Generic azathioprine vs Imuran

[Maya142]

Title says it all! We have the generic but I've read a couple posts on other sites saying that Imuran is much better than the generic azathioprine.
Thoughts? Anyone here have a preference?

 

[Zeppy321]

Hum interesting I'm on aza too I didn't know Imuran was supposed to be better.

 

[Orchid]

Generic Azathioprine may have inferior absorption characteristics compared to Imuran. It's a thing I've seen repeated on this forum many times and it makes sense to me given what I know about drug synthesis and inactive ingredient interactions. But I have never found or I forgot the study that showed evidence, even with help from Google. I'd love to see it.

Until then, take it with a grain of salt.

 

[Catherine]

I believe DustyKat's kids uses the Imuran. Can't remember why but it made sense and we use the brand name medication.

 

[Juuh]

Same chemical formula, different trade names. How can they be different? Here in Finland first choice from pharmacy is Azamun, and Imuran is the "off-brand" alternative.

I hate 25mg Imuran blister packaging and prefer Azamun packed in container with snap top cap.

 

[DustyKat]

This is an older study Maya but the results are very thought provoking:

Bioavailability of Azathioprine v's Imuran v's 6mp

Abstract

Background:

Azathioprine and 6-mercaptopurine have proven efficacy in the treatment of Crohn’s disease. Immunosuppression is mediated by their intracellular metabolism into active 6-thioguanine metabolites, and clinical responsiveness to therapy in patients with inflammatory bowel disease has been correlated with the measure of erythrocyte 6-thioguanine levels.

Aims and methods:

To perform a dosing equivalency analysis and comparison of clinical efficacy in 82 patients with inflammatory bowel disease on long-term (> 2 months) therapy with either branded azathioprine (Imuran) (n=26), generic azathioprine (n=38), or 6-mercaptopurine (n=18), based on the measurement of erythrocyte 6-thioguanine metabolite levels.

Results:

Disease remission was achieved in 51% (42 out of 82) of patients treated with either azathioprine or 6-mercaptopurine therapy, and correlated well with high erythrocyte 6-thioguanine levels (> 250 pmoles/8 × 108 RBCs). Patients treated with either branded azathioprine or 6-mercaptopurine achieved significantly higher erythrocyte 6-thioguanine levels than patients treated with generic azathioprine, thereby suggesting that branded azathioprine has improved oral bioavailability compared to generic azathioprine. These data are consistent with the putative immunosuppressive role of 6-thioguanine metabolites in the treatment of inflammatory bowel disease, and provides a basis for developing a therapeutic index of clinical efficacy based on the measurement of erythrocyte 6-thioguanine metabolite levels.

Conclusions:

Our results suggest that differences in bioavailability may have clinical relevance when considering the need to optimize erythrocyte 6-thioguanine metabolite levels in patients deemed unresponsive to treatment on conventional drug dosages.

Full Article:
http://onlinelibrary.wiley.com/doi/10.1046/j.1365-2036.2000.00812.x/full

Baesd on this study, and the fact that Matt much prefers the finish on the brand, that is the way we have chosen to go.

Dusty. xxx

 

[Orchid]

Thank you, that was interesting.

I see several problems with their study though, as they mentioned they didn't control patient food intake and Azathioprine/Imuran uptake is known to be sensitive to a wide variety of foods (though not on the scale of say, wafarin, synthetic thyroid hormones and MAOIs), so monitoring patient diet would make this study much stronger. Due to Azathioprine and Imuran themselves having short half lives in the body they're forced to measure a metabolite whose levels vary across patients, and whose levels can respond to the medication in wildly divergent ways. Worst of all, the patients in the study all had IBD of some kind, an illness that as we all personally know, is radically different for every person. Their report says these changes were not observed in healthy volunteers in other studies, which is suspicious at best.

My personal thoughts are that in a perfect world this would lead to more studies but grant money, much like life, is fleeting and trying to justify more interest to lizards in suits would be difficult at best. Given the mess of insurance in America paying for branded drugs out of pocket when a generic exists may not be wise based on one study with so many difficult variables to account for. Though I would suggest based on this information that anyone on Azathioprine/6-MP therapy should stay with the drug brand they started with if it at all possible.

 

[Juuh]

Interesting study for sure! Never thought that there could be any difference. Just wondering who really funded the study and does producer of Imuran have anything to do with it.

I have used mainly Azamun brand (since 2001 or something) but its not available every time I need to get more so then they offer Imuran. Haven't noticed anything different, just the packaging that annoys me

 

[Lady Organic]

I tried Imuran in 2011 and my GI insisted I took Imuran and not the generic. He mentionned the original had greater efficacy.