Pharmacology Flashcards Preview

Z MD1 GI block > Pharmacology > Flashcards

Flashcards in Pharmacology Deck (92)
Loading flashcards...
1

1 drug that is an antacid

magnesium hydroxide

1

where is the chemoreceptor trigger zone

in the medulla, but outside of the BBB

1

forumla to work out the volume of distribution

amount in body/conc in plasma

1

describe the difference in renal excretion and metabolism of drugs of a newborn compared to normal

renal clearance is 20% of adults deficient in phase 2 conjugation therefore increased conc in blood and increased half life

2

what is zero order elimination

you saturate the elimination process at a certain concentration, and therefore with more drug administered.. you get increasing concentration with no steady state achieved

3

drug distribution is driven by what

circulation

3

why is the peak concentration higher in a slow distributing drug with iv administration

because it stays in the blood for longer

3

what are the causes of interpatient variability

age genetic factors idiosyncratic reactions disease drug-drug interaction

4

which drugs are used for motion sickness as well as nausea and vomiting

H1 receptor anatagonists and muscurinic receptor antagonists

4

most drugs are eliminated at a rate that is...

proportional to the conc in plasma

6

2 drugs that are proton pump inhibitors

omeprazole esomeprazole

7

definition of constipation

infrequent defection less than 3x per week, often with straining, with hard, uncomfortable stools

8

side effects of H1 receptor antagonists used for vomiting/nausea

extremely sedative

8

what is the name of the opoid that causes constipation

loperamide

8

what things in the body act as drug reservoirs

plasma proteins cells fat - leads to slow distribution

9

major problem with using CNS D2 anatagonists

can cause extrapyramidal side effects - worst case scenario = tardive dyskinesia

10

action of proton pump inhibitors

decreases gastric acid secretion by inhibiting the proton pump in the parietal cells

10

why are prostaglandin E analogues not regularly used

can induce abortion but increasing the motility of the uterus

11

what are 2 bulking agents used for constipation

bran psyllium

12

major lifestyle factors that lead to constipation

- inadequate dietary fibre - inappropriate fluid intake - inappropriate bowel habits - inadequate activity and exercise - DRUGS - spinal injury - dementia - depression

13

forumla for renal clearance

GFR + TS - TR

15

how do prostaglandin E analogues treat PUD

increased mucous secretion and mucosal blood flow and decreases gastric acid secretion

16

2 major actions of metoclopramide

- anti-emetic - increases gastric motility

16

how do you calculate bioavailability

area under the curve for oral absorption / area under the curve for iv adminstration x 100

17

for a drug with oral absorption with first order elimination, the rate of change of drug in the body is related to

absorption rate and elimination rate

18

what factors affect drug distribution

molecular size - small can cross vascular endothelium ability to bind to plasma proteins - unbound can cross vascular endothelium lipid solubility - can pass into cell membranes

18

when you change first order kinetics of a drug to a log vs time graph - what three things can you calculate

- VD - half life - clearance

19

what is first pass metabolism

metabolism of a drug when it passes through the liver

20

when are the only times that drug-drug interactions are important

when drug B has a narrow therapeutic index conc-response curve to B should be steep

21

what is bioavailability

the proportion of active drug which enters systemic circulation

21

describe the effects of disease on drugs

can effect: - absorption (gastric stasis, malabsorption) - metabolism (liver cirrhosis) - excretion (renal failure)

22

what side effects do prostaglandin E analogues have

- abortion - colic and diarrhoea by stimulating the bowel

22

what are the features of a drug that follows first order kinetics

- rapid rise - drug has half life - peak conc related to dose and volume of distrubtion

23

How do antacids work

neutralise the gastric acid (dont decrease production)

24

what are the features of a drug with first order kinetics using low term iv infusion

- at steady state, the rate of infusion = rate of elimination - concentration at the steady state is proportional to infusion rate - pattern of accumulation reflect multiple dosing

25

what is the difference between metabolism and excretion

metabolism - chemical changes excretion - physical expulsion

27

1 drug that is a prostaglandin E analogue

misoprostol

28

actions of the 3 steps in renal excretion

- glomerular filtration (takes drugs out of blood) - tubular secretion (takes drugs out of blood) - tubular reabsorption (puts drugs back into blood)

29

how do cytoprotective agents treat PUD

coat the ulcer site and therefore heals ulcers by stopping the acid from getting to them

30

drug that is a 5HT3 receptor antagonist

ondansetron

30

action of faecal softeners and lubcricants

detergents - enhance mixture of water into faeces --> makes faeces softer

30

for a first order kinetic drug - what is the formula for the rate of elimination

-KX (K = elimination rate constant, X = amount of drug in body)

32

what do spasmolytics do

blocks muscurinic receptors on the muscle --> stops the increased gut motility - reduces pain associated with ulcers

33

action of H2 receptor antagonists in treating peptic ulcer disease

decrease gastric acid secretion by blocking effects of histamine on parietal cells

34

action of osmotic saline laxatives

slowly absorbed ions which cause osmotic fluid retention --> colonic stimulation by distention due to increased fluid volume

35

1 drug that is a H2 receptor antagonist used for treating PUD

Ranitidine

35

drug that is a faecal softener

docusate

36

describe the difference in renal excretion and metabolism of drugs in the elderly

renal function decreases from age 20 deficient in cytochrome p450 causes increased half life and conc in blood of drug

