disperse systems and suspensions Flashcards
what are the advantages of solution
- heterogenous
- mixing/handling
- dosing
- patient acceptability
disadvantages of solution
- lack of chem, microbiological and physical stability
- patient unacceptablity
meaning of hydrophobic and lipophilic
tends to dissolve in lipids
meaning of hydrophilic and lipophobic
tend to dissolve in aqueous systems
what is a disperse system
one component (the dispersed phase) is dispersed through the other (the continuous phase)
do the phases in a disperse system change
no
do the phases in a solution change
yes
what is a solid dispersed in a solid called
solid suspension
what is a liquid dispersed in a solid called
solid emulsion
what is a gas dispersed in a solid called
solid foam
what is a solid dispersed in a liquid called
sol, suspension
what is a liquid dispersed in a liquid called
emulsion
what is a solid dispersed in a gas called
solid aerosol
what is a gas dispersed in a liquid called
a foam
what is a liquid dispersed in a gas called
liquid aerosol
can a gas be dispersed in a gas
no
what does lyophobic mean
has aversion to the solvent type
what does lyophilic mean
has an affinity for the solvent type
what influences physical and chemical behaviour of suspension
particle size
when would a suspension be optically clear and not cloudy
when the size of the particles in within the colloidal range
advantages of suspensions
- formulate API with low solubility in continuous phase
- patient acceptability
- drugs that have unpleasant taste in soluble form can be made insoluble
- increased absorption in oral suspensions
- stability of drug increased
- can modify drug release
disadvantages of suspension
active ingredient can settle at bottom of bottle
what can change the behaviour of solid particles in suspension
excipients
how does sodium chloride at low/medium concentration impact the electrical double layers
it affects the diffuse layer
as their is easier neutralisation of remaining surface change on particle
how does sodium chloride at high concentration affect the electrical double layer
it affects the diffuse and fixed layer
when can particles in suspensions agglomerate/aggregate
when
- exposed to heat
- shaken vigorously
- added to other solutions (esp salts)
What forces do particles have in a solution?
Both forces of attraction and repulsion
What happens to the repelling force as two particles approach each other?
The repelling force gets stronger
What effect does vigorous mixing have in a colloidal suspension?
It forces particles together, making them attracted and can start to coagulate
What changes when conditions change in a colloidal system?
The double layer changes
Fill in the blank: In a colloidal suspension, vigorous mixing can lead to _______.
coagulation
True or False: In a solution, particles only experience forces of attraction.
False
