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Ultimate Sadness > Chapter 3: Drug Interactions > Flashcards

Chapter 3: Drug Interactions Flashcards

1
Q

Definition: pharmacodyamics

A

effect or change that a drug has on the body

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2
Q

Definition: pharmacodynamic drug interactions

A

when 2+ drugs are given together and their end effects impact each other

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3
Q

concurrent benzo + opioid risk

A
  • sedation
  • respratory depression
  • coma
  • death
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4
Q

Definition: synergistic effects

A
  • when two drugs taken in combo have a greater effect than simply adding the 2
  • different from additive effects which is when drugs have similar end effects (?)
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5
Q

Definition: pharmacokinetic

A

effect or change that the ody has on the drug

Absorption
Distribution
Metabolism
Excretion

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6
Q

Definition: chelation

A

when a drug binds to polyvalent cations in another compound → resulting complex cannot dissolve in gut fluid → will pass in stool

e.g. quinolone abx with dairy products

Drugs with polyvalent cations or other binding properties (antacid, Ca, Mg, etc.) should be separated form quinolones, tetracyclines, levothyroxine and PO bisphosphonates

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7
Q

_ is a drug that inhibits the metabolism of darunavir and subsequently increases darunavir levels

A

ritonavir

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8
Q

what is the primary route of drug excretion

A

renal

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9
Q

_ blocks the renal excretion of penicillin

can be beneficial if high [ ] of penicillin is needed

A

probenecid

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10
Q

consequences of salicylate overdose and how to treat

A

toxicity → tinnitus, metabolic acidosis

IV sodium barcarb alkalinizes urine → salicylate ionizes → more hydrophilic → stay in urine → less reabsorbed, more excreted

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11
Q

CYP450 enzymes are primarily expressed in which organ

A

liver

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12
Q

Definition: prodrug

A

inactive form of drug that is taken by patient and converted/metabolized into the active form

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13
Q

benefit of pro drugs

A
  • increased F
  • prevet drug abuse (lisdexamphetamine is inactive and pharmaceutical effect is not experienced when snorting)
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14
Q

capecitabine is a prodrug of _

A

5-FU

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15
Q

clopidogrel is a prodrug of _

A

lol, its active metabolites, just know clopidogrel is a prodrug

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16
Q

codeine is a prodrug of _

A

morphine

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17
Q

colistimethate is a prodrug of _

A

colistin

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18
Q

cortisone is a prodrug of _

A

cortisol

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19
Q

famiciclovir is a prodrug of _

A

peniciclovir

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20
Q

fosphenytoin is a prodrug of _

A

phenytoin

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21
Q

isavuconazonium sulfate is a prodrug of _

A

itraconazole

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22
Q

Levodopa is a prodrug of _

A

dopamine

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23
Q

lisdexamphetamine is a prodrug of _

A

dextroamphetamine

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24
Q

prednisone is a prodrug of _

A

prednisolone

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25
Q

primidone is a prodrug of _

A

phenobarbital

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26
Q

tramadol is a prodrug of _

A

lol, its active metabolites, just know it’s a prodrug

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27
Q

valacyclovir is a prodrug of _

A

acyclovir

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28
Q

valganciclovir is a prodrug of _

A

ganiciclovir

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29
Q

codeine pharmacogenomics consideratios

A

CYP2D6

  • ultrarapid metabolizers covert it to morphine really fast: avoid dt tox
  • poor metaboliers won’t really get to the morphine: avoid dt lack of efficacy
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30
Q

pharmacogenomic considerations with enzyme N-acetyltransferase

A

NAT is highly polymorphic → higher interpatient variability

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31
Q

clopidogrel pharmacogenomics considerations

A

CYP2C19

  • poor metabolizers can’t convert it to active form
  • and on a similar note, avoid with CYP2C19 inhibitors
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32
Q

examples of phase II enzymes

A
  • UGT (urindine diphsphate glucuronosyltransferase)
  • NAT (N-acetyltransferase)
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33
Q

CYP inhibitors (increase/decrease) ability to metabolize compounds

A

decrease → drugs that are substrates for that enzyme have decreased metabolism → increased serum levels and less drug lost to first-pass metabolism

opposite is true with prodrugs

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34
Q

common CYP inhibitors involved in drug interactions

A

G-PACMAN

  • grapfruit
  • protease inhibitors (i.e. ritonavir)
  • azole antifungals (fluconazole, itraconazole and it’s prodrug, ketoconazole, posaconazole, and voriconazole)
  • cyclosporine, cobicistat
  • macrolides (clarithromycin and erythromycin but NOT azithromycin)
  • amiodarone and dronaderone
  • non-DHP CCB (dilt and verapamil)
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35
Q

