Exam 2

Question 1

T or F: Only drugs that are dissolved in their free molecule form in the body will be readily absorbed.

Answer 1

True. Drugs in their full particle form will not be readily absorbed

Question 2

What is a nonelectrolyte?

Answer 2

Drug that is fully unionized/ uncharged. Examples include mannitol, glucose, and more.

Question 3

T or F: A non-electrolyte solution with water will conduct electricity better than water alone.

Answer 3

False. They will both conduct electricity equally. Neither is better.

Question 4

A high partition coefficient means the drug is more _________.

Answer 4

Lipophilic

Question 5

A low partition coefficient means that drug is more __________

Answer 5

Hydrophilic (polar)

Question 6

T or F: For all different types of soluble drugs, the ratio of oil and water solubility is approximately equal to the oil/water partition coeffincent.

Answer 6

False. This is only true if the solubility is not very high for the drug.

Question 7

What two factor govern passive diffusion of drugs across biological membranes?

Answer 7

Oil solubility (Soil)
Molecular size/weight

Question 8

T or F: The solubility of a drug in oil can be found by taking the rearranging the partition coefficient equation.

Answer 8

True. Soil can be found by multiplying Ko/w and Sw

Question 9

T or F: Oil solubility can be estimated for high lipophilic drugs forming ideal or nearly deal solutions in an oil environment.

Answer 9

False. It can be estimated for moderately lipophilic drugs.

Question 10

What are the 3 properties associated with ideal solutions?

Answer 10

• Volume of solution is equal to the sum of the individual components
• No heat is released is absorbed when components are mixed
• Components mix randomly in solution

Question 11

T or F: If a drug is liquid at room temperature it has a high solubility.

Answer 11

False. If liquid at room temperature, the solubility is miscible as it is so high.

Question 12

What is this equation used for?

Answer 12

This equation is used to determine the solubility of a solid drug at room temperature in oil using its mole fraction.

Question 13

If the melting point is below 25C for this equation, then the solubility of the a solid drug in oil at room temperature is __________.

Answer 13

Miscible

Question 14

For every ______C increase in melting point above room temperature, the mole fraction solubility in oil of an ideal solute falls by a factor of _______.

Answer 14

100C
10

Question 15

T or F: Drugs with very high melting points that are placed in oil will have decrease solubility.

Answer 15

True!

Question 16

Which one has miscible solubility in oil?

Answer 16

Benzene ring as it is a liquid at 25C because its melting point is 5.5C. Drugs that are liquid at room temperature have miscible solubility in oil. X2b=1

Question 17

Which one is not miscible in oil at room temperature?

Answer 17

Naphthalene as it is a solid at room temperature meaning it will be soluble in oil.

Question 18

T or F: For every 100C increase in MP above room temperature, solubility of a drug in oil and in water fall by a factor of 10.

Answer 18

True! This is true in both oil and water solubilty.

Question 19

For every increase in logKo/w of ________ unit, water solubility of a drug falls by a factor of ________.

Answer 19

1 unit
10

Question 20

What is the general solubility equation used to determine the solubility of a drug in water at room temperature?

Answer 20

Question 21

Indomethacin is an NSAID with a MW of 385, mp if 159C, and a LogKo/w of 4.27. Estimate its water solubility in g? at 25C.

Question 22

What is the effect of melting point of a drug on it solubility?

A. At mp >25C, higher mp leads to higher solubility
B. At mp >25C, higher mp leads to lower solubility
C. At all mps, higher mp leads to higher solubility
D. At all mps, higher mp leads to lower solubility

Answer 22

B. At mp >25C, higher mp leads to lower solubility

Question 23

What is the effect of drug lipophilicity on its aqueous solubility?

A. Higher octanol/water partition coefficient leads to higher aqueous solubility
B. High octanol/water partition coefficient leads to lower aqueous solubility
C. Octanol/water partition coefficient is unrelated to lipophilicity
D. Lipophilicity has no effect on aqueous solubility.

Answer 23

B. High octanol/water partition coefficient leads to lower aqueous solubility

Question 24

Which of these compounds would be expected to have a higher solubility in lipid membrane/oil?

Answer 24

They hame similar solubilities in oil. This is known through using the solubility in oil equation which only takes melting point into account. As the melting points are so similar, they have similar solubilities.

Question 25

Which of these compounds would be expected to have a higher solubility in water?

Answer 25

Hydrocortisone as it has a lower logKo/w compared to estradiol. Remember that every 1 unit increase in logKo/w decreases water solubility by a factor of 10.

Question 26

What is a cosolevent?

Answer 26

This is a solvent added to the primary solvent at a smaller quantity than the primary solvent to increase the solubility of a compound in the primary solvent.

Question 27

What are 3 common cosolvents used in pharmacy practice?

Answer 27

Ethanol, glycerin, and propylene glycol

Question 28

Why are ethanol, glycerin, and propylene glycol often used a cosolvennts?

Answer 28

They are polar but much less polar than water and can substantially increase the solubility of organic compounds.

Question 29

T or F: In most cases, we want drugs that are less polar than either solvents.

Answer 29

True. Normally we want non-polar drugs so they are less polar than the solvents. When this is the case, the solubility graph with a cosolvents looks like the image.

