Exam III Emulsion

• A dispersion of immiscible liquids (polar and non-polar)
• Hetergenous system: immiscible liquid intimatly dispersed in another lquid in the form of droplets or globule (neither miscible nor soluble with vehicle)

• Dispersed phase: Internal phase, discontinuous
• Dispersed medium: External phase, continuous
• Emulsifying agent: Emulsifier, surfactant, wetting agent

• Allow for a stable and homeogenous preparation mixtures of oils and aqueous drugs
• Liquid drug as minute particles rather than large globules

• They mask the taste of the oil
• Enhance the absorption, oil as small globule are more digestable and absorbed

Can place the irritating compounds in the internal phase.

• Also called: Surface active agent
• Promote the lowering of interfacial tension between two immiscible liquids
• Facilitate the breaking up large globule into smaller globules
• Decreases the tendency for globule to join, or coalesce

Causes small drops to join or coalesce, forming one larger drop

• The emulsifier forms a spherical droplet around the internal phase
• Smallest surface area possible

• The emulsifier forms layers surrounding the internal phase
• The emulsifiing agent, hydrophilic portion, and hydrophobic agent will ORIENT themselves into each phase producing electrical forces that repulse approaching droplets
• The phase in which the emulsifing agent is more soluble is going to be the external phase, or the continuous phase

• Emulsifing agent surrounds the droplets of the internal phase as a thin layer adsorbed on the surface of the droplet
• Enough film-forming material must be available to coat the entire surface each drop of internal phase

Form hydrophilic colloids with water and favor preparation of o/w emulsion

• Acacia
• Tragacanth
• Agar
• Pectin

Produce o/w

• Gelatin
• Egg yolk
• Casein

• Contain hydrophilic and lipophilic
• The lipophilic portion in general accounting for the surface activity

Finely divided solid that will form o/w or w/o emulsion depending on which phase a larger volume

• Bentonite
• Magnesium hydroxide
• Aluminum hydroxide

• Thickening agents
• Stabilizers
• USed for external use only

• 4:2:1 ratio (4ml oil, 2ml water, 1g emulsifier)
• OIL + GUM =hydrocoloid: Rapid tituration for a very short time to reduce globule size of internal phase
• Water phase adding all at once with rapid trituration until snapping sound is made = formation of primary emulsion (creamy white)
• Other liquid ingrediants are added with slow trituration
• Solid
• Alcohol
• Rinse the mortar and pestle to get rest of emulsion

• Preparation of a mucilage: small quantity of water and gum with trituration until uniform
• Oil is added with small proportion with rapid trituration, will make thick and viscous mixture, which is the primary emulsion
• More water is added with rapid trituration
• Other ingredient are added

• IS a variation of the dry gum metod
• Emulsifier + volitle oil with rapid shaking
• Water added rapid shaking makes the primary emulsion

• Oil and water phase are made seperately with dissolved ingredients
• Each phase is heated 60 to 70 oc
• INTERNAL phase is stirred into the external phase
• Product is cooled
• Gentle and periodical stirring unteal cooled (congealed)

• Hand homogenizer will reduce globule of internal phase by forcing the mixture through small inlet orifice at a high pressure
• Mechanical stirrers (mixers)

Calcium soap (w/o emulsion) = Ca hydroxide solution (lime water) + vegetable oil

• Hydrophile/lipophile balance
• Decribe the characterisics of a sufactant based on its chemical structure (hydrophilic and lipophilic portion)
• Each emulsifing agent has a HLB number which indicative of the substances polarity

BOTH

• LOW = Lipophilic predominantly and less polar
• Useful for water in oil emulsions

• HIGH = Hydrophilic and highly polar materials
• Useful for oil in water emulsions

Aqueous

Presented in the un-ionized state (effective against bacteria) must be neither bound nor absorbed to any agent in the emulsion or container

Parabens

Antioxidants

• MIxed with surfactant before addidtion to aqeous phase
• Use of cosolvent system to incorporate flavor

• Tight containers
• Oral emulsions wide opening
• Squeeze bottle: topical liquid emulsions
• Tubes and pump containers: viscous creams
• Avoid extreme cold and hot will cause to go out of emulsion
• Label should include shake well

• decrease globule size of the internal phase: by useing a shearing action of mortar and pestle or a hmogenizer
• TO have the optimun oil to water ratio with the internal phase be 40 percent of total product
• Increasing the viscosity of the system, add a substance that is soluble in or miscible wih the external phase

• Aggregation
• The internal phase tend to form aggregates or globules upoon standing
• Aggregates may rise to the top of the emulsion or fall the bottom
• This is a reversible process and shaking amy redistribute creamed portion

• Cracking or braking
• When the globules of the internal phase coalesce and this phase is separated into a layer
• This is an irrevesible process because the protection durrounding the globules of the internal phase is destroyed
• Additional emulsifying agent and reprocessing are usually necessary

From o/w to w/o or vice-versa

• Biphasic oil/water system
• Optically transparent (solution like)

15-18

• 100-5000 Angstrom
• 1 Angtrum= one ten-billonth of a meter