CYP inducers (increase/decrease) ability to metabolize compounds

A

increase → increased rate of metabolism of drug → decreased serum level and more drug lost to first pass metabolism

full effect on drug levels may take up to 4 weeks to see, and when the inducer is stopped can take 2-4 weeks for effect to disappear

36
Q

common inducers involved in drug interactiosn

A

PS PORCS

phenytoin
soking
phenobarbital
oxcarbazepine
rifampin, rifabutin, rifapentine
carbamazepine
st. john’s wort

37
Q

P-gp physiologic purpose

A
  • efflux pumps
  • protect against foregin substnaces by moving them out of the cell
  • found in many tissue membranes; in GI they pump things into the gut to be excreted in stool
38
Q

P-gp inhibitor effect

A

inhibit P-gp (efflux pump) →drug that is a P-gp substrate isn’t pumped out → increased absorption → drug level increase

39
Q

P-gp common substrates

A
  • anticoagulation: apixaban, rivaroxaban
  • CV drugs: digoxin, dilt, verapamil
  • HCV drugs: sofosbuvir
  • immunosuppressants: cyclosporine, tacrolimus
  • others: colchicine
40
Q

common P-gp inducers

A
  • carbamazepine
  • phenobarbital
  • phenytoin
  • rifampin
  • st. john’s wokrt
41
Q

common P-gp inhibitors

A
  • antiinfectives: clarithromycin, itraconazole, posaconazole
  • CV drugs: amiodarone, dilt, verapamil
  • HCV drugs: ledipasvir
  • HIV drugs: cobicistat, ritonavir
  • others: cyclosporine
42
Q

Definition: enterhepatic recycling

A

after drug has been metabolized by liver, it is transported through the bile back to the gut → drug reabsorbed in small intestine → enter portal vein → travel back to liver → increase duratiion of action

43
Q

amiodarone-warfarin DDI

A

amiodarone inhibits CYP2C9 → decreased metabolism of more potent isomer of warfarin → increased warfarin → increased INR → increased bleed risk

  • if pt was already on amio and you are starting warfarin, start at a warfarin dose < 5
  • if pt already on warfarin and starting amio, decrease current warfarin dose by 30-50% based on INR
  • monitor INR regularly
44
Q

amiodarone-digoxin DDI

A
  • amiodarone inhibits P-gp (efflux pump) → decreased digoxin efflux → increased digoxin [ ] → increasd digoxin ADR and toxicity
  • both amio and digoxin decrease HR → incraesed risk of bradycardia

  • if pt on amio and now starting digoxin, start dig at low dose (0.125)
  • if pt on dig and now starting aio, decrease existing dig dose by 50%
  • avoid dig if possible
  • monitor HR, avoid other HR lowering drugs (beta-blockers, clonidine, dilt, verapamil)
  • monitor for dig tox (N/V, vision change)
45
Q

digoxin-loop diuretic DDI

A
  • loop diuretics decrease K, Mg, Ca, Na → increased risk/worsening of arrhythmias AND increased risk of dig tox with low K and Mg
  • renal impairment (can be exacerbated by loops) → increased dig levels and to

  • monitor electrolytes
  • if renal impairment, decrease dig dose, frequency, or dc
46
Q

statins-CYP3A4 inhibitors DDI

A
  • CYP3A4 substrate statins: atorvastatin, lovastatin, simvastatin
  • CYP3A4 inhibitors inhibit CYP3A4 → decreased metabolism of affected statins → increased levels → increased myopathy risk (if bad enough can cause rhabdo with renal failrue)

  • simvastatin and lovastatin contraindicated iwth strong CYP3A4 inhibtors
  • switch to non-CYP3A4 substrate statins: pitavastatin, pravastatin, rosuvastatin
47
Q

warfarin - CYP2C9 inhibitors and inducers DDI

A
  • CYP2C9 inhibitors → decreased warfarin metabolism → increased levels fo warfarin → increased INR and bleed risk
  • CYP2C9 inducers → increased warfarin metabolism → decreased INR and increased clot risk

monitor INR, goal of 2-3 for most patients (2.5-3.5 in pts with high risk indications such as mechanical mitral valve)

48
Q

drugs that specifically include istructions to not take with grapefruit

A
  • amiodarone
  • simvastatin
  • lovsatatin
  • nifedpine
  • tacrolimus

other drugs carry risk, but don’t explicity spell out grapefruit

49
Q

opioids that are metabolized by CYP3A4

A
  • oxycodone
  • fentanyl
  • hydrocodone
  • methadone

do NOT use with CYP3A4 inhibitor: increasd [ ] of opioids → increased ADR (sedation, fatal)

50
Q

valproate-lamotrigine DDI

A

valproate decreases lamotrigine metabolism → increased lamotrigine [ ] → increased risk of skin reactions (SJS/TEN)

