Suspension Theory Flashcards
Suspension
A suspension is a dispersion of solid particles of a material in a liquid medium + is cloudy
The particles in a suspension generally have a higher density than the
Liquid medium + will settle over time, giving rise to dose homogeneity issues
Surface
A surface is an interface between 2 phases, where one phase is a solid
Properties of a surface
Surfaces behave differently to the bulk material
Nearly everything happens at the surfaces - even though they are a small % of the whole
All interfacial phenomena apply
Surface science
The study of surface phenomena
=> Properties of surfaces of bulk material
=> Interactions with fluids
=> Interactions with other surfaces
Suspension
A “suspension” is a dispersion of a solid material (the dispersed phase) in a fluid ( the continuous phase)
Colloid
A suspension where the particles are in the size range up to approx. 1 micro metre
=> Some very large molecules (eg DNA) behave like colloids
Colloid science
The study of colloids
=> Interactions:
Particle/ particle and particle / medium
Suspension doseability is vital
Each dose must contain the correct amount of drug
Each dose must be exactly the same
Particles should not interact
Particles should not sediment or cake
Particle behaviour in suspensions. Facts to consider
Charge on the particle surface Electrical double layer DVLO theory Sedimentation kinetics Surface wettability Effect of added materials Physicochemical nature of solid material, eg solubility