Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

PHAR300 > L21 Drug Interactions > Flashcards

L21 Drug Interactions Flashcards

1
Q

How many drugs do hospitalized patients usually receive? What are they given for

A

More than 20

anxiety, blood pressure, infection, pain, anesthetics

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

The relationship between the number of drugs taken and the number of patients experiencing side effects is…

A

linear

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

TF: Drug interactions always decrease therapeutic effects of a drug

A

False, interactions can increase or decrease therapeutic or toxic effects of a drug

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

TF: There is a link between poverty and the increase of adverse effects due to drug interactions

A

True

This is due to lack of professional advice/monitoring and the tendency to seek out cheaper alternatives

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Roasted coffee is a mixture of _ bioactive compounds

A

> 1000

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

The _ in red wine sometimes triggers headaches in certain people

A

tyramine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

When do drug-drug interactions occur (4)

A
  1. multiple drugs to treat one disorder
  2. Multiple disorders requiring different drugs e.g. chronic conditions + acute infection
  3. OTC meds, caffeine, nicotine, alcohol
  4. Elderly patients have high incidence of drug interactions due to amount of medications they take and their age related changes in drug clearance
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are factors that lead to drug interaction (5)

A
  • Lack of info about what the patient is consuming
  • inadequate checking by prescriber or pharmacist
  • Individual variation in pharmacokinetics
  • Variation in time of day when drugs are consumed
  • failure to monitor patient response/failure of patient to report adverse symptoms, or misdiagnosis of a drug reaction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are some factors that can influence outcomes of drug interactions

A

patient factors: genetic variation, current diseases, diet, environment, smoking, alcohol, illegal drug use

drug administration: dose, duration, sequence, timing of consumption, route of administration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

TF: drug interactions are usually external

A

False, interactions are rare for topical medications

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Drug interactions can be… (4)

A

additive (1+1=2)
synergistic (1+1=3)
potentiation (1+0=2)
antagonism (1+0=0.5)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe what pharmacokinetic drug interactions are. What are the consequences of such interactions

A

they are interactions that occur when one drug alters the absorption, distribution, metabolic, or excretion of another drug (ADME)

The drug is closer to toxicity or further from efficacy in the context of therapeutic index and window

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe what pharmacodynamic drug interactions are

A

they are interactions that occur when two drugs act on the same site
drug A can affect the action of drug B through competition or blockage (alteration of effects)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Which better describes pharmacokinetics:

alter blood concentration of a given drug
or
modulate drug effect at given plasma concentration

A

alter blood concentration of a given drug

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Which better describes pharmacodynamics:

alter blood concentration of a given drug
or
modulate drug effect at given plasma concentration

A

modulate drug effect at given plasma concentration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the main site of absorption for oral drugs?

A

GIT

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How does gastric pH alter drug absorption?

A

weak acids are better absorbed at acidic pH as they will be unionized and lipid soluble

thus, drugs that can alter gastric pH may have an effect on drug absorption

e.g. asprin is a weak acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

TF: milk helps the absorption of tetracycline (antibiotic)

A

False, the calcium carbonate in milk or in antacid binds to tetracycline which can no longer be absorbed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Calcium carbonate inhibits _ absorption

A

thyroxine (forms a drug complex in intestine)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

thyroxine absorption is inhibited by _

A

calcium carbonate (forms a drug complex in intestine)

*tums (thyroxine = T4, thyroid hormone)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What happens if you take calcium carbonate and thyroxine at the same time?

A

hypothyroidism and increased TSH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are some agents that are used to stabilize gastric pH?

A

H2 blockers, proton-pump inhibitors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Altering the gastric pH can reduce the absorption of which anti fungal drug?

A

ketoconazole

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How can diarrhea affect drug absorption?

A

The drug passes through the SI so quickly that it is not absorbed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

TF: drugs that affect the absorptive surface are can cause drug interaction

A

False, although diseases that affect absorptive surface area can cause drug interaction, there are no drugs that cause this

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What are P-glycoproteins?

A

efflux pumps that actively transport drugs Out of the enterocyte and into the lumen of the intestine (protective mechanism)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Where can P-glycoproteins be found?

A

intestine, kidneys, blood-brain barrier, tumour cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

TF: P-glycoproteins interact with select chemical structures only

A

False, they interact with a wide variety of chemical structures (promiscuous)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

_ of p-glycoproteins in tumour cells are in involved with drug resistance

A

upregulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What happens when a drug is ejected from the enterocyte by p-glycoproteins?

A

it is excreted in the feces

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Drug A which induces p-glycoproteins would have what effect on drug B?

