Memorizing Cyp450 Inducers & Inhibitors

One of my favorite new apps on my Android phone is made by Pendragon Entertainment: USMLE Pharmacology.  Definitely recommend it – while I was setting it up yesterday, it asked me about cytochrome p450 inhibitors and inducers so many times that I accidentally learned them.

(I know, right?  Technology!)

It seems like the first step was being able to recognize that a drug is a cytochrome p450 something.  The commonly tested ones, at least on that app, were these:  Erythromycin, quinidine, rifampin, isoniazid, griseofulvin, cimetidine, carbamazepine, phenytoin, and phenobarbital.

And that’s basically the hard part, because I realized the names themselves are simply divided into “quick” names (inducers) and “slow” names (inhibitors).

Of course, you don’t need pictures to recognize that QUICKidine, GRIZZLYofulvin, CARbamazepine, RifAMPin, and PHENPHEN (Phenytoin & Phenobarbital) are “fast” names.

No, I don’t know where the grizzly bear got the illegal drugs. I suspect his dealer was in the car, and the mosquito’s all “Dude, Phenphen isn’t legal. LET ME TAKE CARE OF THAT FOR YOU.”

Similarly, no one should need a poorly-drawn picture to recognize that ICEoniazid, ERRORythromicin, and CEMENTidine are “slow” names.

Why is there a block of cement in the middle of the ice rink? I don’t know. Maybe someone just hates that poor robot.

But then, where would be the fun in that?


30 thoughts on “Memorizing Cyp450 Inducers & Inhibitors

  1. seriously? between the app (i mean, if the justification for getting a sexyphone, i mean a smartphone, was that i’ll have apps i can use for studying and for rotations, then i should probably start getting and using some, right?) and the drawings (which are just EPIC YES), you have completely made my night. and probably boosted my boards score. =)

  2. I, too, accidentally learned something (actually a lot) about cyp450 despite not having a shiny-new-medapps-loaded smartphone :p
    Great mnemonics superbly illustrated. Keep’em coming.

  3. 1. AWESOME. the single best thing you can do while studying for second year is to come up with creative, memorable, graphic and obscene mnemonics. Hat tip: Moonwalking with Einstein, by Josh Foer. Seriously, just spend all of micro drawing cartoons, and you’ll honor (ridiculously simple doesn’t have nearly enough cartoons…)

    2. The two best word-mnemonics for this that I recall from Step 1 Studying are the queen barb mnemonic and SICKAGE (sulfa inh cimetidine ketoconazole acute etOH grapefruit juice erythromycin). But those are boring…and cartoons are not …

    3. That said, as soon as you take care of patients on the floors, you’ll learn that, as a rule, ANYTHING can be a p450 inhibitor or inducer, or both … especially antibiotics … and don’t even get me started on warfarin …



    • This comment is awesome, thanks!

      I so agree with #1. I’ll remember a picture for years, and it’s always so much easier than memorizing words. Makes me wish I had actually bought Moonwalking with Einstein this summer – it was on my summer reading list, and then it just didn’t happen. Maybe during winter break.

  4. AP,

    This is great! Definitely just downloaded the Pharm app on your recommendation. Would it be OK it I stole you cartoons to show on my blog? (Full credit given, of course)


  5. Hi!

    I’m Anni, a pharmacist from Finland, I work in a small hospital in Helsinki. Right now I’m preparing a small lecture for nurses about interactions and medicin administration. It’s quite troublesome theme for them and I try to have some ease in it.

    I ended to wander in Google image search looking for something inspiring about CYP 450-system. Then I saw your drawing about CYP450 inducers with a bear and car and that was something! Now I’m asking if I could show that picture for them in my lecture? Of course I would tell them who has done it.

    I’m as good speaking English than our Formula 1-drivers… maybe it’s our national attribute 


    • Quinidine can both induce and inhibit. Induction is the more important effect according to First Aid.

  6. So just finished my negative marking pharm exam and this literally made me smile everytime they asked me an interaction question because well your drawings in my head, they worked. Thank you!

  7. Just for fun, to expand your mnemonic:
    The guy driving the CARbamazepine is a drunk, because chronic alcohol use also induces.
    The ERROthromycin robot can’t make functioning sperm, and so is sad because he has AZOLESaspermia, as azoles are inhibitors.
    And three points to whoever figures out why there’s grapefruit juice on the ice.

  8. Thanks a lot. I’m a pgy4 psych resident, studying for our yearly exam, PRITE. This made it sink in, though I chaged car to carburetormazepime (carburetors speed up the car, just works for me, in case I ever what the car means, which can happen when you think too, too hard).

  9. may I add SLOWdium Valproate, SSRIs (slow slow reuptake INHIBITORS) fluoxetine and sertraline, and AmiodaDRONE…

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