Dr Miles Sparrow and colleagues from Illinois described the use of allopurinol in azathioprine /mercaptopurine nonresponders.
The research team assessed the ability of the treatment to shunt metabolism of mercaptopurine toward thioguanine, and improve clinical responses.
The team assessed 20 outpatients who were azathioprine/mercaptopurine nonresponders, and had high methylmercaptopurine metabolite levels.
Subjects were commenced on allopurinol 100 mg daily.
The team reduced the original dose of mercaptopurine/azathioprine by 25% to 50%.
|Mayo Scores decreased from 4 to 3 points in ulcerative colitis|
|Clinical Gastroenterology and Hepatology|
The researchers observed that after allopurinol was started, mean thioguanine levels increased from 191 to 400 pmol/8 × 108 red blood cells.
In contrast, mean methylmercaptopurine levels decreased from 10,600 to 2000 pmol/8 × 108 red blood cells.
The addition of allopurinol led to a reduction in the mean partial Harvey Bradshaw Index in Crohn's disease patients from 5 to 2 points.
The research team found that mean Mayo Scores decreased from 4 to 3 points in ulcerative colitis patients.
The team identified that the addition of allopurinol enabled a reduction in mean daily prednisone dosage from 17 to 2 mg.
The researchers noted that it lead to normalization of transaminase levels, with mean aspartate aminotransferase levels reducing from 43 to 24 IU.
In addition, the team found that the mean alanine aminotransferase levels reduced from 102 to 34 IU.
Dr Sparrow's team commented, “The addition of allopurinol to thiopurine nonresponders with high methylmercaptopurine metabolite levels is an effective and safe means of optimizing thioguanine production.”
“The additional treament leads to improved disease activity scores, reduced corticosteroid requirements, and normalization of liver enzymes."