RxPrep > Drug Interactions > Flashcards

Drug Interactions Flashcards

(47 cards)

Study These Flashcards
1
Q

What are pharmacodynamic drug interactions?

A
  1. additive effects (binding to the same rec)
  2. additive effects with different MOA (binding to a different rec)
  3. Antagonist blocking agonist from rec
  4. synergy when 2 drugs are used together for a greater therapeutic effect effecr
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are PK drug interactions?

A

Changes (increase/decrease) in ADME

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

What drugs can decrease absorption?

A
  1. Chelation: A drug binds to polyvalent cations
  2. Binding properties: drugs bind to antacids, multivitamins, bile acid resins, phos binders, quinolones, tetracyclines, levothyroxine, oral bisphosphonates
  3. Acidic environment (the drug will not be absorbed in high pH; H2RA/PPI decrease absorption of azoles)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How is excretion decreased?

A
  1. Probenicid blocks renal excretion of PCN
  2. Bicarb given for salicylate toxicity alkalinizes the urine, the salicylate becomes ionized and less is reabs in the kidneys
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the benefits of prodrugs?

A
  1. Increase bioavailability
  2. Prevent drug abuse
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are warnings with codiene formulations?

A
  1. Risk of morphine toxicity with ultra-rapid 2D6 metabolizer
  2. Poor analgesia with poor 2D6 metabolizers
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are warnings with clopidogrel?

A
  1. Risk of subtherapeutic conc with 2C19 inhibitors (omeprazole, esomeprazole)
  2. Risk of subtherapeutic conc with 2C19 poor metabolizers
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What Phase of metabolism do CYP enzymes catalyze?

A

Phase 1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What enzymes catalyze Phase 2 metabolism rxns?

A
  1. Uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1)
  2. N-acetyltransferse (NAC)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What drugs are major substrates of 3A4?

A
  1. Analgesics (Fentanyl/Hydrocodone/ Methadone/Oxycodone/tramadol/nbuprenorphine)
  2. Anticoagulants (Apixaban/Rivaroxaban/r-warfarin)
  3. CV drugs (Amiodarone/Amlodipine/Diltiazem/Verapamil)
  4. Immunosuppressants (Cyclosporine/ Tacrolimus/Sirolimus)
  5. Statins (Atorvastatin/Lovastatin/ Simvastatin)
  6. HIV drugs (NNRTIs/atazanavir/efavirenz)
  7. PDE-5 inhibitors
  8. Others (ethynyl estradiol)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are common moderate/strong 3A4 inhibitors?

A
  1. Grapefruit
  2. Protease inhibitors
  3. Amiodarone
  4. Cyclosporine/cobicistat
  5. Macrolides (not azythromycin)
  6. Azole antifungals
  7. Non-DHP CCBs
    ***GPACMAN
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What drugs have specific recommendations against use with grapefruit in their packaging?

A
  1. Amiodarone
  2. Simvastatin
  3. Lovastatin
  4. Nifedipine
  5. Tacrolimus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are common moderate/strong 3A4 inducers?

A
  1. Phenytoin
  2. Smoking
  3. Phenobarbital
  4. Oxcarbazepine
  5. Rifampin (rifabutin/rifapentine not as much induction)
  6. Carbamazepine
  7. St. John Wort
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How long does it take for CYP enzyme induction to start/ stop after D/C inducer?

A
  1. Takes time; full effect on drug levels may not be seen for up to 4 weeks
  2. Takes 2-4 weeks for induction to D/C completely; enzymes destroyed based on half-life
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the function of a P-glycoprotein (P-gp) efflux pump?

A

Located in cells of the GI tract; transport drugs/metabolites out of the body by pumping them into the gut so then can be excreted in the stool

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

What drugs are P-gp substrates?

