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NAPLEX 21 > Drug interactions > Flashcards

Drug interactions Flashcards

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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?

Study These Flashcards
A

CHICA

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

24
Q

Pgp inducers?

Study These Flashcards
A

PS CPR

phenytoin
st johns wort

carbamazepine
phenobarbital
rifampin

25
Pgp inhibitors?
CVAD amiodarone, diltiazem verapamil) cyclosporin
26
enterohepatic recycling inc or dec duration of action?
increases
27
describe enterohepatic recycling locations
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
What is the effect of amiodarone + warfarin?
INC WARFARIN LEVELS = DEC WARFARIN DOSE by 30-50% amiodarone inhibits 2C9, which metabolizes warfarin dec warfarin metabolism = inc INR = inc bleeding
29
what is the effect of amiodarone + digoxin?
DEC DIGOXIN DOSE BY 50% amiodarone inhibits Pgp; digoxin is a substrate of Pgp dec digoxin excretion = inc toxicity... risk of bradycardia
30
What is the effect of digoxin + loop?
DIGOXIN TOXICITY loops decrease K, Mg, Ca, Na Low K, Mg or Ca will worsen arrhythmias
31
What are drugs that decrease heart rate and have additive effects?
amiodarone digoxin BB clonidine
32
What is the effect of statins + strong CYP3A4 inhibitors | GPACMAN
INC levels of Cyp3a4 substrates: lovastatin, simvastatin, atorvastatin simva and lova are contraindicated
33
What is the effect of warfarin + 2C9 inhibitors & inducers?
inhibitors = INC levels of warfarin = INC INR inducers = dec levels of warfarin = dec INR
34
What are some 2c9 inhibitors?
BAMA increases warfarin azoles, Bactrim, amiodarone, metronidazole
35
what are some 2c9 inducers?
decrease warfarin rifampin, st johns wort
36
What is the effect of 3a4 inhibitors + 3a4 substrates?
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
What drugs cannot be taken with grapefruit?
SLANT amiodarone, simvastatin, lovastatin, nefidipine, tacrolimus
38
what opioids are 3a4 substrates?
fentanyl hydrocodone oxycodone methadone
39
what is the effect of valproate + lamotrigine?
INC LEVELS OF LAMOTRAGINE (skin reactions!!) valproate decreases lamotrigine metabolism
40
blocking MAO will inc or dec epi, NE, DA, and 5Ht?
increase! (epi, NE, DA hypertensive crisis) 5ht= SS reason for washout period; fluoxetine - 5 weeks
41
What are drugs that will increase serotonin?
SSRis, SNRIs, TCAs, MAOi, mirtazapine, trazodone, fentanyl, methadone, tramadol buspirone, delsym, LITHIUM, st johns wort triptans linezolid
42
MAO inhibitors + tyramine rich foods will cause?
hypertensive crisis do not eat aged cheese, air dried meats, sauerkraut
43
2d6 inhibitors + 2d6 substrates?
dec drug metabolism = toxicity avoid use or dec dose of substrate
44
examples of 2d6 inhibitors?
F FAP amiodarone fluoxetine paroxetine fluvoxamine
45
3a4 or Pgp inhibitors + calcineurin inhibitors (tacrolimus, cyclosporine) or mTOR kinase inhibitors (sirolimus, everolimus)
decrease drug metabolism = inc toxicity avoid use together or decrease dose of CNI, mTOR
46
what is a common drug that can decrease drug levels of phenytoin, phenobarbital, primidone, carbamazepine/oxcarbamazpine
oral contraceptives... loss of seizure control
47
smoking (inducer 1a2) + some antipsychotics, antidepressants, hypnotics, anxiolytics, caffeine, theophylline, warfarin (r-isomer)
smokers who quit: drug concentrations will increase current smoker: decrease levels
48
Bleeding risk drugs?
anticoagulants antiplatelets NSAIDs SSRi, SNRIs garlic, ginger, ginkgo, ginseng, glucosamine Vitamin E willow bark fish oils (high mg)
49
what can cause high K?
spironolactone, eplerenone - highest risk ACE, ARBs, entresto amiloride, triamterene, KCl, tacrolimus, cyclosporin, canagliflozin, bactrim, drospirenone OC
50
QT prolongation drugs?
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
What drugs cause ototoxicity?
AG cisplatin loops salicylates vancomycin
52
what drugs cause nephrotoxicity?
AG, ampho B, polymyxins, vancomycin cisplatin (use amifostine to protect kidneys) cyclosporine, tacrolimus loops NSAIDs radiographic contrast dye
53
PDE-5 inhibitors should start with a lower dose when used in combo with either of these 3 drug classes
3a4 inhibitors nitrates alpha-1 blockers
54
what drugs can cause anticholinergic toxicity?
paroxetine, TCA, FGA sedating antihistamines atropine, dicyclomine, meclisine benztropine baclofen, carisodolol, cyclobenzaprine oxybutinin, tolterodine
55
fentanyl, hydrocodone, methadone, oxycodone apixaban, rivaroxaban, R-warfarin amlodipine cycloposporin, tacrolimus, sirolimus atorvastatin, lovastatin, simvastatin avanafil, sildenafil, tadalafil, vardenafil ethinyl estradiol what cyp?
3a4 substrate
56
carbamazpine, oxcarbamazpine, phenobarbitol, phenytoin, rifampin, smoking, st John wort
3a4 inducers
57
clarithromycin, erythromycin, azoles amiodarone, diltiazem, verapamil cobicstat, protease inhibitors, ritonavir cyclosporine, grapefruit
3a4 inhibitors

NAPLEX 21 (60 decks)

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