Question 30

What does it mean for a drug to be non-polar?

Answer 30

It means it is less polar than the solvents it is in.

Question 31

For non polar solutes, the solubility ____________ strongly with __________ fraction of cosolvent.

Answer 31

Increases Increasing

Question 32

T or F: Polar and semi-polar drugs behave the same way as non polar drugs in the sense that increasing the fraction of cosolvents increases the solubility.

Answer 32

False. Only non-polar molecules have that relationship with cosolvents.

Question 33

What is the approximate effect of melting point of a drug on its solubility? A. 10x decrease per 100C increase B. 4x decrease per 100C increase C. 10x decrease per 10C increase D. 4x decrease per 10C increase

Answer 33

A. 10X decrease per 100C increase

Question 34

Which of the following factors affect the solubility of a moderately lipophilic drug in oil (assuming that the liquid drug is miscible with oil)? A. Melting point B. Low Ko/w C. Both

Answer 34

A. Melting point

Question 35

What is the approximate effect of logKo/w of a drug on its aqueous solubility? A. 10x decrease per 1 unit of logKo/w increase B. 10x increase per 1 unit of logKo/w increase C. 10x decrease per 10x logKo/w increase D. 10x increase per 10x logKo/w increase

Answer 35

A. 10x decrease in solubility per 1 unit LogKo/w increase

Question 36

What is Kw?

Answer 36

Ionization of water with the value of 1x10^-14 at room temperature. It does change at different temperatures.

Question 37

What is the relationship between drug solubility and volume fraction of cosolvent for a drug that is less polar than the cosolvent in water? A. Linear relationship of increasing solubility with increasing volume fraction of cosolvent B. Linear relationship of decreasing solubility with increase volume fraction of cosolvent C. Log-linear relationship of increasing solubility with increasing volume fraction of cosolvent D. Log-linear relationship of decreasing solubility with increasing volume fraction of cosolvent

Answer 37

C. Log-linear relationship of increasing solubility with increasing volume fraction of cosolvent

Question 38

At room temperature, the equilibrium constant for water, Kw, is what?

Answer 38

1 x 10^-14, giving it pKw to be 14

Question 39

If a molecule with its pKa is given and added to water, will you be able to tell if the water becomes more acidic or basic?

Answer 39

No. You need to know if the drug is in its acid form or conjugate base/salt form.

Question 40

The higher the ionic strength means the more __________ that is shield the effects of charges.

Answer 40

Ions

Question 41

_______ __________ is important to colloid stability

Answer 41

Ionic strength

Question 42

In order to calculate an accurate pH value, one must use both _________ and ________ coefficent.

Answer 42

Concentration Activity coefficient

Question 43

If you put valproic acid (pKa=4.8) in water, what happens to the pH of the water?

Answer 43

It decreases

Question 44

If you put divalproex sodium into water (salt form of valproic acid), what happens to the pH of the water?

Answer 44

It increases because the salt form is also the conjugate base form.

Question 45

Is morphine a weak acid or base?

Answer 45

Weak base. The morphine hydrochloride is the conjugate acid form which correlates to pKa being 7.87.

Question 46

Is atropine a weak acid or base?

Answer 46

Atropine is a weak base. It conjugate acid/salt form is atropine sulfate which has the pKa of 9.65.

Question 47

If more ions (higher ionic strength) are present, the interactions with the drug to the counter ion will be _______ strong.

Answer 47

Less

Question 48

If there are less ions (lower ionic strength), the interactions with the drug to the counter ion will be _______ strong.

Answer 48

More

Question 49

T or F: Ionic strength increases with the concentration of the ions.

Answer 49

True

Question 50

T or F: Ionic strength increases with the number of charges on the ions.

Answer 50

True

Question 51

What is the key formulation variable affecting the stability of gels, emulsions, and suspensions?

Answer 51

Ionic strength

Question 52

Emulsions and suspensions are often stabilized by _________ _________.

Answer 52

Electrostatic Repulsion

Question 53

If you decrease ionic strength, the stability of the compound will ___________.

Answer 53

Increase

Question 54

If you increase ionic strength, the stability of the compound will __________.

Answer 54

Decrease

Question 55

What two things affect gel making?

Answer 55

Ionic strength and pH

Question 56

T or F: If you have a high ionic strength in the gel, then it will be less stable.

Answer 56

True. This means the repulsions are less and the gel is less stable.

Question 57

Which of the following solutions would have the highest ionic strength? Consider both protons on H2SO4 to be strong acids. A. 0.1M K2SO4 B. 0.1M KHSO4 C. 0.1M H2SO4 (equivalent to 0.2M Na H2SO4) D. 0.1M Na2SO4 E. All solutions have similar ionic strength

Answer 57

E. All solutions have similar ionic strength (all have same number of anions and cations as well as molar concentration which is what goes into ionic strength)

Question 58

Phosphoric acid is a weak acid with pKa values of 2.12, 7.21, and 12.67. Given this information, which of the following solutions would have the highest ionic strength? A. 0.1M K3PO4 B. 0.1M K2HPO4 C. 0.1M KH2PO4 D. 0.1M H3PO4 E. All solutions have equal ionic strength

Answer 58

A. 0.1M K3PO4 (dissociates into 3 K+ and 1 PO4^-3)