Emulsions Flashcards
(40 cards)
Which type of emulsions are developed to produce a sustained release of API
Multiple emulsions
What is a microemulsion?
Dispersed globules are of colloidal dimensions (1nm-1 microm)
Usually transparent
What are nanoemulsions?
- They are of colloidal nano dimensions (less than 200nm
- usually transparent
Explain the 3 types of tests for identifying emulsion types
- Diultion test
- o/w can be diulted with water
- w/o can be diluted with oil - Conductivity test
- conductivity of water as a continuous/external phase is much more efficient than oil as the external phase - Dye-solubility test
- oil-soluble and water-soluble dyes can be used to determine the type of emulsion formed
What type of emulsions are usually for oil administration
Mostly o/w to ensure a pleasant taste
What type of emulsions are used for INTRAVENOUS administration
must be oil/water
What type of emulsions are used for INTRAMUSCULAR administration
water/oil for sustained release
What emulsions are used for external administration if you want:
- no grease
- water-washable
water/oil
What emulsions are used for external administration if you want:
- grease
- occlusive
- water repellent film
water in oil
What additives are used for emulsions? (3)
Antioxidants
Preservatives
Humectants
Which oils are used for oral administration (4)
- liquid paraffin
- Caster oil
- Cod liver oil
- Peanut oil
Which oils are used for intravenous administration? (3)
- cottonseed oil
- soya bean oil
- safflower oil
Which oils are used for external administration? (3)
- turpentine oil
- benzyl-benzoate
- various oils
What are the desirable properties of non-ionic emulsifiers
Which type of emulsifying agent should NOT be given orally?
Which type of emulsifying agents can suitable for parenteral injections?
non-ionic emulsifiers
- less toxic, less irritant
Ionic emulsifiers
Only some non-ionic surfactants (lecithin, polysorbate (tween 80), poloaxamers
Explain the type of charge that synthetic and semi-synthetic anionic surfactants
- Hydrophilic head is negative
- orient in aqueous environment & form micelles
What are types of anionic surfactants and their emulsion type.
Only soaps of divalent and trivalent metals form water/oil (calcium oleate) (in situ)
- alkali metal and ammonium soaps (sodium stearate) (in situ)
- amine soaps (triethanolamine stearate)
- sulfated compounds (sodium lauryl sulfate)
Explain Cationic surfactants and what type of surfactant agent they are and their emulsion type
- Hydrophilic head is positive
- quaternary ammonium compounds (o/w)
What are some examples of non-ionic surfactants? what are their emulsion types?
- Polysorbate tweens (o/w)
- Fatty polyglycol ethylenes (o/w)
- Glycerol esters (w/o)
- Sorbiton esters span (w/o)
What are examples of naturally occuring emulsifying agents? determine their emulsion type
Polysaccharides acacia o/w
methylcellulose o/w
Sterols (cholesterols) w/o
What are some examples of Antioxidants additives? what are they used for
To prevent rancidity and auto-oxidation
BHA, BHT (butyls)
What are some examples of preservatives?
Cationic surfactants
- quarternary ammonium compouds
- benzoic acid, parabens
What is the role of humectants and give examples
Reduce evaporation of the water phase to prevent drying (absorbs water from air)
Examples:
- propylene glycol
- glycerol
- sorbitol
What are the advantages of polysorbates as surfactants?
-Versatile
-can be used in all dosage forms
- safe
- non-toxic
- non-irritating
What is the relationship between surfactant concentration and interfacial tension?
How do they orient themselves?
As we increase surfactants, the interfacial tension decreases up until CMC (micelle formation, then stays constant)
oil/water interface
