Background: Azathioprine (AZA) and 6-mercaptopurine (6-MP) are accepted as effective therapy for Crohn's disease and ulcerative colitis. Although general guidelines have been suggested for weightbased dosing of thiopurines, no standard of care has been established. Clinical trials have demonstrated efficacy for weight-based dosing of AZA at 2.5 mg/kg/day and 6-MP at 1.5 mg/kg/day. Escalation of dosing is recommended within 2 weeks of initiating therapy. The aim was to determine the prescribing practices of community practice gastroenterologists with respect to 6-MP/AZA dosing.
Methods:
Questionnaires were distributed via a mail database or during gastroenterology society meetings to gastroenterologists in NY, NJ, and CT. Questionnaires ascertained starting doses of AZA/ 6-MP, use of thiopurine methyltransferase (TPMT) enzyme testing, and strategy for dose optimization.
Results: A total of 145 questionnaires were collected. Twenty-four percent of gastroenterologists escalated the dose within 2 weeks after initiating therapy. The majority used weight-based dosing as their target of therapy. Thirty-five percent reported measuring TPMT levels and 46% used metabolite monitoring.
Conclusions:
Most gastroenterologists take longer than recommended to raise the dose of AZA/6-MP. Although the majority of gastroenterologists reported maximal dosages based on weight, there may be a delay in achieving this goal. Optimizing dosing of AZA/ 6-MP may improve efficacy and reduce the need to use additional therapy.