Adverse events leading to discontinuation or dose reduction of thiopurine therapy occur in 9% to 28% of patients with inflammatory bowel disease (IBD).
Dr Hindorf and colleagues from Sweden evaluated the influence of thiopurine methyltransferase status and thiopurine metabolites in IBD.
The researchers assessed the effect of these therapies in a large patient population for the risk of developing adverse events.
The team identified 364 patients with IBD and present or previous thiopurine therapy from a local database.
The researchers observed adverse events in 34% of patients.
Adverse events were more common in adults than children, and in low to intermediate than normal thiopurine methyltransferase activity.
The team noted that myelotoxicity developed later than other types of adverse events.
|Mercaptopurine therapy may be considered in azathioprine-intolerant patients|
|Alimentary Pharmacology & Therapeutics|
An increased frequency of adverse events was observed in patients with tioguanine nucleotide above 400.
The researchers also identified more adverse events in patients with methylated thioinosine monophosphate above 11,450 pmol/8 × 108 red blood cell.
A shift to mercaptopurine was successful in 48% of azathioprine-intolerant patients.
In addition, the team found a successful shift to mercaptopurine in all cases of azathioprine-induced myalgia or arthralgia.
Dr Hindorf's team concluded, “A pre-treatment determination of thiopurine methyltransferase status might be appropriate as patients with low to intermediate thiopurine methyltransferase activity are more prone to develop an adverse event.”
“Determination of metabolite levels can be useful in the case of an adverse event.”
“Mercaptopurine therapy should be considered in azathioprine-intolerant patients.”