FA16 mistake? Allopurinol comp inhibitor of XO

[ZKenpachi]

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Hello,

In FA16 page 448, it says that allopurinol is a comp inhibitor of XO. Dr Turco from Kaplan said it is a non comp inhibitor, even drew a Lineweaver-Burk plot and everything.

I did some googling, and it says allopurinol is a suicide inhibitor, which seems like a form of non comp inhibition.

Also checked official and user submitted errata, and it's not there.

Anyone can tell for sure?

 

[Phloston]

Hello,

In FA16 page 448, it says that allopurinol is a comp inhibitor of XO. Dr Turco from Kaplan said it is a non comp inhibitor, even drew a Lineweaver-Burk plot and everything.

I did some googling, and it says allopurinol is a suicide inhibitor, which seems like a form of non comp inhibition.

Also checked official and user submitted errata, and it's not there.

Anyone can tell for sure?

https://books.google.co.jp/books?id=XnPOEEeXXnYC&pg=PA159&lpg=PA159&dq=allopurinol+inhibitor+reversible&source=bl&ots=q53WhwOzrp&sig=A62v1WsHpceLbSfltdRz3t2mE34&hl=en&sa=X&ved=0ahUKEwiwkunoiavQAhXLvbwKHTkWBjQ4ChDoAQgxMAQ#v=onepage&q=allopurinol inhibitor reversible&f=false

P. 159 in this text says allopurinol is reversible. In the broader literature, I have seen both.

I don't have the FA16 in front of me at this moment to verify directly, but if the text lists competitive, rather than both, I would say that it's OK to leave as is because the initial inhibition by allopurinol is in fact competitive. It is only after xanthine oxidase converts allopurinol to its metabolite, alloxanthine, that we see 'suicide' non-competitive inhibition. That is, allopurinol doesn't directly have non-competitive inhibitory effect until it's converted to a form that's no longer even the original drug. I was an editor for FA15 and would have kept the entry as is here.

 

[ZKenpachi]

That makes sense. Thank you!

 

[Phloston]

大丈夫！No problem!

 

[Goldchains]

so kaplan is BS? like you could have mistake because of that doctor Turco

 

[Phloston]

My thought would be that perhaps the focus was on the graphic representation of non-competitive inhibition in general, rather than strictly, this is what you have to memorize for allopurinol. But perhaps that drug was mentioned as an example.

 

[Transposony]

大丈夫

Real man ?