CYP interactions

[uhmocksuhsillen]

How much do you worry/check CYP interactions? I find myself constantly checking medications to see if there are any interactions. And even when there are, I wonder how clinically relevant they may be. I know some of the big ones, i.e. prozac with 2d6, luvox with 1a2, etc. But how frequently are you guys looking these up or have you just committed them all to memory?

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[ObsequiousAplomb]

If your prescribing system tells you when there's an interaction you quickly learn the ones that interact and why so that you can feel safe clicking ignore (or you just learn to click ignore regardless of feelings). Occasionally I am reminded of interactions I had forgotten (like that fluoxetine also inhibits 2b6, that bupropion inhibits 2d6 but is metabolized by b6), but honestly it never comes up clinically beyond me titrating more slowly or using lower / higher doses as needed. When there's a narrow therapeutic index or a need for serum levels, you just check the levels and adjust doses as necessary, not entirely different from what you would do if the interaction weren't written down somewhere.

 

[FlowRate]

The ones I think about most often, like OA mentioned, are bupropion and fluoxetine/duloxetine. If a patient has a gigantic med list of stuff I'm not familiar with then I may enter it all into lexicomp since our build of epic doesn't usually throw warnings for CYP interactions. If your status as "med student" is accurate, or if you're early in residency, then I would encourage continuing to look it up until you start to build familiarity with the majority of the psychiatric armamentarium as well as other common non-psych medications.

 

[uhmocksuhsillen]

The ones I think about most often, like OA mentioned, are bupropion and fluoxetine/duloxetine. If a patient has a gigantic med list of stuff I'm not familiar with then I may enter it all into lexicomp since our build of epic doesn't usually throw warnings for CYP interactions. If your status as "med student" is accurate, or if you're early in residency, then I would encourage continuing to look it up until you start to build familiarity with the majority of the psychiatric armamentarium as well as other common non-psych medications.

I'm actually senior resident, so I feel like I should know more than the basic interactions at this point.

 

[Stagg737]

I'm actually senior resident, so I feel like I should know more than the basic interactions at this point.

Imo you should know the ones that have major effects on CYP enzymes (prozac, bupropion, fluvoxamine, etc) and which meds are "dirty" vs "clean" (ie Luvox is dirty, Lexapro is pretty clean). I think it's also important to know classes of non-psych meds with significant CYP interactions (antibiotics and antiretrovirals are ones I always check).

If your EMR has an interaction checker it can be great, or sites like Lexacomp are helpful. I like using IU's Flockhart Table as it's pretty thorough and you can click on drugs to see other specific drug interactions and references. If you want to go really in-depth you can use DrugBank, it's a free site managed by the University of Alberta along with The Metabolomics Innovation Centre (Idk who they are). It's by far the most comprehensive and detailed pharmacology site I'm aware of and has been one of my favorite resources for years. Links for Flockhart and DrugBank below:

Drug Interaction Flockhart Table | Clinical Pharmacology | IU School of Medicine

A teaching and reference tool for health care providers and researchers interested in drug interactions that are mediated by cytochrome P450 enzymes.

medicine.iu.edu

DrugBank Online | Database for Drug and Drug Target Info

Access the world’s pharmaceutical knowledge database. Information on drugs, drug targets, and more, used by researchers and health professionals globally.

go.drugbank.com

 

[FlowRate]

This also prompted me yesterday to ask around and I learned that our Epic system suppresses CYP interaction warnings (since they're often irrelevant or excessive) but you can find them when ordering a new drug by clicking on the "options" dropdown on the top right of the order window and then clicking "interactions." Never would have thought to look there since "options" in epic is usually random minor configuration stuff, not useful tools.

 

[annoyedpsychiatrist]

i memorized relevant psych ones. I occasionally look at interaction checker, but from reading/memorizing/checking stuff in the past a lot of it has just become experience/memory

 

[Merovinge]

Imo you should know the ones that have major effects on CYP enzymes (prozac, bupropion, fluvoxamine, etc) and which meds are "dirty" vs "clean" (ie Luvox is dirty, Lexapro is pretty clean). I think it's also important to know classes of non-psych meds with significant CYP interactions (antibiotics and antiretrovirals are ones I always check).

If your EMR has an interaction checker it can be great, or sites like Lexacomp are helpful. I like using IU's Flockhart Table as it's pretty thorough and you can click on drugs to see other specific drug interactions and references. If you want to go really in-depth you can use DrugBank, it's a free site managed by the University of Alberta along with The Metabolomics Innovation Centre (Idk who they are). It's by far the most comprehensive and detailed pharmacology site I'm aware of and has been one of my favorite resources for years. Links for Flockhart and DrugBank below:

Drug Interaction Flockhart Table | Clinical Pharmacology | IU School of Medicine

A teaching and reference tool for health care providers and researchers interested in drug interactions that are mediated by cytochrome P450 enzymes.

medicine.iu.edu

DrugBank Online | Database for Drug and Drug Target Info

Access the world’s pharmaceutical knowledge database. Information on drugs, drug targets, and more, used by researchers and health professionals globally.

go.drugbank.com

I agree, just remember the exceptions to the huristics (like Lexapro clean). For example Lexapro w/ Omeprazole, particularly in the elderly can be a big problem. I don't know of any other med that I worry about with Lexapro. Prozac/Abilify is probably the single most common one to see in CAP as this combination is very common these days.

 

[mistafab]

Many CYP interactions are not clinically relevant. It’s easier to remember which drugs are strong inhibitors/inducers, then remind yourself to be wary of med list or check interactions if selecting those medications to start. Also, if someone is stable on an HIV/CART regimen it is worth evaluating. AEDs should give you some pause of on the med list, as many alter metabolism as well as inhibit or induce.

fluvox
paroxetine
fluoxetine
bupropion
valproic acid
Any AED
Antibiotics
-azole antifungals
HIV meds (protease inhibitors)

For non -CYP interactions, many are just pharmacodynamic interactions that need to be wary of. Such as fentanyl patches and serotonin syndrome.