absorption of molecules 1 Flashcards
solubility definition
the amount that goes into a solution when equilibrium is established between the solute in solution and the excess substance
what are the 3 stages of the solution process
- a drug molecule is removed from crystal
- a cavity from the molecule is created in the solvent
- the drug molecule inserts into this cavity
when is a solution described as saturated
when a solution contains a drug at the limit of its solubility at any given temperature and pressure
what happens if solubility limit is exceeded
solid particles of solute may be present
what is the dissolution rate
the rate by which
something dissolves
what is the solubility
the amount that can be dissolved
how does temp affect solubility
increasing temp = increase in solubility as it increases the kinetic energy
how does BP and MP affect solubility
they reflect the strengths of interactions between the molecules
as MP and BP rises, solubility drops
how does surface area affect solubility
increasing surface area, increases solubility
how do polar groups such as -OH affect solubility
they increase solubility
how do non polar groups such as -CH3, -Cl affect solubility
they are hydrophobic so decrease solubility
how does ionisation affect solubility
it increases solubility
why do drugs partition between solvents
due to difference in solubility in different phases
eg drugs going between aqueous and lipid phases
antibiotics portioning into microorganism
drugs partition into plastics
what is logP a measure of
lipophilicity/hydrophilicity
log P calc
logP=
log( conc of oil / conc of water)
