oil emulsion

White label with shake well

Container used in mineral oil emulsion

30-mL wide-mouthed amber bottle

Use of mineral oil in mineral oil emulsion

Cathartic

Use of acacia in mineral oil emulsion

Suspending/emulsifying agent

Use of syrup in mineral oil emulsion

Sweetening agent

Use of vanillin in mineral oil emulsion

Flavorant

Use of alcohol in mineral oil emulsion

Preservative

(True/False) Emulsion is less palatable than the unemulsified oil.

False

- MORE palatable due to added sweetening/flavoring ingredients