Solubility Flashcards
where must a drug be in order to work?
in solution
what is the importance of the blood concentration/time graph
it is important for determining therapeutic window
define solvation (dissolution)
the transfer of molecules or ions into the solvent
define hydration
the transfer of molecules or ions into water
define solubility
the amount of solute needed to form a saturated solution in a given quantity of solvent and experimental conditions
define saturated solution
when no more solid will dissolve and dynamic equilibrium exists between the solution and the undissolved solid
define precipitation (crystallization)
the opposite of solvation; the solvent cannot accommodate more solute, so the solute precipitates back into solid form
list the 2 opposing processes
solvation and dissolution (precipitation and crystallization)
define cohesion
attraction between molecules of the same substance
define adhesion
attraction between molecules of different substances
define intermolecular forces
> the ability of the solvent to break up the cohesion forces between solute particles and create adhesive forces
the ability of the solute to break apart
list the 6 types of intermolecular forces
- ion-dipole
- h bond
- dipole-dipole
- ion-induced dipole
- dipole-induced dipole
- van der waals (london dispersion)
define repulsion
reaction between 2 molecules that forces them apart
in order for molecules to interact, the forces must be balances in an __________
energetically favored arranged
define energetically favored
> the intermolecular distances and intramolecular conformations where the energy of the interactions is maximized based on the balancing of attraction and repulsive forces
must be favorable for adhesion to occur
define apparent solubility
> the observed solubility, can be affected by kinetic factors
does not change intermolecular forces
define supersaturated
a solution that contains greater amounts of solute than needed to form a saturated solution
>greater than equilibrum
what is the key to solubility
like dissolves like
list the 2 characteristics of a molecule that can interact with water
- hydrophilic
- lipophobic
list the 2 characteristics of a molecule that cannot interact with water
- hydrophobic
- lipophilic
list the characteristics of solutes that dissolve in polar solvents
- salt forms/electrostatic charge
- hydrophilic groups
- low molecular weight
- increased branching
list the characteristics of solutes that dissolve in nonpolar solvents
- non ionizable
- hydrophobic groups
- high molecular weight
list the 6 main factors impacting solubility
- IMF
- solvents
- salt form
- solid state/particle size
- pH/ionization
- temperature
define dipole
results from the unequal sharing of electrons making up a covalent bond
explain how water solubilize salts
dissociates them and insulates ion from each other using ion-dipole forces
explain how was solubilizes organic molecules
donates and accepts hydrogen bonds
how do alcohols work as solvents?
> dissolve non-ionized forms better than salt forms of organic compounds
dipole-dipole or dipole-induced dipole forces
list the 4 types of alcohol solvents
- alcohol or ethanol
- glycerin
- proplyene gylcol
- polyethylene glycol
explain how non polar solvents solubilize hydrophobic solutes
induced dipole-induced dipole forces (van der waals)
define dielectric constant
as the polarity of a substance is higher, the substance is more polar
what is the goal of mixed solvents
to increase the solubility of drugs/solutes by mixing 2 or more solvents
define co-solvency
can increase the solubility of drugs/solutes by mixing 2 or more solvents
how are mixed solvents and hydrophobic drugs used together
can be used to increase the aqueous solubility of hydrophobic drugs by mixing different polarities
how do you calculate dielectric constant of a mixture
multiplying the volume fraction of each solvent times it dielectric constant and adding
how are drugs in salt forms solubilized
ion and formal dipole bonding
list 3 physical modifications that improve solubility
- particle size reduction
- modification of solid state
- drug dispersions in carriers
list the 4 chemical modifications that improve solubility
- change in pH or buffer
- prodrug
- complexation
- salt formation