A

upregulation of p-glycoproteins > decreased absorption and bioavailability of drug B

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

TF: weak bases are better absorbed in highly acidic environments

A

True, since it will be in its un-ionized form

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

TF: weak acids are better absorbed in highly acidic environments

A

True (since they are in their unionized form)

*weak acid form depends on its environment unlike strong acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

How fast the drug gets into the intestine will depend on…

A

the rate of gastric emptying

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Once in the blood, drugs get to the liver through…

A

the portal vein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

TF: Once absorbed, drugs circulate freely in the blood to bind to tissue receptors

A

False, there is an equilibrium between free drugs and drugs bound to plasma proteins

only the free drugs can bind to tissue receptors

37
Q

Distribution of a drug can be altered by drugs that…

A

compete for binding sites on plasma protein

This changes the concentration of free drug circulating in the blood

38
Q

TF: interactions based on distribution and binding are common and dangerous

A

false, they are rare (but yes, can be dangerous)

39
Q

What is the largest and most important group of enzymes that metabolize drugs?

A

cytochrome p450 family of enzymes

40
Q

cytochrome p450s are mostly found where?

A

liver

41
Q

what are isozymes

A

different forms of an enzyme that catalyze the same chemical reaction but have distinct structural or genetic characteristics

42
Q

Which CYP450 enzymes are very important for drug metabolism?

A

CYP2D6: antidepressants (e.g., fluoxetine, paroxetine), antipsychotics (e.g., haloperidol), beta-blockers (e.g., metoprolol), and opioids (e.g., codeine, tramadol)
CYP3A4: statins (e.g., simvastatin), immunosuppressants (e.g., cyclosporine), antivirals (e.g., ritonavir), and some opioids (e.g., fentanyl)

and CYP2C19, CYP2C9, CYP1A2

43
Q

TF: CYP450 enzymes can be down regulated by inflammation

A

True

44
Q

How many alleles does CYP2D6 have?

A

70 alleles

45
Q

Why do people who lack CYP26D not respond to codeine for pain relief

A

CYP2D6 activity is necessary to convert codeine to morphine

46
Q

Why do people who lack CYP2D6 not respond to tamoxifen (breast cancer drug)

A

CYP2D6 activity is necessary to convert tamoxifen to its active form

47
Q

Classify the following as antidepressants, antipsychotics, beta-blockers, and opioids:

fluoxetine, paroxetine, metoprolol, haloperidol, tramadol, codeine

A

antidepressants: fluoxetine, paroxetine
antipsychotics: haloperidol
beta-blockers: metoprolol
opioids: codeine, tramadol

48
Q

how many alleles does CYP34A have

A

4

49
Q

What is ketoconazole

A

an antifungal (-ole) that is metabolized by many CYP450 enzymes (including CYP2D6 and CYP3A4)

it is also a powerful inhibitor of some CYP enzymes such as CYP3A4

50
Q

Which drug or food inhibits CYP3A4? What are the consequences of this

A

ketoconazole and grapefruit juice, affects metabolism of calcium channel blockers, benzodiazepines, HIV protease inhibitors and more (any drug that is metabolized by CYP3A4)

blocking CYP3A4 can also cause statin toxicity (increased statin levels in blood) an myopathy

ketoconazole:antifungal

51
Q

How can enzyme inhibition increase the amount of drug?

A

by decreasing the drug clearance

52
Q

TF: CYP450 enzyme induction leads to decreased drug availability

A

True,

if drug A induces p450s, drug B will have lower bioavailability thus decreasing its therapeutic effect

53
Q

TF: A competitive inhibitor will have a lower Km but the same Vmax

A

False, competitive = higher Km, same Vmax

unless it binds irreversibly, then Vmax would decrease, Km would increas

54
Q

TF: A non-competitive inhibitor will have the same Km but lower Vmax

A

True

55
Q

TF: During enzyme induction, Km will be higher while Vmax stays the same

A

False

the expression and activity of enzymes are increased in response to the presence of specific substances, often substrates or inducers. Therefore:

enzyme induction = same Km, higher Vmax (increased enzyme activity)

Vmax: rate of reaction (higher = faster)

Km: substrate affinity

56
Q

Why should you not smoke tobacco while taking blood pressure meds or depression meds

A

tobacco metabolizes CYP1A2, an enzyme that breaks down drugs for blood pressure and depression

57
Q

Why does ethanol increase risk of acetaminophen toxicity

A

ethanol induces a CYP450 enzyme and depletes glutathione. Thus, the body is unable to metabolize and detoxify acetaminophen

58
Q

Why do antibiotics impair oral contraceptive efficacy

A

GI flora is altered by antibiotics thus altering enterohepatic estrogen recycling (decrease half-life)

it may also increase liver inactivation of the estrogen in oral contraceptives

59
Q

What kinds of drugs should not be taken when relying on oral contraceptives?

