Interactions / P450 Flashcards
Progesterone is metabolized by 3A4, and should be avoided with what anitfungal medication?
Ketaconazole
Rifampin _______ (Increase/decreases) OCP efficacy
decreases
Which THREE AEDs may decrease OCP efficacy?
What are THREE non-OCP contraceptive methods to prevent this?
- Carbamazepine
- Phenobarbital
- Phenytoin
Alternatives……
- IUD
- DMPA
- Implants
Which ABx potentially decrease ethinyl estradiol concentration?
Which ABx may cause breakthrough bleeding?
Tetracyclines and PCNs
Ampicillin
Is Mifepristone a P450 drug?
Yes
T/F: Tamoxifen is NOT a P450 drug?
False
What anticoagulant does Tamoxifen interact with?
Warfarin
Does Tamoxifen interact with ALL Aromatase inhibitors?
No, only…..
Anastrozole
Letrozole
Will Tamoxifen interact with Rifampin?
Yes
Is it okay to give Toremifene with drugs that may prolong a QT?
No
T/F: Fluvestrant interacts with P450 medications
False
It has NO P450 interactions
Why should nitrates be avoided when using PDE5 inhibitors to treat ED?
Increase in hypotension
Which PDE5 Inhibitor should be avoided with anti-arrhythmics due to an increased risked of QT prolongation?
Vardenafil
Why should diltiazem be avoided in patients taking Tamsulosin?
Tamsulosin decreases the metabolism of diltiazem
Which TWO AEDs reduce the effectiveness of Tamsulosin?
Phenytoin
Carbamazepine
Fluconazole, Verapamil, and Diltiaem all ______ (increase/decrease) silodosin levels?
Increase
If silodosin is given with PDE5 inhibitors what may occur?
Orthostatic Hypotension
T/F: Saw Palmetto has the potential to interact with anti-coagulants
True
Are the anticholinergics used in OAB treatment metabolized by P450?
If yes, which drugs may be contraindicated due to being P450 inhibitors?
Yes
Avoid….
Azoles
Macrolides
Cetirizine
What is a major concern in giving tolterodine to patients who 2D6 poor metabolizers?
Prolonged QT
Does Trospium have P450 interactions?
No
Mirabegron is a CYP2D6 inhibitor…..
Which Beta-Blocker for HTN should be avoided when prescribing this medication?
Metoprolol
Carbamazepine is a CYP 3A4 _________.
Autoinducer
Lamotrigine’s half-life is _______ (increased/decreased) by Valproic Acid?
Increased
What FOUR AEDs will decrease the concentration of Topiramate?
- Valproic Acid
- Phenytoin
- Carbamazepine
- Lamotrigine
Phenytoin will ______ (increase/decrease) concentrations of almost every other AED
Decrease
Other than AEDs, what additional medications will phenytoin decrease the levels of?
Acetaminophen Amiodarone Doxycycline Furosemide Metroniadazole Prednisone Rifampine Warfarin
A patient currently being treated with doxycylcine for Lyme disease is given Phenytoin, what may happen to the level of doxycycline in their blood?
Decrease
A patient with a UTI is given ciprofloxacin, what would happen to the levels of phenytoin if it were administered?
Decrease
Will amiodarone increase or decrease phenytoin levels?
Increase
Perampanel is a P450 3A4 _______.
Substrate
Perampanel will ______ (increase/decrease) the effects of OCPs?
Decrease
If a patient on anti-coagulants is given Phenobarbital, what are you concerned about?
Decrease anti-coagulant activity
Would you expect the half-life of doxycycline to be longer or shorter if given with phenobarbital?
Shorter
For up to 2 weeks after phenobarbital is discontinued
Valproic acid will ________ (increase/decrease) henobarbital levels in the serum?
Increase
T/F: MOAIs prolong the effect of barbiturates
True
Phenobarbital _______ (increases/decreases) the effect of estradiol by ________ (increasing/decreasing) it’s metabolism
Decreases
Increasing
