Interactions / P450

Question 1

Progesterone is metabolized by 3A4, and should be avoided with what anitfungal medication?

Answer 1

Ketaconazole

Question 2

Rifampin _______ (Increase/decreases) OCP efficacy

Answer 2

decreases

Question 3

Which THREE AEDs may decrease OCP efficacy?

What are THREE non-OCP contraceptive methods to prevent this?

Answer 3

1. Carbamazepine
2. Phenobarbital
3. Phenytoin

Alternatives……

1. IUD
2. DMPA
3. Implants

Question 4

Which ABx potentially decrease ethinyl estradiol concentration?

Which ABx may cause breakthrough bleeding?

Answer 4

Tetracyclines and PCNs

Ampicillin

Question 5

Is Mifepristone a P450 drug?

Answer 5

Yes

Question 6

T/F: Tamoxifen is NOT a P450 drug?

Answer 6

False

Question 7

What anticoagulant does Tamoxifen interact with?

Answer 7

Warfarin

Question 8

Does Tamoxifen interact with ALL Aromatase inhibitors?

Answer 8

No, only…..

Anastrozole
Letrozole

Question 9

Will Tamoxifen interact with Rifampin?

Answer 9

Yes

Question 10

Is it okay to give Toremifene with drugs that may prolong a QT?

Answer 10

No

Question 11

T/F: Fluvestrant interacts with P450 medications

Answer 11

False

It has NO P450 interactions

Question 12

Why should nitrates be avoided when using PDE5 inhibitors to treat ED?

Answer 12

Increase in hypotension

Question 13

Which PDE5 Inhibitor should be avoided with anti-arrhythmics due to an increased risked of QT prolongation?

Answer 13

Vardenafil

Question 14

Why should diltiazem be avoided in patients taking Tamsulosin?

Answer 14

Tamsulosin decreases the metabolism of diltiazem

Question 15

Which TWO AEDs reduce the effectiveness of Tamsulosin?

Answer 15

Phenytoin

Carbamazepine

Question 16

Fluconazole, Verapamil, and Diltiaem all ______ (increase/decrease) silodosin levels?

Answer 16

Increase

Question 17

If silodosin is given with PDE5 inhibitors what may occur?

Answer 17

Orthostatic Hypotension

Question 18

T/F: Saw Palmetto has the potential to interact with anti-coagulants

Answer 18

True

Question 19

Are the anticholinergics used in OAB treatment metabolized by P450?

If yes, which drugs may be contraindicated due to being P450 inhibitors?

Answer 19

Yes

Avoid….

Azoles
Macrolides
Cetirizine

Question 20

What is a major concern in giving tolterodine to patients who 2D6 poor metabolizers?

Answer 20

Prolonged QT

Question 21

Does Trospium have P450 interactions?

Answer 21

No

Question 22

Mirabegron is a CYP2D6 inhibitor…..

Which Beta-Blocker for HTN should be avoided when prescribing this medication?

Answer 22

Metoprolol

Question 23

Carbamazepine is a CYP 3A4 _________.

Answer 23

Autoinducer

Question 24

Lamotrigine’s half-life is _______ (increased/decreased) by Valproic Acid?

Answer 24

Increased

Question 25

What FOUR AEDs will decrease the concentration of Topiramate?

Answer 25

1. Valproic Acid 2. Phenytoin 3. Carbamazepine 4. Lamotrigine

Question 26

Phenytoin will ______ (increase/decrease) concentrations of almost every other AED

Answer 26

Decrease

Question 27

Other than AEDs, what additional medications will phenytoin decrease the levels of?

Answer 27

``` Acetaminophen Amiodarone Doxycycline Furosemide Metroniadazole Prednisone Rifampine Warfarin ```

Question 28

A patient currently being treated with doxycylcine for Lyme disease is given Phenytoin, what may happen to the level of doxycycline in their blood?

Answer 28

Decrease

Question 29

A patient with a UTI is given ciprofloxacin, what would happen to the levels of phenytoin if it were administered?

Answer 29

Decrease

Question 30

Will amiodarone increase or decrease phenytoin levels?

Answer 30

Increase

Question 31

Perampanel is a P450 3A4 _______.

Answer 31

Substrate

Question 32

Perampanel will ______ (increase/decrease) the effects of OCPs?

Answer 32

Decrease

Question 33

If a patient on anti-coagulants is given Phenobarbital, what are you concerned about?

Answer 33

Decrease anti-coagulant activity

Question 34

Would you expect the half-life of doxycycline to be longer or shorter if given with phenobarbital?

Answer 34

Shorter | For up to 2 weeks after phenobarbital is discontinued

Question 35

Valproic acid will ________ (increase/decrease) henobarbital levels in the serum?

Answer 35

Increase

Question 36

T/F: MOAIs prolong the effect of barbiturates

Answer 36

True

Question 37

Phenobarbital _______ (increases/decreases) the effect of estradiol by ________ (increasing/decreasing) it's metabolism

Answer 37

Decreases Increasing