A
  1. Anticoagulants (PO Xa inhibitors, dabigatran)
  2. CV drugs (Digoxin, Diltiazem, Verapamil, ranolazine, carvedilol)
  3. HCV drug (sofosbuvir)
  4. Immunosuppressants (Cyclosporine, Tacrolimus, sirolimus)
  5. Other (Colchicine, atazanavir, dolutegravir, posaconazole, raltegravir, saxagliptin)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What drugs are inducers of P-gp?

A
  1. Phenytoin
  2. St. john wort
  3. Carbamazepine
  4. Phenobarbital
  5. Rifampin
  6. dexamaethasone
  7. tipranavir
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What drugs are inhibitors of P-gp?

A
  1. Anti-infectives (clarithromycin, itraconazole, posaconazole)
  2. CV drugs (Amiodarone, Diltiazem, Verapamil, dronedarone, quinidine, carvedilol, conivaptan)
  3. HCV drugs (ledipsavir)
  4. HIV drugs (Cobicistat, Ritonavir)
  5. Others (Cyclosporine, flibanserin, ticagrelor)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is enterohepatic recycling?

Study These Flashcards
A

Drug metabolized by the liver is transported thru the bile and back into the gut; it is reabsorbed in the small intestine, enters the protal vein, and travels back to the liver; it increases drug duration (NSAIDs, mycophenolate, ezetimibe)

20
Q

What is the MOA of drug interaction with amiodarone and warfarin?

Study These Flashcards
A
  1. Amiodarone inhibits 2C9: start warfarin ≤5mg
  2. Warfarin (potent s-isomer) 2C9 substrate; increased INR and bleeding: decrease warfarin dose by 30-50% when starting amiodarone
21
Q

What is the MOA of drug interaction with amiodarone and digoxin?

Study These Flashcards
A
  1. Amiodarone inhibits P-gp: start digoxin at low dose (0.125mg QD)
  2. Digoxin is a substrate of P-gp (decrease PO digoxin by 50% when starting amiodarone; QOD dosing or 0.125mg QD if on 0.25mg QG): monitor for signs of digoxin toxicity
  3. Additive bradycardia and increased risk of arrhythmia
22
Q

What is the MOA of drug interaction with loop diuretics and digoxin?

Study These Flashcards
A
  1. Loop diuretics decrease K, Ca, Mg
  2. Digoxin toxicity increased with low K, Mg, and high Ca
  3. Low K, Mg, Ca will worsen arrhythmia
  4. Loop diuretics can exacerbate renal impairment –> increased digoxin toxicity due to decreased clearance
  5. Additive bradyarca with digoxin + BBs, clonidine, nonDHPs, Precedex
23
Q

What statins are not CYP substrates?

Study These Flashcards
A
  1. Rosuvastatin
  2. Pravastatin
  3. Pitavastatin
24
Q

What drugs are 2C9 inhibitors?

