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Azathioprine Dose Adjustment

6K views 8 replies 2 participants last post by  ath.pantelis 
#1 ·
If a patient on Azathioprine then the dose must be adjusted if he's also taking Allopurinol.
Please explain this concept as am quite confused about it :confused:
 
Discussion starter · #3 ·
What about Mercaptopurine?

OK, let's now talk about Mercaptopurine and Allopurinol.
Is it exactly the same story as Azathiprine and Allopurinol or is there something else playing here?
 
Discussion starter · #5 ·
What makes you believe something else is going on here? The job of xanthine oxidase is to add oxygen subgroups in the purine backbone (hypoxanthine<-->xanthine & xanthine<-->uric acid), regardless of what extras are attached to this backbone.:)
Because Allopurinol and 6MP also blocks PRPP Amidotransferase which is the rate limiting enzyme in purine synthesis. However, in order for them to do that they have to be converted to their nucleotide versions by the action of HPRT.
Add to this that Allopurinol blocks Xanthine Oxidase while 6MP is deactivated by Xanthine Oxidase.
So there's kind of complex interrelations that bugging my head :(
 
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