D8 Flashcards
What’s an emulsion?
It’s a liquid medicine in which one insoluble liquid is dispersed as microscopic globules in another liquid (both are immiscible
How does an emulsion look like
External or continuous phase ( the liquid vehicle)
Internal or dispersed phase ( the droplets)
Molecular film of emulsifying agents at the oil/ water interface
The types of emulsion
- Oil in water o/w Milky white
- Water in oil w/o translucent
- The third one can be multiple emulsions w/o/w or o/w/o which is droplets within the droplets
Stability
They are physically unstable and they would want to separate
Creaming
When the oil collects near the surface
Cracking
This is the separation phase, it’s an irreversible Reaction, which is very different from caking. The separation happen because the density of oils is less than water
Cracking
This is the separation phase, it’s an irreversible Reaction, which is very different from caking. The separation happen because the density of oils is less than water
Preventing creaming and cracking by droplet size
The smaller the droplets the more stable
Shelf like up to 2 years which is very short.
Preventing creaming and cracking by temperature
Shouldn’t be exposed to heat or temperature fluctuations, freezing causes rapid separation, the crystals destablise the film between oil and water
What type of emulsion is more stable
The oil in water is more stable than water in oil
That’s because creams are more stable than liquid emulsions
What are emulsifiers
( surface active) long molecules that locate at the oil water surface interface
What are emulsifiers 2?
They are amphiphiles as they have hydrophilic head and hydrophobic tail
Position of amphiphiles
Between water and air, The hydrophilic head faces the water and the hydrophobic tail faces the air
Position of emulsifiers
Between water and oil the hydrophobic tail faces the oil while hydrophilic head faces the water
The types of emulsifiers including charges
Anionic which has a negative charge
Cationic which has a positive charge
Non-janie which has no overall charge
Why we don’t use single charged amphiphile
Positive charged ones repel the internal phase droplets
Negative repel each other at the surface
Can react with drugs or excipients
Why do we use mixed emulsifiers
We use charged and non-ionic
Dense inter facial film
Better for stabilising emulsions
What are the stability issues with oil in water emulsions
They have a huge surface area internally which makes it very sensitive to hydrolysis and fat oxidation so usually need oil soluble antioxidant
What are the issues with oil in water
The ester bonds hydrolyse
The unsaturated bonds oxidise
Forming short chain fatty acid
Then they become rancid( bad smell and change in appearance/ taste)
Stability issues with oil in water emulsions
Microorganisms grow well
Preservative must be added, but can destabilise the emulsifier film making it insectivore
Are emulsions stable
They are physically, chemically and mierobiologically unstable
The oral Route, by mouth
More palatable
easier to administer
More eligestible due to large surface area of droplets
Topical Route
Lotions
creams
What’s a cream
Emulsion to be applied on the skin in which one of the 2 phases is a semi solid or a wax
Creams
Can be oil in water or water in oil
Insoluble powders
Ingredients that are soluble either in oily or aqueous phase
