Exam 1 - Drug Absorption

Question 1

hydrophilic

Answer 1

compatible with water
* water loving molecules
* carbohydrates and many proteins

Question 2

hydrophobic (lipophilic)

Answer 2

not compatible with water
* water-fearing / fat-loving molecules
* lipids and some proteins

Question 3

passive diffusion

Answer 3

process by which molecules move across a cell membrane from an area of high to low concentration
* lipid soluble
* hydrophobic
* small, uncharged molecules

Question 4

carrier transport

Answer 4

process which specific proteins facilitate the movement of substances across the cell membrane, passively or actively, typically against the concentration gradient

Question 5

Aqueous diffusion

Answer 5

the process by which water-soluble molecules passively move between cells through channels or pores in cell membranes

Question 6

weak organic acid

Answer 6

compound that partially releases H+

Question 7

weak organic base

Answer 7

compound that partially accepts H+

Question 8

HA

Answer 8

non-ionized weak organic acid

Question 9

H+ + A-

Answer 9

ionized anion

Question 10

HB+

Answer 10

ionized cation

Question 11

H+ + B

Answer 11

nonionized weak organic base

Question 12

pH

Answer 12

measure of the amount of hydrogen ions [H+] in a liquid

Question 13

low pH

Answer 13

signifies high acidity

Question 14

high pH

Answer 14

signifies basic

Question 15

Which substituents make drugs behave like weak organic acids?

Answer 15

• -COOH
• -OH

Question 16

Which substituent makes drugs behave like weak organic bases?

Answer 16

• -NH2

Question 17

drug ionization

Answer 17

process by which a drug gains or loses hydrogen ions in solution

Question 18

pH partition hypothesis

Answer 18

• the ionization of a drug is influenced by the pH of the environment it is in
• this affects the drug’s absorption and distribution across biological membranes

Question 19

influx transporters

Answer 19

only transport drugs INTO cells
* OATs (11 distinct proteins)
* OCTs (5 distinct proteins)

Question 20

OATs

Answer 20

organic anion influx transporters
* transport a wide variety of organic acids

Question 21

OCTs

Answer 21

organic cation influx transporters
* transport wide variety of organic bases

Question 22

What are OATs and OCTs are typically called?

Answer 22

• drug influx pumps
• influx pumps

Question 23

efflux transporters

Answer 23

only transport drugs out of cells
* MRPs (7 distinct proteins)

Question 24

Where are transporters distributed?

Answer 24

intestinal cells, kidney cells, liver cells, brain blood vessels

Question 25

What are drug transporters involved in?

Answer 25

* drug absorption * drug excretion * drug uptake and efflux by various cells and tissues

Question 26

What factors affect drug absorption rate from all sites?

Answer 26

* blood flow * surface area of administration site * number of cell layer * drug concentration gradient

Question 27

What are factors affecting drug absorption rates from GI tract?

Answer 27

* gastric emptying time * intestinal transit time * binding to mucus and food -- inhibits absorption * first pass effect

Question 28

In passive diffusion, which form of organic molecules can easily move across the cell membrane?

Answer 28

non-ionized drugs

Question 29

In carrier transport, which form of organic molecules move through carrier proteins?

Answer 29

ionized forms