P450 Cent

[Haybrant]

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Hi - hope everyone is doing well 🙂

Could someone shed light on a pharm topic. I have learned the P450 inhibitors and inducers thanks to the FA pharm section but there is not a compilation of which drugs/hormones are liver metabolized that will be affected by this.

Maybe my understanding of this topic is lacking: Are the inhibitors of P450 inhibitors because they are being degraded by the liver [and occupying degradation sites], and they would therefore be the drugs that would be broken down faster by the inducers? Or can an inducer induce an inhibitors and vice versa 🙂

also as a side questions: when a virus (say HIV) is latent does that mean that it is only incorporated in the genome and not reproducing at all? or is it synthesizing virus but just hiding (ie in the macrophage, or is it monocyte, w HIV?)

Thanks!

 

[smq123]

Could someone shed light on a pharm topic. I have learned the P450 inhibitors and inducers thanks to the FA pharm section but there is not a compilation of which drugs/hormones are liver metabolized that will be affected by this.

Maybe my understanding of this topic is lacking: Are the inhibitors of P450 inhibitors because they are being degraded by the liver, and they would therefore be the drugs that would be broken down faster by the inducers? Or can an inducer induce an inhibitors and vice versa 🙂

Um, yes - your understanding of the topic is a little off. Your professors at school didn't explain it very well, I take it. (???)

The P450 system is a set of enzymes in the liver that metabolize many, many different drugs. P450 inducers/inhibitors (as well as other substances - ex: grapefruit juice) can either speed up that system of enzymes or slow it down. By doing so, these inducers/inhibitors can change the rate at which drugs are metabolized.

Hopefully that makes sense...

 

[Haybrant]

Um, yes - your understanding of the topic is a little off. Your professors at school didn't explain it very well, I take it. (???)

The P450 system is a set of enzymes in the liver that metabolize many, many different drugs. P450 inducers/inhibitors (as well as other substances - ex: grapefruit juice) can either speed up that system of enzymes or slow it down. By doing so, these inducers/inhibitors can change the rate at which drugs are metabolized.

Hopefully that makes sense...

not sure if you're trying to be condescending for some reason, but thats pretty off base with the question; Maybe your professors abused you. lets let someone else try

bottom line- what major hormones/drugs (ie warfarin, OCPs) are metabolized by the liver that you have to worry about inducers/inhibitor interaction.

 

[smq123]

Could someone shed light on a pharm topic. I have learned the P450 inhibitors and inducers thanks to the FA pharm section but there is not a compilation of which drugs/hormones are liver metabolized that will be affected by this.

Maybe my understanding of this topic is lacking: Are the inhibitors of P450 inhibitors because they are being degraded by the liver [and occupying degradation sites], and they would therefore be the drugs that would be broken down faster by the inducers? Or can an inducer induce an inhibitors and vice versa 🙂

The P450 system is a set of enzymes in the liver that metabolize many, many different drugs. P450 inducers/inhibitors (as well as other substances - ex: grapefruit juice) can either speed up that system of enzymes or slow it down. By doing so, these inducers/inhibitors can change the rate at which drugs are metabolized.

I'm truly sorry if that sounded condescending. It was really because I was confused - your original question was phrased as if you didn't understand how the P450 system works. If that's the case, then I assumed that you hadn't studied it yet - in which case, what are you doing trying to learn it from FA?

bottom line- what major hormones/drugs (ie warfarin, OCPs) are metabolized by the liver that you have to worry about inducers/inhibitor interaction.

Almost anything that is metabolized by the liver will interact with an inducer/inhibitor. This includes oral contraceptives, but also almost any other drug you can think of that isn't renally metabolized. I don't know if there's a specific list of hormones/drugs that you need to worry about - just knowing the inhibitors/inducers seems to be enough.

Maybe I'm still confused by your question...😕

 

[smq123]

bottom line- what major hormones/drugs (ie warfarin, OCPs) are metabolized by the liver that you have to worry about inducers/inhibitor interaction.

http://medicine.iupui.edu/flockhart/table.htm

Is that what you mean?

As you can see, the list of substrates is pretty long. I don't know if it's worth your while to memorize that list.

 

[Haybrant]

alright cool deal, sorry for the over rxn; stressed.

I guess Im curious what accounts for the inhibition and induction of the P450 system. A good part of the boards seems to be memorization but that extra step is often the 'why'

Also, Ive run across qbank/world questions that in affect require an understanding of what drugs will be metabolized by the P450 system. Some drugs are solely excreted by the gall bladder, some by the kidney etc...Maybe FA has it somewhere and im not seeing it.

thanks for the link tho; helpful stuff

 

[PeepshowJohnny]

Well, the inductors are just by increasing the amount of P450 enzyme that the cell has to metabolize. We've all seen that slides of the smooth ER being increased in a cell after giving large amounts of barbituates to a subject. As for the inhibitors, I always just assumed it was just the drug itself acting as an inhibitor, but that's just an assumption and you know what happens when you assume.

 

[Teufelhunden]

http://medicine.iupui.edu/flockhart/table.htm

Is that what you mean?

As you can see, the list of substrates is pretty long. I don't know if it's worth your while to memorize that list.

That site is great, it's just not very digestable. For those of you interested in the neuropsych drugs, this p450 table focuses on those, and groups drugs together by category.

 

[Terpskins99]

That site is great, it's just not very digestable. For those of you interested in the neuropsych drugs, this p450 table focuses on those, and groups drugs together by category.

Talk about digging up the dead.

Anyhow... the First Aid mnemonic should be sufficient for most people.

Inducers
Queen - Quinidine
Barbara - Barbiturates
takes
FenFen - Phenytoin
and
Refuses - Rifampin
Greasy - Griseofulvin
Carbs - Carbamazepine

Inhibitors
Stop - Sulfonamides
Cyber - Cimetidine
Kids - Ketoconazole
from
Eating - Erythromycin
GrapefruitS - Grapefruit juice and St. John's Wart

 

[Doowai]

DO you mean which drugs are hepatically metabolized (like estradiol) and eliminated and which drugs are renally metabolized (like oxandrolone) and excreted?

 

[Terpskins99]

DO you mean which drugs are hepatically metabolized (like estradiol) and eliminated and which drugs are renally metabolized (like oxandrolone) and excreted?

You don't need to know that... though you do need to know which drugs are classically nephrotoxic.

 

[Teufelhunden]

Talk about digging up the dead.

Anyhow... the First Aid mnemonic should be sufficient for most people.

Inducers
Queen - Quinidine
Barbara - Barbiturates
takes
FenFen - Phenytoin
and
Refuses - Rifampin
Greasy - Griseofulvin
Carbs - Carbamazepine

Inhibitors
Stop - Sulfonamides
Cyber - Cimetidine
Kids - Ketoconazole
from
Eating - Erythromycin
GrapefruitS - Grapefruit juice and St. John's Wart

"Digging up the dead?" What do you mean by that? Anyway, I appreciate the mnemonic...never seen that one before. Thanks.

 

[Terpskins99]

"Digging up the dead?" What do you mean by that?

You bumped a post that was over 4 months old.

 

[RustedFox]

FA is incorrect in listing Quinidine as a P-450 inducer.
Lippincott's illustrated Pharmacology, eMedicine, and (gasp) wikipedia all list it as an INHIBITOR of P-450, not an INDUCER of P-450.