Solubility

Question 1

where must a drug be in order to work?

Answer 1

in solution

Question 2

what is the importance of the blood concentration/time graph

Answer 2

it is important for determining therapeutic window

Question 3

define solvation (dissolution)

Answer 3

the transfer of molecules or ions into the solvent

Question 4

define hydration

Answer 4

the transfer of molecules or ions into water

Question 5

define solubility

Answer 5

the amount of solute needed to form a saturated solution in a given quantity of solvent and experimental conditions

Question 6

define saturated solution

Answer 6

when no more solid will dissolve and dynamic equilibrium exists between the solution and the undissolved solid

Question 7

define precipitation (crystallization)

Answer 7

the opposite of solvation; the solvent cannot accommodate more solute, so the solute precipitates back into solid form

Question 8

list the 2 opposing processes

Answer 8

solvation and dissolution (precipitation and crystallization)

Question 9

define cohesion

Answer 9

attraction between molecules of the same substance

Question 10

define adhesion

Answer 10

attraction between molecules of different substances

Question 11

define intermolecular forces

Answer 11

> 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

Question 12

list the 6 types of intermolecular forces

Answer 12

1. ion-dipole
2. h bond
3. dipole-dipole
4. ion-induced dipole
5. dipole-induced dipole
6. van der waals (london dispersion)

Question 13

define repulsion

Answer 13

reaction between 2 molecules that forces them apart

Question 14

in order for molecules to interact, the forces must be balances in an __________

Answer 14

energetically favored arranged

Question 15

define energetically favored

Answer 15

> 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

Question 16

define apparent solubility

Answer 16

> the observed solubility, can be affected by kinetic factors
does not change intermolecular forces

Question 17

define supersaturated

Answer 17

a solution that contains greater amounts of solute than needed to form a saturated solution
>greater than equilibrum

Question 18

what is the key to solubility

Answer 18

like dissolves like

Question 19

list the 2 characteristics of a molecule that can interact with water

Answer 19

1. hydrophilic
2. lipophobic

Question 20

list the 2 characteristics of a molecule that cannot interact with water

Answer 20

1. hydrophobic
2. lipophilic

Question 21

list the characteristics of solutes that dissolve in polar solvents

Answer 21

1. salt forms/electrostatic charge
2. hydrophilic groups
3. low molecular weight
4. increased branching

Question 22

list the characteristics of solutes that dissolve in nonpolar solvents

Answer 22

1. non ionizable
2. hydrophobic groups
3. high molecular weight

Question 23

list the 6 main factors impacting solubility

Answer 23

1. IMF
2. solvents
3. salt form
4. solid state/particle size
5. pH/ionization
6. temperature

Question 24

define dipole

Answer 24

results from the unequal sharing of electrons making up a covalent bond

Question 25

explain how water solubilize salts

Answer 25

dissociates them and insulates ion from each other using ion-dipole forces

Question 26

explain how was solubilizes organic molecules

Answer 26

donates and accepts hydrogen bonds

Question 27

how do alcohols work as solvents?

Answer 27

> dissolve non-ionized forms better than salt forms of organic compounds
dipole-dipole or dipole-induced dipole forces

Question 28

list the 4 types of alcohol solvents

Answer 28

1. alcohol or ethanol
2. glycerin
3. proplyene gylcol
4. polyethylene glycol

Question 29

explain how non polar solvents solubilize hydrophobic solutes

Answer 29

induced dipole-induced dipole forces (van der waals)

Question 30

define dielectric constant

Answer 30

as the polarity of a substance is higher, the substance is more polar

Question 31

what is the goal of mixed solvents

Answer 31

to increase the solubility of drugs/solutes by mixing 2 or more solvents

Question 32

define co-solvency

Answer 32

can increase the solubility of drugs/solutes by mixing 2 or more solvents

Question 33

how are mixed solvents and hydrophobic drugs used together

Answer 33

can be used to increase the aqueous solubility of hydrophobic drugs by mixing different polarities

Question 34

how do you calculate dielectric constant of a mixture

Answer 34

multiplying the volume fraction of each solvent times it dielectric constant and adding

Question 35

how are drugs in salt forms solubilized

Answer 35

ion and formal dipole bonding

Question 36

list 3 physical modifications that improve solubility

Answer 36

1. particle size reduction
2. modification of solid state
3. drug dispersions in carriers

Question 37

list the 4 chemical modifications that improve solubility

Answer 37

1. change in pH or buffer
2. prodrug
3. complexation
4. salt formation