  • initiate lamotrigine at lower dose (low-dose starter kit), titrate very carefully
  • counsel patients to watch out for rash
51
Q

what drugs are MAOIs

A
  • isocarboxazid
  • phenelzine
  • tranylcycpromine
  • rasagiline
  • selegiline
  • linezolid
52
Q

CYP3A4, P-gp inhibitors - calcinuerin inhibitors and mTOR kinase inhibitors DDI

A

decreased metabolism of CNI or mTOR kinase inhibitor → increased ADR/tox and increased BP, neprhotox and metabolic syndrome

  • CNIs: cyclosporine, tacrolimus
  • mTOR kinase inhibitors: sirolimus, everolimus
  • avoid using with CYP3A4 or Pgp inhibitors, or decrase dose of CNi and mTOR kinase cautiously
53
Q

MAOI - drugs that increase epi, NE, or DA DDI

A

MAOI drugs prevent metabolization of epi, NE, DA and 5-HT → increased NE, DA, epi → addition of other drugs/foods that increase NE, DA, epi → risk of htn crisis

avoid tyramine rich foods: aged cheeses, air-dried meats, sauerkraut

54
Q

MAOI - drugs that increase 5-HT DDDI

A

MAOI drugs prevent metabolization of epi, NE, DA, and 5-HT → increased 5-HT → addition of other drugs that increase 5-HT → increased risk of serotnonin syndrome
- antidepressants: SSRI, SNRI, TCA, mirtazapine, trazodone, buspirone
- opioids, analgesics: fentanyl, methadone, tramadol
- other: Li, st. john wort, dextroamphetamine (in highh doses)

washout period of 2 weeks, 5 for fluoxetine

55
Q

CYP3A4, P-gp inducers - calcinuerin inhibitors and mTOR kinase inhibitors DDI

A

increased metabolism of CNI or mTOR kinase inhibitor → decreased [ ] → increased risk of transplant rejection

  • CNIs: cyclosporine, tacrolimus
  • mTOR kinase inhibitors: sirolimus, everolimus
  • avoid using with CYP3A4 or Pgp inducers, or increase dose of CNi and mTOR kinase cautiously
56
Q

seizure medications that are CYP3A4 inducers - CYP3A4 substrates DDI

A

increased metabolism of substrates → decreaed drug levels

  • seizure meds: phenytoin, phenobarbital, primidone, carbamazepine (auto-inducer), oxCBZ
  • monitor drug levels, induction effect can take up to 4 weeks for full efefect
  • consider increasing substrate dose
  • if substrate is lamotrigine, start with high dose starter kit
57
Q

rifampin - CYP and Pgp substrates DDI

A

rifampin induces the enzyems → increased substrate metabolism → decreased level

  • monitor and icnrease dose of substrate as necessary
  • monitor INR for warfarin
58
Q

CYP3A4 inducers - CYP3A4 substrate opiods DDI

A

CYP3A4 induced → increased metabolism of opioid → decreased opioid [ ] → dereased pain relief

  • fentanyl, hydrocodone, oxycodone, methadone
  • assess breakthrough pain to see if maintenance dose is ncessary
  • caution, induction has lag time
59
Q

DDI for active smokers

A

smoking induces CYP1A2 → CYP1A2 substrates’ metabolism increased →decreased levels

  • some antipsychotics, antidepressants, hypnotics, anxiolytics, caffeine, theophylline, warfarin
  • start at a high dose
  • induction goes a way when a pt quits smoking (NRTs do NOT induce CYp1A2) → drug [ ] increase → increased tox
60
Q

serotonin syndrome s/s

A
  • autnomic dysfunction: diaphoresis, N/V vomiting
  • AMS: akathisia, anx, agitation, delirium
  • neuromuscular excitation: hyperreflexia, tremor, rigidity, tonic-clonic seizures
61
Q

medications with bleed risk and which ones you can use together

A
  • AC
  • antiplatelets
  • NSAIDs
  • SSRIs, SNRIs
  • 5Gs: garlic, ginger, ginkgo biloba, ginseng, glucosaame
  • Vit E

acceptable combos
- asa + prn nsaid
- SSRI/SNRI + prn nsaid
- DAPT if indicated
- bridging lovenox and warfarin

