Testing for Azathioprine

[Mehita]

Is there a specific test that can determine how much my son is actually absorbing Azathioprine?

We know he is at therapeutic levels already, but his TPMT was intermediate. Could he be at therapeutic levels without the Aza doing anything for him? Like it's metabolizing to fast or something? Or maybe not metabolizing at all?

His last 6-TGN was 272 (range 230-400) and his 6-MMPN was 642 (anything under 5700 is good). The 6-TGN in range means the Aza should be working, right?

He's been flaring for about a month and is now on pred again. Just trying to figure out where we are in the grand scope of things.

Thoughts?

 

[Catherine]

My best guess would be that he needs to be higher in the range for it to work.

How long has he been a therapeutic levels? Maybe it needs more time.

Maybe this will of interest.

http://www.healio.com/gastroenterol...6-a430-d735ef89a8d7}/how-do-you-monitor-patie

 

[Mehita]

Thanks, Catherine. He's been therapeutic for two months now and flaring for one of those months.

 

[Catherine]

I know aza is good for keeping in remission but not good for getting into remission. Maybe he needs something to kick him to a strong remission amd then the aza will be able to keep him there.

 

[alex_chris]

Azathioprine is effective if blood tests show that the white blood cell count is at 4.0 or slightly below or slightly above (3.5 to a maximum of 5.0) for a prolonged period of time (no massive swings between blood tests).

Lowing the WBCC is the main therapeutic effect azathioprine has, so if this measure is not where it should be over many months, the azathioprine dosage should be adjusted.

However, note, as mentioned above, that azathioprine is not a drug that helps much in inducing remission. Azathioprine is a drug that helps MAINTAIN remission. If he has been on aza for 2 months and has been flaring for one of those, then the aza just can't help - because first, it takes at least 2-3 months for it to really be effective (and even longer if the dosage isn't correct - it should be at 2mg to 2.5mg per kg bodyweight) and second, as said above azathioprine helps with remission, it doesn't really help with inducing it.

 

[Mehita]

On May 10th, he started the Aza and prednisone for a flare. By June 10th he had normal labs, was at therapeutic levels, was feeling great and was off pred. Since then, his WBC has been dropping, but not as low as you suggest, alex_chris. Prior to Aza he always hovered around 12 and now he's down to 7.1, so maybe with a dose adjustment it might drop a little more?

We started at 1.5mg per kg because of the intermediate TPMT. Bumping up to 2mg seems reasonable then, right?

His GI nurse mentioned Remicade the last time we talked and I just wonder if we've given Aza a fair chance.

 

[Catherine]

How much does he weight? Is his current dose 37.5 mg per day?

Had he taken his daily dose before the aza levels were done?
Were they done on a 25 mg day or 50 mg day?

Maybe Aussie or Dusty would know?

 

[Mehita]

He's about 85 lbs now and takes 25mg one day, 50mg the next. Not sure what he took the day of the labs but it would have been a good 18 hours prior since he takes his Aza before bed.

 

[Catherine]

Please check my calculations:-

85 lb = 38.5 kgs

On his 25 mg day he is taking 0.65 mg per kg

On his 50 mg day he is taking 1.30 mg per kg.

 

[Aussie]

Hi Catherine and Mehita, the TGN level is just within the therapeutic range, although I would suggest increasing the dose and rechecking the TGN and MMP levels in 1 month, aim for a TGN around 400+.

AZA usually takes around 3 months to start working, although you have to give at least 6 months before you can really rule out a response.

It sounds like your son was on Prednisone for 1 month (from May to June) and then subsequently started flaring after stopping the prednisone. He really needs to either start EEN or go back on the prednisone for a good 2 to 3 month course, at which time the AZA should be kicking in. Common to flare if the prednisone is withdrawn too quickly (one month course while waiting for AZA to start is too short).

Best wishes.

 

[Johnnysmom]

My son was on Prednisone for 3 months while taking the 6mp. The first month was full 40mg dose and then the next 2 months was tapering. So we had a full three months of coverage from prednisone before the 6mp had to do its job. It still took many months after that to have fecal cal normal so I think you can still see things improve over time.

Also, they don't want to suggested it, I think because they are afraid about compliance but you might want to ask the GI about just giving your son a 3/4 of a pill everyday instead of 1/2 one day and whole the next. Your cutting them anyways, and I think it keeps the levels more consistent in his body. My GI was all for it once I suggested it. Although I am sure it's not that big of a deal if so many GI's do it that way, it just made me feel a bit better to have the dose the same.

(((Hugs))))