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NAPLEX 21 > Drug interactions > Flashcards

Drug interactions Flashcards

1
Q

refers to the effect or change that a drug has on the body

A

pharmacodynamics

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2
Q

what kind of interaction occurs when two or more drugs are given together?

A

PD drug interaction

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3
Q

Additive vs synergism?

A

additive = drugs that have similar end effects through different mechanisms/receptors

synergism = effect from two drugs taken in combo is greater than the effect from simply adding the two individual effect together

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4
Q

drugs with polyvalent cations or other binding properties should be separated from what drugs?

A

quinolones
tetracyclines
levothyroxine
oral bisphosphonates

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5
Q

What drugs require an acidic pH environment (ie interaction with PPIs)

A

antifungals

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6
Q

The majority of PK drug interactions occur where?

A

during metabolism in the liver

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7
Q

Who should not use codeine?

A

Ultra rapid metabolizers of 2D6 due to toxic levels of morphine

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8
Q

inhibitors or inducers?

decrease enzyme function and the ability to metabolize compounds

A

inhibitors

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9
Q

drugs that are substrates for the same CYP enzyme will have a/n inc/dec rate of drug metabolism and a/n increased/decreased serum drug level

A

dec metabolism

inc drug level

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10
Q

with prodrugs, the opposite happens with in inhibitor… what happens?

A

the active drug concentration decreases with an inhibitor (needs to be converted to active form by metabolism!)

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11
Q

What are major CYP inhibitors?

A

G PACMAN

G- grapefruit

P- protease inhibitors (esp ritonavir)

A- azole antifungals (fluconazole, itraconazole, keto, posa, vori, isavuconazonium)

C- cyclosporin, cimetidine, cobistat

M- macrlides (clarithromycin, erythromycin, but NOT azithromycin)

A- amiodarone (and dronedarone)

N- non-DHP CCBs (diltiazem and verapamil)

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12
Q

What effect do major CYP inhibitors have on substrates?

A

deceased metabolism = increased serum concentrations

INhibitors= INcreased effects

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13
Q

CYP inhibitors effect on prodrugs

A

decreased conversion to active drug, dec levels

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14
Q

What is the effect of inducers?

A

increase enzyme production/activity

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15
Q

what is the effect of inducers on substrates?

A

drugs that are substrates for the same CYP will have an increased rate of drug metabolism and a decreased serum drug level

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16
Q

More or less drug lost with inhibitors in first pass?

A

less

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17
Q

More or less drug lost with inducers in first pass?

A

more

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18
Q

what is the effect of an inducer on a prodrug?

A

increases effect!

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19
Q

what are the major CYP inducers?

A

PS CORPS

Phenytoin

St. John’s Wort

Carbamazepine (also an auto-inducer)

Oxcarbazempine (and eslicarbazepine)

Rifampin (and rifabutin, rifapentine)

Phenobarbital

Smoking

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20
Q

What effect do inducers have on substrates?

A

increased metabolism

decreased serum concentrations and decreased effect

inDucers = Decreased effects

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21
Q

Inhibitors vs inducers… time for enzyme action?

A

inhibitors = FAST!!!

inducers = “lag” time –> full effect on drug levels may not be seen for up to 4 weeks, when inducer is stopped could take 2-4 weeks for induction effects to disappear completely

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22
Q

when a drug inhibits Pgp pump, a drug that is a Pgp substrate will have inc/dec absorption

inc or dec level of drug?

A

increased absorption, substrate drug level will increase

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23
Q

What are some common Pgp substrates?

A

CHICA

Anticoagulants (apixaban, ribaroxaban)
Cardiovasular drugs (digoxin, diltiazem, verapamil)
Immunosuppressants (cyclosporin, tacrolimus)
HCV drugs (ombitasvir, paritaprevir, dasabuvir)
Colchicine

24
Q

Pgp inducers?

A

PS CPR

phenytoin
st johns wort

carbamazepine
phenobarbital
rifampin

25
Q

Pgp inhibitors?

A

CVAD

amiodarone,
diltiazem
verapamil)
cyclosporin

26
Q

enterohepatic recycling inc or dec duration of action?

A

increases

27
Q

describe enterohepatic recycling locations

A

metabolized in liver

transports back through the bile back to the gut

from the gut, reabsorbed in small intestine

enter portal vein

travel back to liver

28
Q

What is the effect of amiodarone + warfarin?

A

INC WARFARIN LEVELS = DEC WARFARIN DOSE by 30-50%

amiodarone inhibits 2C9, which metabolizes warfarin

dec warfarin metabolism = inc INR = inc bleeding

29
Q

what is the effect of amiodarone + digoxin?

A

DEC DIGOXIN DOSE BY 50%

amiodarone inhibits Pgp; digoxin is a substrate of Pgp

dec digoxin excretion = inc toxicity… risk of bradycardia

30
Q

What is the effect of digoxin + loop?

A

DIGOXIN TOXICITY

loops decrease K, Mg, Ca, Na

Low K, Mg or Ca will worsen arrhythmias

31
Q

What are drugs that decrease heart rate and have additive effects?

