Solubility

Question 1

What is solubility?

Answer 1

Concentration of a solute when the solvent has dissolved all that solute that it can at a given temperature.

Question 2

What is solubility in reference to equilibrium?

Answer 2

Concentration of solute in a saturated solution at equilibrium.

Question 3

What type of property is solubility?

Answer 3

Physical property

Question 4

Miscible meaning.

Answer 4

Refers to a solute when it is a liquid. This solute can form a solution with a solvent over any concentration range.

Question 5

What are the factors affecting solubility?

Answer 5

Temperature = principal factor
Pressure = unimportant in pharm. applications
Polarity (and hydrogen bonding)
Particle size

Question 6

What is NOT a factor of solubility?

Answer 6

How fast a substance dissolves

Question 7

What is heat of solution?

Answer 7

Overall energy exchange when a solute dissolves in a solvent

Question 8

What is lattice energy?

Answer 8

energy released when one mole of ionic solid is formed from gaseous ions

Question 9

What is heat of hydration?

Answer 9

Enthalpy change associated with dissolution of one mole of ion in water

Question 10

Heat of solution equation.

Answer 10

∆Hsolution= ∆Hsolute + ∆Hhydration

∆Hsolute - always endo

Question 11

What are the steps of solution formation?

Answer 11

1. separation of solute particles
2. separation of solvent particles
3. mixing of solute and solvent particles.

Question 12

Describe the separation of solute part. steps.

Answer 12

Attractive forces between solute part. are cleaved with energy

Question 13

Describe the separation of solvent part. steps.

Answer 13

Attractive forces between solvent part. are cleaved with energy

endothermic

Question 14

Describe the mixing of solute and solvent part.

Answer 14

solute and solvent particles create bonds which releases energy

exothermic

Question 15

What is Hess’s law?

Answer 15

net enthalpy change is sum of the enthalphy change in each step

Question 16

Relationship between boiling point and solubility.

Answer 16

higher melting point = lower solubility

Question 17

Cis E isomer vs Trans Z isomer

Answer 17

Cis e isomer is more soluble
Cis e has lower melting points

Question 18

Describe the solubility of strong electrolytes in water.

Answer 18

soluble

Question 19

Describe the solubility of weak electrolytes in water.

Answer 19

often not soluble

Question 20

Describe the solubility of non electrolytes in water.

Answer 20

little to no solubility.

Question 21

What is dissolution?

Answer 21

The process by which solid solute enters into a solution in the presence of a solvent.

Question 22

List the basis of dissolution.

Answer 22

diffusion layer model
noyes-whitney relationship
hixson-crowell cube-root relationship

Question 23

What is the diffusion layer model?

Answer 23

Concentration gradient between concentration of the drug in the diffusion layer (Cs) and concentration of the drug in the bulk medium (Cb)

(Cs-Cb)

Question 24

Describe the noyes-whitney relationship.

Answer 24

Amount of drug dissolved from solid particles in a function of time (Quantitative Analysis)

Question 25

Describe the Hixson-crowell cube-root relationship.

Answer 25

The decrease in the size of particles changes the effective area.

Question 26

Name of apparatus 1.

Answer 26

rotating basket

Question 27

Assemblt of apparatus 1.

Answer 27

cylindrical, stainless steel basket shaft assembly

Question 28

Use of apparatus 1.

Answer 28

capsules suppositories tablets with low density/dissolve very slowly

Question 29

Name of apparatus 2

Answer 29

paddle

Question 30

assembly of apparatus 2

Answer 30

paddle and shaft assembly

Question 31

use of apparatus 2

Answer 31

formulations that sink but does not touch the bottom

Question 32

List the factors affecting drug dissolution.

Answer 32

Physicochemical properties of the drug formulation factors physiologic factors

Question 33

What are the factors under physicochemical properties?

Answer 33

ionized and unionzed forms particle size crystalline state

Question 34

Explain how ionized and unionized forms of drugs affect dissolution?

Answer 34

ionized form = more water soluble = faster dissolution

Question 35

Unionized vs ionized: absorption

Answer 35

Unionized drug forms results in more efficient absorption

Question 36

Explain how crystalline state of drugs affect dissolution.

Answer 36

weakly bound amorphous and metastable forms are dissolve faster

Question 37

What increases rate of dissolution in solid dosage forms?

Answer 37

disintegration disaggregation

Question 38

How does viscosity affect dissolution?

Answer 38

increased viscosity = dissolution rate decreases

Question 39

How does change in crystalline structure affect dissolution?

Answer 39

Change in the crystalline structure of the drug particles in aged suspensions = dissolution rate decreases

Question 40

What factor affects dissolution rate of semi solid forms?

Answer 40

type of base used

Question 41

What is the normal GET?

Answer 41

15 mins to 2 hours

Question 42

Explain the variation in GET.

Answer 42

fasted state - faster fed state - slower

Question 43

List the formulation factors affecting dissolution.

Answer 43

solid dosage forms suspensions and emulsions semisolid dosage forms

Question 44

List the physiologic affecting dissolution.

Answer 44

gastric emptying time intestinal transit time variability of pH

Question 45

State the partition law

Answer 45

A solute will distribute itself between two immiscible solvents so that the ratio of its concentration in each solvent is equal to the ratio of its solubility in each one.

Question 46

What is the partition coefficient?

Answer 46

Measure of a drug concentration in a nonpolar organic phase to that in a polar aqueous phase

Question 47

What is the partition orientation of strong electrolytes?

Answer 47

completely dissociated in aqueous solutions.

Question 48

What is the partition orientation of nonelectrolytes?

Answer 48

dissociates in both aqueous and organic solvents

Question 49

What is the partition orientation of weak electrolytes?

Answer 49

orientation depends on pH of solution

Question 50

How does increasing unsaturation affect solubility?

Answer 50

Increase solubility in polar solvent

Question 51

Dissolution profile of a drug can be used in the formulation the drug for maximum [?]

Answer 51

bioavailability

Question 52

[?] of a drug can be used in the formulation the drug for maximum bioavailability

Answer 52

dissolution profile

Question 53

What is dieelectric properties?

Answer 53

ability to store charge.

Question 54

pH of stomach

Answer 54

1-3 pH

Question 55

pH of intestine

Answer 55

pH 5-7