62
Q

drug combos that can cause hyperkalemia

A
  • RAAS: ACE, ARB, alikskiren, spirnolactone, eplerenone
  • K sparking diuretics: amiloride, triamterene
  • Other: KCl, CNI, SMX/TMP, canagliflozin, drospirenone containing OC

risk higher with renal impairment

63
Q

hyperkalemia s/s

A
  • weakness
  • palpitations
  • arrhythmias (can be fatal)
64
Q

QT prolonging drugs

A
  • antiarrhythmics
  • anti-infectives: -azole antifungals, antimalarials, lefumulin, macrolides, quinolones
  • antidepressants: SSRI (lexapro and citalopram), TCA, mirtazapine, trazodone, venlafaxine
  • APS
  • antiemetics: 5-HT3 antags, droperidol, metoclopramide, promethazine
  • onco drugs: androgen deprivation therapy, TKIs, arsenic trioxide
  • other: cilstazole, donpezil, finglimod, hydroxyzine, loperamide, ranolazine, solfenacin, methadone
65
Q

QT prolongation risk factors

A
  • high doses
  • high drug levels dt DDI
  • high drug levels dt renal disease or liver disease
  • multiple drugs with QT prolongation
  • age 60+ with CVD (HF, MI)

do not exceed citalopram 20mg in elderly or lexapro 10mg in elderly

66
Q

antiarrhymic of choice in HF

A

amiodarone

67
Q

CNS depressing drugs

A
  • opioids
  • skeletal muscle relaxants
  • antiseizure emds
  • benzos
  • barbituates
  • hypnotics
  • antidepressants: mirtazapine, trazodoe
  • antihypertensives: propranolol, clonidine
  • cannabis and related drugs
  • sedating antihistamines
  • some NSAIDs
68
Q

CNS-depressant effects

A
  • somnolence
  • dizziness
  • confusion
  • cog impairment
  • altered consicousness
  • falls
69
Q

ototoxic drugs

A
  • aminoglycosides: genamicin, tobramycin, amikacin etc.
  • cisplatin
  • loop diuretics
  • salicylates: asa
  • vancomycin
70
Q

nephrotox drugs

A
  • anti-infectives: AGs, amphotericin B, polymyxins, vanco
  • cisplatin - use with amifostine to protect kidneys
  • CNI
  • loop diuretics
  • NSAIDs
  • radiographic contrast die
71
Q

anti-choliergic drugs

A
  • antidepressants/APS: paroxetine, TCAs, first gen APS
  • sedating antihistamines
  • centrally-acting anticholinergics: benztropine
  • muscle relaxants
  • anti-muscarninics: oxybutynin, tolterodine, darifenacin
  • others: atropie, belladonna, dicylomie
72
Q

PDE-5 inhibitors with CYP3A4 inhibitors or nitrates or alpha 1 blockers DDI

A

hypotension
- CYP3A4 inhibitors → decrease metabolism → increased [ ]→ increased ADR
- alpha-1 blockers also cause vasodilation → additive effect → hypotension
- nitrates → vasodilation → additive hypotension → severe hypotension whch can be fatal

start at low doses

73
Q

common CYP3A4 substrates

A
  • analgesics: fentanyl, hydrocodone, methadone, oxycodone
  • anticoags: apixaban, rivaroxaban, R-warfariin
  • CV drugs: amiodarone, amlodpine, dilt, verapamil
  • immunosuppressants: cyclosporine, tacrolimus, sirolimus
  • statins: atorva, lova, simva
  • PDE-5 inhibitors
  • ethinyl estradiol
74
Q

common CYP3A4 inducers

A
  • CBZ (OxCBZ)
  • phenobarb
  • phenytoin
  • rifampinn
  • smoking
  • st. john wart
75
Q

common CYP3A4 inhibitors

A
  • anti-infectives: clarithyromyci, erythromycin, azole antifungas
  • CV drugs: amiodarone, dilt, verapamil
  • key HIV drugs: cobicistat, protease inhibitors, ritonavir
  • cyclosporine
  • grapefruit juice
76
Q

common CYP1A2 substrates

A
  • R-warfarin
  • theophylline
77
Q

common CYP1A2 inducers

A
  • CBZ
  • phenobarb
  • phenytoin
  • rifampi
  • smoking
  • st. john wart
78
Q

common CYP1A2 inhibitors

A
  • ciprofloxacin
  • fluvoxamine
79
Q

common CYP2C9 substrates

A

S-warfarin

80
Q

common CYP2C9 inducers

A
  • CBZ
  • pheobarb
  • phenytoin
  • rifampin
  • smoking
  • st. john wort
81
Q

comon CYP2C0 inhibitors

A
  • amiodarone
  • flucoazole
  • metronidazole
  • SMX/TMP
82
Q

common CYP2C19 substrates

A

clopidogrel

83
Q

commo CYP2C19 inhibitors

A
  • esomeprazole
  • omeprazole
84
Q

common CYP2D6 substrates

A
  • analgesics: codeine, meperidine, tramadol
  • various antidepressants and APS
  • tamoxifen
85
Q

common CYP2D6 inhibitors

A
  • amiodarone
  • duloxetine
  • fluoxetine
  • paroxetine

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