A

amiodarone

digoxin

BB

clonidine

32
Q

What is the effect of statins + strong CYP3A4 inhibitors

GPACMAN

A

INC levels of Cyp3a4 substrates: lovastatin, simvastatin, atorvastatin

simva and lova are contraindicated

33
Q

What is the effect of warfarin + 2C9 inhibitors & inducers?

A

inhibitors = INC levels of warfarin = INC INR

inducers = dec levels of warfarin = dec INR

34
Q

What are some 2c9 inhibitors?

A

BAMA increases warfarin

azoles, Bactrim, amiodarone, metronidazole

35
Q

what are some 2c9 inducers?

A

decrease warfarin

rifampin, st johns wort

36
Q

What is the effect of 3a4 inhibitors + 3a4 substrates?

A

decrease 3a4 metabolism = inc drug levels = inc toxicity

*do NOT use a 3a4 inhibitor with an opioid metabolized by 3a4

grapefruit = do not use with 3a4 substrates

37
Q

What drugs cannot be taken with grapefruit?

A

SLANT

amiodarone, simvastatin, lovastatin, nefidipine, tacrolimus

38
Q

what opioids are 3a4 substrates?

A

fentanyl
hydrocodone
oxycodone
methadone

39
Q

what is the effect of valproate + lamotrigine?

A

INC LEVELS OF LAMOTRAGINE (skin reactions!!)

valproate decreases lamotrigine metabolism

40
Q

blocking MAO will inc or dec epi, NE, DA, and 5Ht?

A

increase! (epi, NE, DA hypertensive crisis) 5ht= SS

reason for washout period; fluoxetine - 5 weeks

41
Q

What are drugs that will increase serotonin?

A

SSRis, SNRIs, TCAs, MAOi, mirtazapine, trazodone,

fentanyl, methadone, tramadol

buspirone, delsym, LITHIUM, st johns wort

triptans

linezolid

42
Q

MAO inhibitors + tyramine rich foods will cause?

A

hypertensive crisis

do not eat aged cheese, air dried meats, sauerkraut

43
Q

2d6 inhibitors + 2d6 substrates?

A

dec drug metabolism = toxicity

avoid use or dec dose of substrate

44
Q

examples of 2d6 inhibitors?

A

F FAP

amiodarone
fluoxetine
paroxetine
fluvoxamine

45
Q

3a4 or Pgp inhibitors

+

calcineurin inhibitors (tacrolimus, cyclosporine)

or

mTOR kinase inhibitors (sirolimus, everolimus)

A

decrease drug metabolism = inc toxicity

avoid use together or decrease dose of CNI, mTOR

46
Q

what is a common drug that can decrease drug levels of phenytoin, phenobarbital, primidone, carbamazepine/oxcarbamazpine

A

oral contraceptives… loss of seizure control

47
Q

smoking (inducer 1a2) +

some antipsychotics, antidepressants, hypnotics, anxiolytics, caffeine, theophylline, warfarin (r-isomer)

A

smokers who quit: drug concentrations will increase

current smoker: decrease levels

48
Q

Bleeding risk drugs?

A

anticoagulants

antiplatelets

NSAIDs

SSRi, SNRIs

garlic, ginger, ginkgo, ginseng, glucosamine

Vitamin E

willow bark

fish oils (high mg)

49
Q

what can cause high K?

A

spironolactone, eplerenone - highest risk

ACE, ARBs, entresto

amiloride, triamterene, KCl, tacrolimus, cyclosporin, canagliflozin, bactrim, drospirenone OC

50
Q

QT prolongation drugs?

A

amiodarone (DOC in arrhythmia for HF), dofetlide, sotalol,

quinolones/macrolides

azoles

TCAs, SSRI (escitalopram 20/10mg and citalopram 40/20mg)>, mirtazapine, trazodone, SNRI

haloperidol, ziprasodone

antiemetics

donepezil, fingolamid, methadone

51
Q

What drugs cause ototoxicity?

A

AG

cisplatin

loops

salicylates

vancomycin

52
Q

what drugs cause nephrotoxicity?

A

AG, ampho B, polymyxins, vancomycin

cisplatin (use amifostine to protect kidneys)

cyclosporine, tacrolimus

loops

NSAIDs

radiographic contrast dye

53
Q

PDE-5 inhibitors should start with a lower dose when used in combo with either of these 3 drug classes

A

3a4 inhibitors

nitrates

alpha-1 blockers

54
Q

what drugs can cause anticholinergic toxicity?

A

paroxetine, TCA, FGA

sedating antihistamines

atropine, dicyclomine, meclisine

benztropine

baclofen, carisodolol, cyclobenzaprine

oxybutinin, tolterodine

55
Q

fentanyl, hydrocodone, methadone, oxycodone

apixaban, rivaroxaban, R-warfarin

amlodipine

cycloposporin, tacrolimus, sirolimus

atorvastatin, lovastatin, simvastatin

avanafil, sildenafil, tadalafil, vardenafil

ethinyl estradiol

what cyp?

A

3a4 substrate

56
Q

carbamazpine, oxcarbamazpine, phenobarbitol, phenytoin, rifampin, smoking, st John wort

A

3a4 inducers

57
Q

clarithromycin, erythromycin, azoles

amiodarone, diltiazem, verapamil

cobicstat, protease inhibitors, ritonavir

cyclosporine, grapefruit

A

3a4 inhibitors

NAPLEX 21 (60 decks)

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