37

what is the volume of distribution

the volume of body water in which a drug appears to be dissolved in after it has distributed throughout the body

38

2 drugs used as dopamine D2 receptor antagonists

metoclopramide prochlorperazine

39

what is the lipid solubility of acidic and basic drugs in different pHs

low pH - acidic drugs lipid soluble and basic not high pH - acidic drugs not lipid soluble and basic are

40

where is the vomiting centre

in the dorsolateral reticular formation of the floor of the 4th ventricle

41

1 drug that is a H1 receptor antagonists

promethazine

43

receptors that involve the circulating substances stimulating the chemoreceptor trigger zone that stimulates vomiting

D2 receptors and 5HT3 receptors

45

how long is the course of treatment of peptic ulcer disease using proton pump inhibitors

~8 weeks

46

what are pharmacokinetic drug-drug interactions

drug A modifies conc of drug B at its receptor

48

1 drug that is a muscarinic receptor antagonists used for nausea/vomiting/motion sickness

hyoscine hydrobromide

49

difference between phase 1 and phase 2 drug metabolism

1 - creates a chemical functional group on the drug (cytocrome p450) 2 - conjugation of water soluble molecule to the functional group on the drug

51

what are the main classes of drugs used for peptic ulcer disease

- proton pump inhibitors - H2 receptor antagonists - antacids - cytoprotective agents - spasmolytics - Prostaglandin E Analogues

51

side effects of antacids

- constipation/diarrhoea - cause rebound gastric acid secretion - can tend to effect some prescription drugs - systemic drugs can cause alkalosis, kidney damage and worsen existing HT - Mg can cause coma in kids

52

action of stimulant laxatives

precise mode of action not known - may stimulate colonic myenteric nerve plexuses, irritate intestinal mucosa or by direct sensory nerve ending irritation --> increase motility

53

what is the renal clearance

the amount of blood from which drug is removed by the kidneys per time

55

side effects of 5HT3 R anatagonists

very minor - maybe headache and constipation

57

how do bulking agents help for constipation

indigestible vegetable fibres - causes greater faecal water retention --> greater volume of intestinal contents --> increased stimulation of reflex bowel activity

58

what are pharmacodynamic drug-drug interactions

drug A modifies effect of drug B without affecting its conc

59

features of oral administration with first order elimination

- peak no as high as with IV (due to some elimination during absorption

61

drug that is a osmotic saline laxative

magnesium sulphate

63

what is the disadvantage of lipid soluble drugs

high lipid solubility will lead to sequestration in lipid (sit in the fat)

64

all drug elimination depends on

concentration of drug in the blood

66

receptors for motion sickness

muscurinic receptors and H1 receptors

67

how does metoclopramide increase gastric motility

- through acting on 5HT4 --> releases ACh in the nerve plexuses in the gut --> speeds up the movement of the gut - D2 anatagonism --> dis-inhibition

69

what are the 4 types of laxatives

- bulking agents - faecal softeners and lubricants - osmotic laxatives - stimulant laxatives

70

drug metabolism involves

a chemical change to a drug by enzymes making is more water soluble for excretion

71

why do you give a loading dose

if you have a drug with a long half life, it is going to take a long time to reach a steady state concentration. Therefore to get the patient to experience the effect of the drug sooner you give a loading dose

73

where does drug metabolism occur

mostly in the liver

74

what can drug reservoirs do

- prolong action (release from store as conc falls) - can quickly terminate action (if stored drug has high capacity) - can lead to slow distribution (if capacity of store is great)

76

drug that is a neurokinin-1 receptor antagonists

aprepitant

77

3 actions on receptors that metoclopramide does

- D2 antagonist - weak 5HT3 anatagonist - 5HT4 agonist

78

drugs that are stimulant laxatives

bisacodyl Senna

79

what are the maximal values for GFR and renal clearance

GFR = 125 ml/min renal clearance = 800ml/min

80

what is ADME

- administration and absorption - distribution - elimination - metabolism - excretion

81

what are the features of a drug with first order kinetics using short term iv infusion

- rate of accumulation decreases as conc increases - peak not as high as for iv bolus - after infusion over, get elimination only

82

side effect of bulking agents

flatulence

83

what is the major precaution when taking stimulant and osmotic laxatives

pt can become dehyrated and loose electrolytes

84

action of deactivated charcoal

gastrointestinal decontaminant - also used to remove poisons from the GI tract

86

what factors of a drug make it good for local administration

- poorly absorbed - conc so low that if it were to be absorbed - conc will be too low for systemic effect

87

what factors determine the volume of distribution

- if the drug binds to plasma proteins (greater conc in plasma - VD is small) - if the drug binds to tissues/taken up by cells (VD is large)

88

how many half lives does a drug go through when giving multiple doses to get to 99% of the drug conc at a steady state

7 half lives

89

1 drug that is a spasmolytic

hyoscine butylbromide

90

what affects bioavailability

how much drug is absorbed how much drug undergoes first pass hepatic metabolism and local metabolism

91

how does the rebound effect of antacids work

antacids stimulate gastrin release --> need to take more and more antacid to neutralise the excessive stimulation of HCL production by gastrin

92

what is simethicone

agent used for the treatment of flatulence - changes the surface tension of the small air bubbles --> coalescence into big, air bubbles --> easily passed