Drug Absorption #2 Flashcards Preview

Pharmaceutics Spring 2016 > Drug Absorption #2 > Flashcards

Flashcards in Drug Absorption #2 Deck (94)
1

T/F Passive diffusion is uni-directional

FALSE: can move in either direction (the concentration gradient determines which direction the molecule moves)

2

What are the 2 routes in which blood can diffuse?

intracellular(transcellular)
-paracellular

3

intracellular transport

molecules move directly through the membrane
-this is the most common

4

paracellular transport

molecules move between cells
-has a limiting factor (size of the molecules)

5

What is the limiting factor of paracellular transport?

the size of the molecule

6

T/F Carriers are typically proteins

TRUE

7

What are the 2 types of carrier mediated transport?

-facilitated
-active

8

Carrier Mediated Transport (2)

-are specific (only move one type of molecule)
-typically located in specific areas of the GI tract

9

T/F Carriers CAN NOT be saturated

FALSE; there are only a certain number of carriers, which means they can be saturated

10

T/F Carriers can be inhibited

TRUE

11

T/F Carrier transport is one direction

TRUE (mucosal side --> to the blood)

12

Which transport system requires ATP energy?why?

Active transport b/c it can occur from a region of lower concentration to higher concentration

13

metabolism

chemical altering of the drug molecule by the body

14

What is the effect of metabolites on bioavailability?

although metabolites are inactive--> they decrease bioavailbility because there would be a reduced amount of drug that would get to the site of action

15

efflux transporters (2)

-going in the opposite direction than what we would like
-typically P glycoproteins

16

P glycoproteins (3)

-energy driven
-pump the drug back in the direction in which it came from
-not as specific as carrier proteins

17

_____ are thought to cause tolerance to cancer therapeutic agents

P glycoproteins

18

What would be the effect of P glycoproteins on the bioavailability of the drug?

it would DECREASE the bioavailability because its taking the drug molecules in the opposite direction than we want them to go--> not allowing them to ultimately get to the site of action

19

What part of the stomach is where most secretion occurs?

the middle of the stomach

20

Antrum

holds material in the stomach to control how it moves to the pylorus

21

T/F The stomach is very muscular

TRUE

22

What are the functions of the stomach? (4)

-reservoir
-site of the beginning of digestion
-regulate the delivery of nutrients
-bacteriostatic

23

The secretion of ____ typically destroys the bacteria that make it to the stomach

HCl

24

What are the secretion cells in the stomach? (4)

-mucoid cells
-chief cells
-parietal cells
-g cells

25

mucoid cells

secrete mucus

26

mucus provides ____ and ____ protection

chemical and physical

27

chief cells

secrete pepsinogen (gets converted to pepsin)

28

____ begins the digestion process in the stomach

pepsin

29

parietal cells

secrete primarily HCl and intrinsic factors

30

intrinsic factors are necessary for...

absorption of B12

31

G cells

secrete gastrin (which in turn controls the secretion of HCl)

32

About ___L/day of fluids are secreted by the stomach

3

33

Would you anticipate significant absorption from the stomach? Why?

-no, almost no drug is absorbed by the stomach
-drugs do not stay in the stomach long enough and the stomach has a small surface area

34

Where is the site of most absorption of drug?

small intestine due to the large membrane surface area

35

What is the pH of the stomach? with food?

~ 1-2
food neutralizes the stomach--> pH goes up to around 4,5, or 6

36

What are the 3 segments of the small intestine?

-duodenum: connected to the pylorus (upper)
-jejunum (middle)
-illeum (lower)

37

T/F Each segment of the small intestine have regional differences

TRUE. transporter proteins are located at specific sites in the intestine

38

What components help tribute to the large surface area of the small intestine?

-folds of kerckring (increase 3x)
-villi (increase 30x)
-microvill (increase 600x)

39

Bile:
Is stored in the _______; made by the _____

gall bladder; liver
gall bladder empties bile into the duodenum (ph ~6)

40

Why does the pH change from 2 when it leaves the stomach and go up to 6?

bicarbonate ion-->neutralize acidic fluid that is emptying from the stomach

41

What is the primary function of the large intestine? pH?

storage of waste; pH 5.5-7

42

T/F There are vili present in the Large Intestine.

FALSE; no villi present leading to absorption being poorer

43

_____ are present in the large intestine. What is a downfall of having this there?

microflora--> if a drug makes it to the large intestine it may destroy the bacteria that is already there and the bacteria could absorb the drug and metabolize it

44

As pH varies from a weak acid or base... so does

the degree of ionization

45

Summary of pH in GI tract
-stomach (fasting)
-stomach (fed)
-duodenum
-ileum
-large intestine

-stomach (fasting): less than 2
-stomach (fed): 2-6
-duodenum: 6-6.5
-ileum: 7-8
-large intestine: 5.5-7

46

T/F Solids and liquids are emptied the same way from the stomach

FALSE; emptied differently

47

What do you think is a major factor affecting stomach emptying?

food

48

Fed mode of the stomach (3)

-one type of pattern
-regular, frequent contractions
-grinding and mixing occurs as long as food is present

49

_____ and ___ will empty from the stomach and leave in a FIRST order process

liquids and particles less than about 5-10 mm

50

Liquids empty the stomach _____. High Volume--> _____

immediately; faster emptying

51

_____ leave in a ZERO order process, it is converted at a ______ rate

solids; constant

52

What are the 4 phases of the fasting mode in the stomach?

I: relaxation
II: increase in tone and activity (few contraction of different magnitudes)
III: strong contractions--> HOUSEKEEPER
IV: decline in activity

53

The housekeeping stage of the fasting mode....

sweeps anything left in the stomach out

54

How long does it take for material to move through the entire small intestine?

3-4 hours

55

T/F Solution, pellets, and single units move through the small intestine at about the same rate

TRUE-> it does not depend on the presence of food

56

Absorption _____ occur in the stomach--> but the ____ of emptying of the stomach does effect drug absorption

DOES NOT; RATE

57

What factors affect gastric emptying? (11)

-meal type
-hydrogen ion concentration
-volume
-osmolality
-emotional state
-exercise
-posture
-age
-gender
-disease state
-drug

58

Fats, proteins, and carbs typically have _____ emptying if they are the same caloric value. The presence of these _____ emptying

same; decrease

59

____ (food) have the greatest effect on emptying on a molar basis

fats: they are harder to digest

60

hydrogen ion concentration:
_____ concentration in intestine will INHIBIT emptying

Increased

61

Volume:
____ volume of liquid results in more RAPID emptying

increased; liquids in general empty very fast. they can empty even when there is food in the stomach (takes about 12-15 minutes)

62

Osmolality:
_____ contents empty FASTER than _____ liquids

iso-osmotic; hyper-osmotic

63

T/F There are receptors in the duodenum that detect increases in the osmotic pressure that use feedback mechanism

TRUE

64

_____ increases osmotic pressure

eating/food

65

Emotional state:
_______: increases gastric emptying
_______: decreases gastric emptying

aggression- increase
stress, anxiety- decrease

66

Exercise:
________: have no effect or slight increase in gastric emptying
_________: decrease gastric empyting

moderate intensity; vigorous

67

Posture:
If you are on your ____ side: increase gastric emptying
If you are on your _____ side: decrease gastric emptying

right;left

68

T/F Gastric emptying is FASTER in older people

FALSE: SLOWER

69

T/F Females have slower gastric emptying then males

TRUE

70

What disease states INCREASE gastric emptying? (3)

-hyperthyroidism
-duodenal ulcers
-cholecystitis (inflammation of the gallbladder)

71

Gastritis, GERD, Gastric Carcinoma, Pyloric stenosis, Gastric Ulcers, Diabetic Gastroparesis, Hypothyroidism, Migraine, Pregnancy_______ gastric emptying

decrease

72

What drugs DECREASE gastric emptying? (4)

-narcotic analgesic
-isoniazid--> used to treat TB
-antacids
-tricyclic antidepressants

73

What drugs INCREASE gastric emptying? (2)

-metoclopramide
-erythromycin

74

T/F Food has a great impact on gastric emptying

TRUE: general you would want a patient to take solid dosage form on an empty stomach with a full glass of water

75

Why do we want to get the drug out of the stomach ASAP?

because it is not being absorbed in the stomach and it needs to get in the intestine

76

What is considered an empty stomach with food?

-30 minutes before a meal
-2 hours after a meal

77

Why do some drugs need to be taken with food? (2)

-if drug is irritating
-food increase absorption of some drugs

78

T/F You CAN NOT decrease saturation if given with food

FALSE: you can

79

How could food affect absorption of a drug? (3)

-emptying
-change in pH
-interact with drug

80

Food ____ gastric emptying

slows

81

Food changing the pH could do what?

-increase/decrease absorption
-increase/decrease degradation

82

When the drug Nitrofurantoin was given with food, more excretion (unchanged drug) occurred. Why?

When you give with food emptying is SLOWED making the drug stay in the stomach longer which allows more of the drug to dissolve in the stomach before it is emptied into the intestine

83

T/F Blood flow is static.

FALSE: there is first blood flow through the membrane then the drug is being carried away by the blood

84

rate limiting step

slowest step in the overall process that controls how fast the process will proceed

85

perfusion rate limited (2)

-blood flow step is the slowest step (#2)
-drug freely passes through the membrane with little resistance
ex. water and ethanol

86

diffusion or permeability rate limited

-difficult to cross the membrane, slowly crosses the membrane
ex.ribitol (large polar molecule)

87

When a drug is administered through the muscle (IM), then it only has to cross.....

the blood capillaries

88

Capillary walls are very ______ compared to the GI tract. What type of rate limited is this?

permeable
-molecules with HIGH molar weights easily cross the capillary wall
-perfusion rate limited

89

Would you expect gentamicin, a large polar water soluble molecule to be absorbed well?

NO, because it is big and its polar but if administered into muscle tissue it is readily absorbed

90

The vascularity in the SQ tissue is less than that of muscle tissue, what would you expect to be the effect on absorption?

SQ would have a slower rate of absorption because of less blood flow

91

SQ administration: What would be the expected effect on the absorption rate following SQ administration in the following situation?

Application of heat or massage the site of administration

INCREASE because blood flow is increasing

92

o SQ administration: What would be the expected effect on the absorption rate following SQ administration in the following situation?

Co-administration of a vasodilator or hyaluronidase (destroy connective tissue)

INCREASE, vasodilator because blood flow is increasing

hyaluronidase will cause the drug to spread out (increasing the SA)

93

o SQ administration: What would be the expected effect on the absorption rate following SQ administration in the following situation?

Co administration of epinephrine that produces vasoconstriction

DECREASE

94

Feedback mechanism in the duodenum (3)

-receptors located in the duodenum, but control emptying in the stomach
-an increase hydronium ions cause SLOW rate of emptying
-osmotic pressure is related to colligative properties