Drug Interactions

Question 1

Risk from concurrent BZD and opioid use?

Answer 1

Sedation, respiratory depression, coma, death

Question 2

Drugs that have reduced absorption due to polyvalent ions

Answer 2

FQ, tetracycline, bisphosphonates, levothyroxine

Question 3

Drug that blocks the renal excretion of penicillin to ↑ its concentration

Answer 3

Probenacid

Question 4

CYP Inhibitors

Answer 4

Grapefruit
Protease Inhibitor
Azole Antifungals
Cyclosporine, cobicistat
Macrolides (not azithromycin)
Amiodarone (dronedarone)
Non-DHP CCB

Question 5

CYP inducers

Answer 5

Phenytoin
Smoking
Phenobarbital
Oxcarbazepine
Rifampin
Carbamazepine
St. John’s Worts

Question 6

What is the lag time for the disconintuation of an CYP inducer

Answer 6

2-4 wks

Question 7

What is enterohepatic recycling

Answer 7

Drug being reabsorbed in small intestine → enter the portal vein → travel back to liver

Question 8

How do you adjust amiodarone and warfarin concurrently?

Answer 8

Amiodarone 1st → warfarin: start with warfarin ≤5 mg

Warfarin 1st → amiodarone: Reduce warfarin dose by 30-50%

Question 9

How do you adjust amiodarone and digoxin concurrently?

Answer 9

Amiodarone 1st → digoxin: Start low dose digoxin of 0.125 mg

Digoxin 1st → amiodarone: Reduce digoxin by 50%

Question 10

Drug interaction with dioxin and loops

Answer 10

Loops an exacerbate renal impairment → Digoxin toxicity

Toxicity → ↓ K, Mg, and ↑ Calcium
Loop → ↓ K, Mg, Ca, Na

Question 11

Drugs that ↓ HR

Answer 11

Beta blocker, digoxin, non-DHP CCB, amiodarone, clonidine

Question 12

DI with statins and strong CYP3A4 inhibiots

Answer 12

Increased levels of atorvastatin, simvastatin, lovastatin

CI: Simvastatin, lovastatin

Question 13

Statins not metabolized by CYP enzymes

Answer 13

Rosuvastatin, pitavastatin, pravastatin

Question 14

Opioid metabolized by CYP3A4

Answer 14

Fentanyl, hydrocodone, oxycodone, methadone

Question 15

Precautions when using valproate with lamotrigine?

Answer 15

Valproate ↓ lamotrigine metabolism therefore Lamictal is dispensed as a starter kit with lower doses

Question 16

Neurotransmitters affected by MOA? ADRs associated with elevations in neurotransmitters?

Answer 16

Epi, NE, DA: Hypertensive crisis
5-HT: Serotonin syndrome

Question 17

Washout period when switching drugs with MOA or serotonergic drugs? Exceptions?

Answer 17

2 weeks

Exceptions: Fluoxetine which is 5 wks

Question 18

Food containing tyramine

Answer 18

Fermented, pickled, aged

Question 19

Drugs that ↑ NE, E, DA

Answer 19

SNRIs, bupropion, levodopa, stimulants, MOAI

Question 20

Drugs that ↑ 5-HT

Answer 20

Trazadone, mirtazipine, SSRI, SNRI, MOAI

Fentynal, methadone, tramadol

St. Johns, buspirone, dextromethorphan

Question 21

Dosing of lamotrigine with CYP inducer

Answer 21

Higher-dose lamotrigine starter kit

Question 22

Drugs affected when someone quits smoking?

Answer 22

R-isomer warfarin

Question 23

Drugs that ↑ bleeding

Answer 23

NSAIDs
SSRIs, SNRIs
Anticoagulants
Antiplatelets
Natural products: Ginkgo, ginseng, garlic, ginger, glucosamine

Question 24

Drugs that induce hyperkalemia

Answer 24

ACEI, ARB
Potassium sparing
Potassium

Question 25

Drugs with the highest risk of QTc prolongation

Answer 25

Antiarrhythmics (1a, 1c, III) Anti-infectives (Azole, antimalarials, lefamulin, macrolides, FQ) SSNRI (citalopram and escitalopram) TCAs Antipsychotics (Ziprasidone, haloperidol, venlafaxine) 5-HT3 receptor antagonists ADT TKI

Question 26

How to avoid QTc prolongation with depression

Answer 26

Citalopram: Don't exceed 40 mg QD or 20 mg QD (>60YO) Escitalopram: Don't exceed 20 mg QD or 10 mg (elderly)

Question 27

What is the safest SSRI for CVD

Answer 27

Sertraline

Question 28

Sx of CNS depression

Answer 28

Somnolence, dz, confusion/cognitive impairment, altered consciousness, falls Avoid with alcohol

Question 29

Drugs that cause ototoxicity

Answer 29

Aminoglycoside Cisplatin Loop Salicilates Vancomycin

Question 30

Drugs that cause nephrotoxicity

Answer 30

Anti-infectives (AG, Ampho B, polymyxins, Vanc) Cisplatin Calcinurine Inhibitors Loop NSAID Dyes

Question 31

How to avoid nephrotox in cisplatin

Answer 31

Administer with amifostine (Ethyol)

Question 32

What drug class is the highest risk for elders due to fall risk

Answer 32

Anticholinergics

Question 33

Drugs that can cause orthostasis

Answer 33

PDE5 Inhibitor + CYP3A4 inhibits or nitrates or a-1 blockers

Question 34

What to do when taking PDE5-i with CYP3A4 inhibitors

Answer 34

Start with half dose of starting dose pf PDE5

Question 35

What to do when taking PDE5-i with a-1 blocker

Answer 35

Start with lower dose when adding another class

Question 36

Most potent warfarin isomer? Metabolized

Answer 36

S by CYP2C9

Question 37

Clopodogrel metabolsim

Answer 37

CYP2C19

Question 38

Opiods metabolized by CYP2D6

Answer 38

Codeine, meperidine, tramadol