Study These Flashcards
A
  1. Amiodarone
  2. Metronidazole
  3. Sulfamethoxazole/Trimethoprim
  4. Fluconazole/ketoconazole/ voriconazole
  5. atazanavir/efavirenz/etravirine
  6. capecitabine/fluorouracil
  7. isoniazid/ oritavancin
  8. cimetidine
  9. gemfibrozil
  10. fluvoxamine/valproic acid
  11. zafirlukast (Accolate)
25
What drugs are inducers of 2C9?
1. Phenytoin 2. St. john wort 3. Carbamazepine 4. Phenobarb/primidone 5. Rifampin/ rifapentine 6. Smoking 7. ritonavir 8. aprepitant
26
What DI occurs with valproate and lamotrigine?
Valproate decreases Lamotrigine metabolism --> Increase risk of SJS/TENS/skin reactions *** Use lower dose of lammotrigine started kit
27
What drugs are MAO inhibitors?
1. Phenelzine 2. Isocarboxazid 3. Tranylcypromine 4. Isoniazid 5. Methylene blue 6. Selegiline 7. Rasagilline
28
What needs to be done when switching to or from a MAOi and serotenergic agent?
2-week washout period; EXCEPT fluoxetine 5 week washout
29
What food/drugs can increase risk of HTN crisis (DA, NE,EPI)?
1. SNRI/TCAs 2. Bupropion 3. Levodopa 4. Stimulants 5. Tyramine
30
What drugs can increase risk of serotonin syndrome?
1. Antidepressants: SSRI/ SNRI/TCA/ mirtazapine/trazodone 2. Opioids: fentanyl/methadone/ tramadol 3. Others: buspirone/dextromethorphan (high dose/abused)/ Lithium/ St. john wort
31
What foods can increase the risk of serotonin syndrome/HTN crisis?
Tyramine rich foods: Aged, pickled, fermented, smoked, air-dried meats, sauerkraut, some wine/beer
32
What are substrates of 2D6?
1. Analgesics (Codeine/Merperidine/Tramadol) 2. Antipsychotics/Antidepressants (many) 3. Others (Tamoxifen)
33
What drugs are 2D6 inhibitors?
1. Amiodarone 2. Duloxetine/Paroxetine/Fluoxetine 3. setraline/bupropion
34
What is the result of 3A4/P-gp inhibitor with transplant drugs?
Calcineurin inhibitors: Tacrolimus/Cyclosporine mTOR inhibitors: Sirolimus/Everolimus *** Decreases metabolism resulting in intoxicity and increased transplant drug levels
35
When should the high dose starter pack of lamotrigine be used?
Concurrent use of inducer: Phenytoin, phenobarb/primidone, oxcarbazepine, carbamazepine
36
What enzyme does smoking (cigarettes and marijuana) primarily induce?
1A2
37
How does smoking impact 1A2 substrates?
Substrates will have decreased levels
38
What should be done if a smoker quits?
Substrate drug concentrations will increase, may result in toxicity
39
How should serotinergic agents be discontinued and restarted?
Eliminate intitial drug prior to starting new serotinergic drug (2 week washout or 5 weeks for fluoxetine)
40
What are the symptoms of serotonin syndrome?
1. Autonomic dysfunction (N/V, hyperthermia, diaphoresis) 2. Altered mental status (akathisia, agitation, anxiety, delirium) 3. Neuromuscular excitation (hyperflexia, tremor, rigidty, tonic-clonic seizures)
41
What agents can cause additive hyperkalemia?
1. RAAS inhibitors (including spironolactone/eplerenone; highest w/ ARBs) 2. K-sparing diuretics (amiloride/triamterene) 3. Calcineurin inhibitors (tacrolimus/cyclosporine) 4. SMX/TMP 5. Canagliflozin 6. Drosperinone OC (Yasmin)
42
What drugs cause ototoxicity?
1. Aminoglycosides (gentamicin/tobramycin/amikacin)\ 2. Cisplatin 3. Loop diuretics (esp rapid IV) 4. Salicylates (aspirin, salsalate) 5. Vancomycin
43
What drugs are 1A2 substrates?
1. r-warfarin 2. Theophylline
44
What drugs are inhibitors of 1A2 (theophylline)?
1. Ciprofloxacin 2. Fluvoxamine 3. zileuton 4. atazanavie 5. cimetidine 6. propranolol
45
What drugs are inducers of 1A2 (theophylline)?
1. Carbamazepine 2. Phenobarbital 3. Phenytoin 4. Primidone 5. Rifampin/rifapentine 6. Ritonavir 7. Smoking 8. St, johns wort 9. aprepitant
46
What other drugs can increase theophylline levels?
1. Clarythromycin/erythromycin (3A4 inhibitors) 2. Alcohol/Disulfiram 3. Estrogen-containing oral contraceptives 4. methotrexate 5. pentoxyfylline 6. Propafenone 7. verapimil
47
What other drugs can decrease theophylline levels?
1. Fosphenytoin 2. levothyroxine
RxPrep
flashcards
Decks in class (69)
# Cards
Brainscape helps you reach your goals faster, through stronger study habits.
© 2026 Bold Learning Solutions. Terms and Conditions