A

antibiotics, anticonvulsants, anti-infectives

60
Q

What do PM, EM, and URM stand for

A

PM: poor metabolizers
EM: efficient metabolizers
URM: ultra-rapid metabolizers

61
Q

which CYP450 enzyme does St-John’s wort induce? why is this dangerous

A

CYP3A4

can cause rapid metabolism of life-saving drugs, which can be lethal
or
increase the activity of a drug if it is activated by CYP34A leading to overdose

62
Q

garlic supplements decrease _ levels

A

saquinavir (inverse) 51% decrease

this is a HIV protease inhibitor, so garlic supplements pose a serious risk for individuals taking meds for HIV/AIDS

63
Q

What bioactive agent does grapefruit contain that might inhibit CYP3A4 (and CYP1A2)

A

furanocoumarins
such as naringin and naringenin

64
Q

TF: Grapefruit juice can increase drug absorption of statins and caffeine

A

True

65
Q

What effect does grapefruit juice have on p-glycoproteins

A

it enhances the function of p-glycoproteins thus leading to decreased intestinal absorption, lower penetration of BBB and increased renal excretion

66
Q

What are the effects of grapefruit juice on metabolism and absorption

A

metabolism: inhibits CYP3A4 (which breaks down statin) up to 3 days
absorption: stimulates p-glycoproteins thus decreasing absorption

67
Q

Which CYP450 does THC act on? Does it induce or inhibit it?

A

THC is a CYP1A2 inducer

68
Q

Which CYP450 does CBD act on? Does it induce or inhibit it?

A

CBD is a CYP3A4 inhibitor

69
Q

TF: Cannabis is safe to take with other drugs

A

False, it may potentially affect metabolism of drug resulting in potentially dangerous drug interactions

THC - CYP1A2 inducer
CBD - CYP3A4 inhibitor

70
Q

What is warfarin and what is it used for

A

it is an anticoagulant used in exceptional cases as it has a very small therapeutic index

71
Q

What are some potential drug interactions with warfarin

A

ethanol and aspirin

warfarin + aspirin = potentiation

72
Q

TF: When a patient stops taking an enzyme inhibitor or inducer after long duration of use, a rebound and opposite effect can occur

A

True

73
Q

TF: Discontinuation of enzyme-inducing drug is equivalent to adding enzyme inhibitor

A

True

74
Q

TF: Discontinuation of enzyme-inhibiting drug will have no after effects

A

False, it will be the equivalent to adding enzyme-inducer

75
Q

What is a new way to study drug interactions

A

high-throughput robotics allow to predict potential drug interactions and toxic metabolites

76
Q

What does drug reabsorption depend on (for renal clearance)?

A

whether the drug is lipid-soluble and on the pH of the proximal tubule

77
Q

Renal clearance of lithium can be decreased by … (2)

A

diuretics and NSAIDS

dangerous since lithium has low safety factor

For diuretics: since lithium shares transport mechanisms with sodium, increased sodium reabsorption can lead to decreased lithium excretion.

outerwhise, diuretics usually increase renal clearance

78
Q

Drugs that alter _ can lead to changes in tubular reabsorption and thus excretion

A

urinary pH

79
Q

Which two drugs can compete and lead to toxic levels of methotrexate in the bloodstream

A

amoxicillin and methotrexate

80
Q

TF: Pharmacodynamic interaction alter the dose-response curve left or right by involving the action of drug at the receptor site

A

False, it alters the curve up or down, not left or right

81
Q

In which region of the brain is there a defect in dopamine for individuals suffering from Parkinson’s disease

A

substantia nigra

82
Q

What is the current therapy for PD? How does it work

A

Levodopa (dopamine precursor) which is converted to dopamine by dopa decarboxylase

levodopa must penetrate BBB to reach substantial nigra (where dopamine is required)

It is given in combination with Carbidopa which blocks the peripheral dopa decarboxylase and cannot cross the BBB. This way, more levodopa is available to enter the brain

> Levodopa + Carbidopa

83
Q

Individuals who take NSAIDs (e.g. aspirin) regularly also take which drugs to counter NSAID side effects such as ulcers?

A

aspiring + proton pump inhibitor

84
Q

TF: Drug interactions can be beneficial

A

True

85
Q

Why don’t aspirin and ibuprofen mix well?

A

ibuprofen will prevent aspirin activity therefore ibuprofen must be taken after aspirin has taken effect

*note aspirin must be taken in low doses to prevent infarcts so increasing aspiring dosage is not a good idea

86
Q

Opioids should not be taken with…

A

CNS depressants

leads to respiratory arrest

87
Q

CNS depressants should not be taken with…

A

opioids

leads to respiratory arrest

88
Q

What foods should not be taken with MAOIs (antidepressants, monoamine oxidase inhibitors)

A

wine and cheese

both contain tyramine which releases neurotransmitters in the synapse

taking both would flood adrenergic terminals in the brain and periphery with noradrenaline which can lead to hypertensive crisis (increase B) which can cause a stroke

PHAR300 (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions