Mercaptopurine treatment should be considered in azathioprine intolerant patients with inflammatory bowel disease.
BACKGROUND
Adverse drug reactions are a significant reason for therapeutic failure during thiopurine treatment of inflammatory bowel disease. Some smaller series in this patient population have shown that a switch to mercaptopurine may be successful in many cases of azathioprine intolerance.


OBJECTIVE
To assess the long-term outcome of mercaptopurine treatment in a large patient population with azathioprine intolerance.


METHODS
We identified 135 patients (74 women; median age 40 years) with Crohn's disease (n = 88) or ulcerative colitis (n = 47) and reviewed their medical records.


RESULTS
A total of 70 patients (52%) tolerated mercaptopurine and were followed up for 736 (362-1080) days; 65 patients discontinued mercaptopurine due to adverse events after 25 (8-92) days. Mercaptopurine was tolerated in 71% (12/17) with hepatotoxicity and in 68% (13/19) with arthralgia/myalgia during azathioprine treatment. Previous abdominal surgery was more common in mercaptopurine intolerant patients [39/65 (60%) vs. 27/70 (39%); P = 0.02] and thiopurine methyltransferase activity was higher in mercaptopurine tolerant patients than in mercaptopurine intolerant patients [13.2 (11.4-15.3) vs. 11.8 (9.6-14.2) U/mL red blood cells; P = 0.04; n = 81].


CONCLUSIONS
A trial of mercaptopurine should be considered in azathioprine intolerance, as half of the patients tolerate a switch to mercaptopurine. Patients with hepatotoxicity or arthralgia/myalgia during azathioprine treatment might benefit more often than those with other types of adverse events.
Hindorf
U
U
Department of Gastroenterology and Nutrition, University Hospital, Lund, Sweden. ulf.hindorf@skane.se
Johansson
M
M
Eriksson
A
A
Kvifors
E
E
Almer
S H C
SH
D000328:Adult; D001379:Azathioprine / Q000009:adverse effects*; D004305:Dose-Response Relationship, Drug; D004342:Drug Hypersensitivity; D005260:Female; D006801:Humans; D007166:Immunosuppressive Agents / Q000627:therapeutic use*; D015212:Inflammatory Bowel Diseases / Q000188:drug therapy*; D008297:Male; D015122:Mercaptopurine / Q000627:therapeutic use*; D008875:Middle Aged; D016896:Treatment Outcome
D007166:Immunosuppressive Agents; D015122:Mercaptopurine; D001379:Azathioprine