drug interactions

Question 1

CVS meds (ACE inhibitors, diuretics, beta blockers, digoxin) rely on the function of what

Answer 1

kidney

Question 2

what do NSAIDs do that prevent ACE inhibitors from working? What is the resulting effect?

Answer 2

• NSAIDs block prostaglandins so they block kidney function
• ACE inhibitors rely on kidney function
• BP increases

Question 3

how long does it take for an interaction to occur between NSAIDs and other drugs

Answer 3

7-10 days

Question 4

does high or low dose of methotrexate interact with NSAIDS

Answer 4

high dose interacts; low does not

Question 5

interaction between acetominophen and NSAIDs is good or bad?

Answer 5

good

Question 6

interaction between misoprostol and NSAIDs is good or bad?

Answer 6

good

Question 7

what is misoprostol used to treat

Answer 7

ulcers and gastric bleeding

Question 8

can you take misoprostol if you want to get pregnant

Answer 8

no. it causes abortion

Question 9

name 5 drugs with a low therapeutic index

Answer 9

• lithium
• digoxin
• carbamazepine
• warfarin
• cyclosporine

Question 10

what are the 4 pharmacodynamic effects that can occur with drug interactions

Answer 10

• antagonism
• unexpected drug effect
• summation
• synergism/potentiation

Question 11

antagonism

Answer 11

reduction of drug response by one or both drugs

Question 12

unexpected drug effect

Answer 12

combination of drugs gives response not observed when given individual drug

Question 13

summation

Answer 13

both drugs show their effects

Question 14

synergism/potentiation

Answer 14

drugs show GREATER effect than each individually

Question 15

why is epi given with LA

Answer 15

constrict blood bc LA causes dilation

Question 16

name 5 things than interact with epi

Answer 16

• beta blockers
• tricycle antidepressants (TCA)
• GA
• cocaine
• amphetamines

Question 17

what happens if you are taking beta blockers and you get epi

Answer 17

• beta blockers prevent vasodilation of b.v. of skeletal m (beta 2)
• vasoconstriction still happens with alpha 1
• vasoconstriction with no vasodilation => increase BP

Question 18

what happens if you are taking TCA and you get epi

Answer 18

• increase HR and BP

- abnormal heart rhythm

Question 19

what happens if you are taking cocaine and amphetamines and you get epi

Answer 19

• increase BP
• may lead to cardiac arrhythmia
• toxicity

Question 20

what happens if you are taking GA and you get epi

Answer 20

-cardiac arrythmia

Question 21

how does omeprazole affect absorption

Answer 21

• its a proton pump inhibitor and changes GI pH

- affects ionization of another drug in stomach => ionized is harder to absorb

Question 22

how can tetracycline absorption get affected

Answer 22

chelation of tetracycline with calcium or iron ions slow absorption

Question 23

metoclopramide increases gastric motility. how does this affect absorption?

Answer 23

earlier and higher peak concentrations

Question 24

opioids decrease gastric motility. how does this affect absorption?

Answer 24

slower, later, and lower peak concentrations

Question 25

how does taking Abx chronically affect absorption

Answer 25

changes bowel bacteria which help with absorption

Question 26

if Abx wipe out bowel bacteria, which drug would have an issue getting absorbed

Answer 26

digoxin

Question 27

displacement phenomenon

Answer 27

if 2 drugs have the affinity for the binding site, the one with greater affinity will displace the other

Question 28

main enzymes for metabolism in the liver

Answer 28

CYP P450

Question 29

what happens if drug A induces CYP for drug B

Answer 29

B gets metabolised => less effectiveness

Question 30

what happens if drug A inhibits CYP for drug B

Answer 30

B increases in body => OD or toxic effects

Question 31

what does rifampin do to warfarin

Answer 31

rifampin is an inducer => more enzymes => more warfarin gets metabolised => low INR decreases

Question 32

what does ketoconazole do to warfarin

Answer 32

ketoconazole is an inhibitor => less enzymes => more warfarin available => high INR

Question 33

low INR means

Answer 33

coagulation, clots, stroke

Question 34

high INR means

Answer 34

high bleeding

Question 35

what does st johns wort do to cyclosporine A

Answer 35

it induces 34A and 1A2 => cyclosporine is metabolised

Question 36

what does st johns wort do to crixivan

Answer 36

lowers its levels to ineffective levels

Question 37

what does grapefruit do to CYP3A4

Answer 37

inhibits CYP 34A

Question 38

is enzyme inhibition fast or slow? why

Answer 38

fast; may be binding competitively

Question 39

is enzyme induction fast or slow? why

Answer 39

slow; involves protein synthesis

Question 40

pt is on a prodrug. what happens if they take an inducer

Answer 40

INCREASE of the drug

Question 41

pt is on a prodrug. what happens if they take an inhibitor

Answer 41

DECREASE of the drug

Question 42

codeine is considered a "prodrug" because it gets metabolized by 2D6 to morphine. why do some people not feel like "codeine is working"?

Answer 42

genetic variability of amount of 2D6. so if little, codeine doesnt go to morphine (so no affect)

Question 43

in tubular secretion, drugs compete for transport to secretion. how might this be useful?

Answer 43

drug A prevents drug B from secretion to maintain conc of B in the body

Question 44

name 2 deliberate drug interactions that are beneficial

Answer 44

- misoprolol and NSAID | - probenacid and penicillin