Ch. 6-Drug Absorption

Question 0

How long is the small intestine?

Answer 0

20-23 ft (6-7 m)

Question 1

what is the most important part of the GI tract for drug absorption?

Answer 1

small intestine

Question 2

How long is the large intestine?

Answer 2

5 ft (1.5 m)

Question 3

systemic administration

Answer 3

absorbed directly from site of administration into bloodstream and spreads to site of action

Question 4

nonsystemic administration

Answer 4

drug is localized to the area and not intended to spread

-not always successful, sometimes drug spreads anyway and causes side effects

Question 5

where is a drug absorbed that is taken orally?

Answer 5

small intestine

Question 6

villi

Answer 6

line the intestine, they increase surface area for drug absorption

Question 7

which route is most common and patient preferred?

Answer 7

oral route

Question 8

drug absorbed by:

4 ways

Answer 8

1. passive diffusion (primary)
2. carrier mediated (fastest)
3. intestinal drug efflux (spits drug out of cell, limits absorption)
4. transcytosis (receptor mediated, inefficient)

Question 9

4 classes of drugs

Answer 9

Class 1-high solubility and permeability (best)
Class 2-low solubility and high permeability
Class 3-high solubility and low permeability
Class 4-low solubility and permeability (worst)

Question 10

normal stomach pH

Answer 10

1.0-3.5

Question 11

parts of small intestine

Answer 11

duodenum, jejunum, and ileum

Question 12

normal duodenum pH

Answer 12

5.5-6.5

Question 13

duodenum

Answer 13

first part of small intestine, receives stomach contents

Question 14

normal jejunum pH

Answer 14

6.5-7.0

Question 15

jejunum

Answer 15

2nd part of small intestine, about 40% of the small intestine total

Question 16

normal ileum pH

Answer 16

7.0-7.5

Question 17

ileum

Answer 17

last part of small intestine (end), about 60% of total small intestine

Question 18

why does the pH raise after leaving the stomach?

Answer 18

the stomach is very acidic, and after the contents leave the stomach they are neutralized by the pancreas, so the pH gets closer and closer to 7

Question 19

Drug properties that make oral administration impossible

Answer 19

• drug is an irritant
• drug has poor lipophilicity (can’t passively diffuse)
• large molecular size (can’t passively diffuse)

Question 20

Patient properties that make oral administration impossible

Answer 20

• unable/unwilling to swallow meds
• patient needs more immediate response
• GI distress or disease
• they are taking meds that are incompatible with the drug

Question 21

parenteral route

Answer 21

given somewhere other than the GI tract

-ex) subcutaneous, intravenous, intramuscular

Question 22

rectal route

Answer 22

among slowest absorption, reserved for situations where oral administration is impossible

Question 23

local administration

Answer 23

nonsystemic, usually blood absorption doesn’t occur

-lower doses can be used

Question 24

local parenteral delivery

Answer 24

injecting the drug near the site of action

-ex) intracardiac, intrathecal (cerebrospinal fluid), intralumbar