Physiochemical aspects Flashcards
what are the reasons for formulating drugs?
allowing convenient dosing of drugs
consistent dosing
appropriate systemic exposure
appropriate concentration of drug
what are the general industrial challenges in drug formulations?
solubilisation of a poorly soluble molecule
size reduction of a particle for a particular route
what are the preclinical industrial challenges in drug formulations?
high dose of compound administered
restriction on amount of drug available
rapid throughput in discovery
examples of oral complex formulations?
nanoparticles
solid dispersions
lipidic formulations
complex
what are intravenous drugs?
bolus or infusion
includes solutions, emulsion
given at a 25 degree angle
what are intraperitoneal drugs?
what is a suspension?
absorption of surfactants, suspension instability
where insoluble solids are dispersed as fine particles
solid-in-liquid colloid
what is a colloid?
a disperse system where there’s one phase with tiny particles
what is a n emulsion?
liquid wher one insoluble liquid is suspended in a microscopic droplets (globules) in another
liquid-in-liquid colloid
ususlally oil and water which are immicible- two spereate phases
why are disperse systems used?
single phases may not be able to provide all formulation requirements
properties of emulsions?
require emulsifier for stability
produced by homogenization
multiple emulsions possible
what are the physical signs of instability?
caking
separation
what is caking?
high density sediment of particles
difficult to redisperse
what is separation?
particles fall due to density differences
can redisperse by shaking
how can particles remain suspended?
reducing particle size
matching density to vehicle
increasing viscosity of vehicle
what are thickening agents for?
increasing viscosity
what are entangled soluble polymer for?
polymer chains are really long and entangle each other and increase viscosity
examples of thickening agents?
Natural Polysaccharides
Cellulose ethers
gelatin
PVP
what are minerals?
small plat like particles dispersed in the liquid increasing viscosity by charge dispersal
what is flocculation?
loose particle aggregates
how are suspension particles kept suspended?
what are the consequences of sedimentation redispersed?
flocculated structures are porous and don’t form a cake
redispersed by shaking
what is shear thinning?
increasing shear, decreasing viscosity so it flows
what is Ostwald ripening?
due to high surface free energy, small particles dissolve
