Drug Absorption #3

Question 1

pH partition theory is related to

Answer 1

absorption

Question 2

What is the assumption of the pH partition theory

Answer 2

the membrane that molecule would have to cross are lipid and because of that the unionized form is more lipid soluble–> leading to it being absorbed

Question 3

Acidic drugs would be most unionized in the ____, while basic drugs would be better absorbed in the ______

Answer 3

stomach; intestine

Question 4

_______ form are not absorbed

Answer 4

ionized

Question 5

T/F The Surface area of the intestine WAS taken into consideration for the pH partition theory

Answer 5

FALSE: WAS NOT

Question 6

T/F For a drug undergoing passive diffusion, movement of drug across the membrane stops when drug concentration on both sides of the membrane becomes equal

Answer 6

FALSE
o Drug movement across the membrane does not stop when the concentration is equal on both sides
o No net gain or loss of drug on either side of the membrane
o The drug is at equilibrium
o Movement in both directions is equal

Question 7

Passive diffusion is driven by ______

Answer 7

kinetic energy

Question 8

Which of the following would decrease when a drug is more rapidly absorbed?

a) AUC
b) Efficacy
c) Cmax
d) Potency
e) Tmax

Answer 8

e) Tmax

Question 9

The relationship between _____, _____, and _____ are directly related

Answer 9

• partition coefficient
• lipid solubility
• rate of absorption

Question 10

The absorption rate ______ as the lipid solubility is increasing

Answer 10

increases

Question 11

Lipophilic groups have better absorption, what mechanism do they use?

Answer 11

passive diffusion

Question 12

Hydrophilic groups all essentially have the same absorption, what mechanism do they use?

Answer 12

carrier mediated or paracellular

Question 13

T/F There are fewer pores/channels in the ileum compared the jejunum so absorption is lower

Answer 13

TRUE

Question 14

An experiment that would allow us to distinguish between carrier mediated vs. diffusion. (3)

Answer 14

an experiment that depends on

• energy
• inhibits the carrier
• saturation occurs

Question 15

Prodrugs are _______–>_____-

Answer 15

inactive, the body changes the prodrug to its active form

Question 16

What are the reasons as to why prodrugs are developed? (6)

Answer 16

• poor absorption
• poor solubility
• instability
• poor distribution
• poor taste
• pain on injection

Question 17

Weak Acids have…

Answer 17

a higher absorption at lower pH (more unionized form)

Question 18

Absorption of ____ is very slow

Answer 18

ions

Question 19

The addition of an -O functional group makes the drug more _____ soluble–>

Answer 19

lipid ; has a higher absorption

Question 20

The rate of ____ can effect the amount of drug that is actually absorbed

Answer 20

dissolution

Question 21

The AUC for large particles is typically smaller…why?

Answer 21

b/c the drug must first go into solution–> large particles take longer to go into solution

Question 22

T/F A drug administered as an oral solution would be expected to be completely absorbed from the GI tract

Answer 22

FALSE

• Could precipitate in stomach/intestine
• Decomposition could occur in stomach/intestine
• First-pass metabolism
• If transporter required, saturation and/or competition is possible

Question 23

T/ F Polar drugs would primarily be absorbed from the SI by transcellular route

Answer 23

FALSE

• generally move by paracellular transport
• polar compounds would not easily cross through lipophilic membrane

Question 24

dissolution

Answer 24

a process; how solid gets turned into a solution

Question 25

Particle size effects _____ and _____

Answer 25

dissolution and absorption

Question 26

_____ is more water soluble

Answer 26

ionized

Question 27

more ionized form Acid dissolve more at _____ pH Base dissolve more at ____ pH

Answer 27

higher; lower

Question 28

Ketoconazole is a weak ______. Which means that it is less soluble at a higher pH

Answer 28

base

Question 29

Why is the salt form of a drug usually administered?

Answer 29

because the salt form is more soluble

Question 30

Salt form vs. Free Form

Answer 30

Faster RATE and EXTENT of absorption in the salt form (shorter Tmax and higher AUC)

Question 31

T/F pH of the environment HAS an effect on the dissolution rate of the salt form

Answer 31

FALSE: DOES NOT HAVE

Question 32

______ change pH in microenvironment around dissolving particle

Answer 32

excipients

Question 33

polymorphism

Answer 33

the ability of a molecule to exist in more than one crystalline state

Question 34

T/F Only one form of the polymorphic state is stable

Answer 34

TRUE; overtime the unstable will convert to the stable form (beta form)

Question 35

metastable form

Answer 35

if conversion rate is SLOW

Question 36

Which form has the greatest solubility? | Stable or Unstable

Answer 36

Unstable (smaller AUC)

Question 37

Do we always want RAPID dissolution?

Answer 37

NO. Not for drugs that are extended release, blood pressure or glucose medications

Question 38

What would be the expected rate limiting step in the absorption process for a solid poorly soluble and highly permeable drug? a) dissolution b) diffusion c) blood flow

Answer 38

dissolution

Question 39

amorphous state (2)

Answer 39

- molecules are arranged in the solid form RANDOMLY | - higher solubility--> higher absorption

Question 40

crystalline state

Answer 40

-molecules are arranged in a more STRUCTURED form

Question 41

The bioavailability of various drug products can be evaluated by comparing their plasma conc.-time curves. The 3 most important parameters of comparison obtained directly from the curves are A. biologic half life, absorption rate constant, AUC B. Time of peak concentration (tmax), absorption rate constant, elimination rate constant C. maximum drug concentration, time of peak concentration (tmax), duration of action D. AUC, time of peak concentration (tmax), maximum drug concentration E. rate of elimination, AUC, rate of absorption

Answer 41

D. AUC, time of peak concentration (tmax), maximum drug concentration tells us something about RATE and EXTENT of absorption

Question 42

solvate

Answer 42

the solvent is trapped within the solid crystal

Question 43

hydrate (2)

Answer 43

- water | - less soluble in water than the anhydrous form

Question 44

Generally, the greater the degree of solvation the _______ the solubility in a medium that is the same as solvate molecules

Answer 44

LOWER

Question 45

_____ form is more soluble in water

Answer 45

anhydrous

Question 46

Ampicillin TriHYDRATE would be ____ solubility than anhydrous form

Answer 46

SLOWER