Interactions / P450

Question 1

If Colchicine was given with a P450 Inhibitor (Clarithromycin, Intraconazole) what would happen to the plasma levels of colchicine?

Answer 1

Increased plasma levels of Colchicine (leading to toxicity)

Question 2

If allopurinol was given with an immunosuppressant like azathioprine……

What may occur?

Answer 2

Reduce the efficacy of Allopurinol

Question 3

Should Allopurinol be given with Warfarin?

Answer 3

No

Question 4

If Allopurinol is given with Theophylline…..

What may occur?

Answer 4

Increased Theopylline levels

Question 5

Probenecid ______ (increases/decreases) PCN secretion

Answer 5

Decreases Secretion of PCN which in turn increases PCN levels

Question 6

Lesinurad is a weak inducer of what P450 isoenzyme?

Answer 6

3A4

Question 7

Why should vitamin D be avoided in patients on corticosteroids?

Answer 7

Corticosteroids impair Vitamin D metabolism

Question 8

Can patients on Vitamin D take Orlistat?

Answer 8

No, Orlistat decreases the metabolism of fat-soluble vitamins

Question 9

Should patients on Phenobarbital or Phenytoin take Vitamin D?

Answer 9

No, because those medications increase Vitamin D metabolism to their inactive compounds

Question 10

What drugs will Atomoxetine interact with?

Answer 10

2D6 Inhibitors
MAOIs
Albuterol

Question 11

Zolpidem (Ambien) will interact with medications that a substrates of what P450 isoenzyme?

Answer 11

CYP 3A4 Substrates

Question 12

Should Eszopiclone (Lunesta) be used in combination with EtOH and CNS Depressants?

Answer 12

No

Question 13

Why should anticoagulants be avoided with mealtonin?

Answer 13

Melatonin potentiates anticoagulation

Question 14

Why should patients taking AEDs avoided Melatonin?

Answer 14

Melatonin inhibits the effects of AEDs

Question 15

Would you expect to see an increased or decreased efficacy of Anti-hypertensives if taken with melatonin?

Answer 15

Increased Efficacy

So you would see a LOWER BP

Question 16

Why should diabetics avoid melatonin?

Answer 16

Leads to increased glucose levels

Question 17

Tasimelteon should be avoided with strong CYP 1A2 __________ (inhibitor/Inducer)

Tasimelteon should be avoided with strong CYP 3A4 __________ (inhibitor/Inducer)

Answer 17

1A2 Inhibitors

3A4 Inducers

Question 18

Should Tasimelteon be used in pregnancy?

Answer 18

No, potential for fetal harm

Question 19

Which SSRIs are 2D6 Inhibitors?

Answer 19

Fluoxetine
Paroxetine
Sertraline

Question 20

Which SSRIs are 2C9 Inhibitors?

Answer 20

Paroxetine

Sertraline

Question 21

Which TWO SSRIs have the fewest drug interactions?

Answer 21

Citalopram

Escitalopram

Question 22

Levomilnacirpan is a strong 3A4 ________ (inhibitor/Inducer)

Answer 22

Inhibitor

Question 23

Which SNRIs are 2D6 Inhibitors?

Answer 23

Vortioxetine

Duloxetine

Question 24

Should SNRIs be used with platelet inhibitors?

Answer 24

No

Question 25

If Venlafaxine (Effexor) is used in combination with SSRIs, NSAIDs, ASA, or Warfarin……

What is the patient at an increased risk for?

Answer 25

Bleeding

Question 26

Should Duloxetine (Cymbalta) be used with MAOIs?

Answer 26

No

Question 27

T/F: Milnacipran has NO P450 interactions

Answer 27

True

Question 28

Should TCAs be used with Anticholinergic medications?

Answer 28

No (Increased Anticholinergic Effect)

Question 29

TCAs are CYP 2D6 _______ (inducers/Substrates/Inhibitors)

Answer 29

Substrates

So avoid in poor metabolizers or SSRIs which are inhibitors

Question 30

St. John’s Wort is a potent P450 ________

Answer 30

Inducer

Question 31

You should _______ (increase/decrease) the dose of Clozapine when used in combination with Ciprofloxacin

Answer 31

Decrease the Dose of Clozapine with P450 1A2 inhibitors like ciprofloxacin

(Avoid this medication in strong P450 Inhibitors)