What do we need to know about p450 what are some pneumonics?

[ej37]

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When I asked the four kids I was studying for theirs, they all listed Quinidine as an enhancer...

so it seems like yet again FA has done everything a pretty big disservice creating a mneumonic with false info. Not to mention some of the ones they put in their seemed more for "completeness" sake than relevance.

How is the USMLE going to test this? What interactions do I have to know? Katzung book has waaay too many to remember...

 

[21CentSouldier]

When I asked the four kids I was studying for theirs, they all listed Quinidine as an enhancer...

so it seems like yet again FA has done everything a pretty big disservice creating a mneumonic with false info. Not to mention some of the ones they put in their seemed more for "completeness" sake than relevance.

How is the USMLE going to test this? What interactions do I have to know? Katzung book has waaay too many to remember...

there was a uworld question that had a nice summary table of 450 inhibs/inducers.

hmmm can't find it, i'm pretty sure i had a question on it.

 

[kstreet]

Inhibitors

Right-O, Quin — INHIBIT yourself from drinking a KEG of quinolones and chloramphenicol because it will make you Acutely Very SICk

Ritonavir
Omeprazole
Qunidine

Ketoconazole
Erythromycin
Grape Fruit

Fluroquinoloes
Chloramphenicol

Acute EtOH

Valproate

Sulfanomides
Isoniazid
Cimetidine



Inducers

Barb-E Steals Smokin Phen, INDUCES vomiting, and Refuses Greasy Gluttonous Carbs Chronically

Barbituates
Ethosux

St. Jons Wort

Smoking

Phenytoin

Rifampin

Griseofluvin

Glucocorticoids

Carbamazepine

Chronic EtOH




Not the best ones out there, but they'll do.

 

[RySerr21]

When I asked the four kids I was studying for theirs, they all listed Quinidine as an enhancer...

so it seems like yet again FA has done everything a pretty big disservice creating a mneumonic with false info. Not to mention some of the ones they put in their seemed more for "completeness" sake than relevance.

How is the USMLE going to test this? What interactions do I have to know? Katzung book has waaay too many to remember...

😕

"Quinidiine can both induce and inhibit different isoforms of P-450. Induction is the most important effect." It even lists Quinidine in the enhance/inducer column.

Thats straight from FA....the mnemonic in FA is correct, and its all that you need to know. The mnemonics the poster listed above or just slightly modified versions of what is in FA.

 

[jkuk]

The DIT guys gives the following two mnemonics, they arent super great but they help me:

Inducers: (BCGPQRS) - i know its just a bunch of letters, but it helped me
Barbiturates
Carbamazepine
Griseofulvin
Phenyotin
Quinidine
Rifampin
St. Johns Wort

Inhibitors: PICKEGS

Protease Inhibitors
Isoniazid
Cimetidine
Ketoconazole
Erythromycin
Grape Juice
Sulfonamies

 

[raynor123456]

"Barb" likes "Carb's" and "Greasy foods". So, she takes "Phen-Phe"n because she wants to look like a "Queen". But she also "drinks chronically", her lifestyle has INDUCED depression so she needs to "revamp" her diet to include an herbal remedy with "St. John's Wart."

Barbiturates
Carbamazepine
Griseofulvin
Phenyotin
Quinidine
Chronic Alcohol
Rifampin
St. Johns Wort

Being a "Pro-tease" "is no ez-task kid". You've got to give in to "earthly sin", "grab" your "self", and "acutely" INHIBIT "kreepy azz-holes" from "seeing (C-ine)" you.

Protease inhibitors
Isoniazid
Erythromycin
Grape Juice
Sulfonamides
Acute alcohol
Ketoconazole
Cimetidine

 

[unsung]

Haha, I did the same thing. I made a story:

"Really depressed guy kills himself story by barbituates. RIP." = (+) CYP450 (Picture a cross or ambulance.)

Guy is really depressed so he tries (St. John's Wort), which doesn't work. This makes him more depressed, so he (smokes) and becomes a (chronic alcoholic).

His substance use & bad habits damage his brain, and he starts having seizures, so he takes more drugs (Phenytoin, Carbamazepine, Ethosuximide).

Seizures gone, still depressed. Decides he'd be happy as an athlete and takes steroids (glucocorticoids), but he ends up getting a fungal infection (Griseofulvin)... and leprosy (Rifampin).

He's fed up and overdoses on (barbituates). RIP.


...Yeah, the story doesn't hold up to inspection (don't think too hard re: steroids lol), but I remember it! 😉

 

[raynor123456]

If you want to fix your story, just say "and takes steroids. Unfortunately, he took the wrong kind (glucocorticoids) and ends up with a fungal infection and leprosy."

Ha, ha. I like it overall though ^_^ I may have to steal it!

 

[ej37]

Hey guys. I guess my first post wasn't clear as people are still confused.

QUINIDINE DOES NOT INDUCE P450. IT is an INHIBITOR. Therefore it is more like a protease inhibitor than an anti-seizure. Both FA and DIT are wrong, as are the mnemonics in this thread.


Sorry for creating confusion here, just trying to help.


http://www.jbc.org/content/280/46/38617.abstract

 

[raynor123456]

Hey guys. I guess my first post wasn't clear as people are still confused.

QUINIDINE DOES NOT INDUCE P450. IT is an INHIBITOR. Therefore it is more like a protease inhibitor than an anti-seizure. Both FA and DIT are wrong, as are the mnemonics in this thread.


Sorry for creating confusion here, just trying to help.


http://www.jbc.org/content/280/46/38617.abstract

FA specifically says it does both. For that reason, I imagine it's unlikely we'll get it on step 1 unless quinidine is provided as the only answer of the bunch that "changes" P450. I've also read that the inducing effect is typically the more important of the two.

 

[ScubaStarved]

FWIW, UWorld QID 1777 has the list that its authors think most important. I touched on some I felt are relevant in another thread, but that 1777 adds FQs and Ritonavir to the inhibitor list from FA and leaves Quinidine out altogether.

One could reasonably add SSRIs and Omeprazole to the list of inhibitors without too much effort, but I doubt it'll get you any points.