How are Azathioprine and 6-mercaptopurine dosed by gastroenterologists? Results of a survey of clinical practice

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http://www3.interscience.wiley.com/cgi-bin/abstract/117868128/ABSTRACT?CRETRY=1 & SRETRY=0

Original Article

How are Azathioprine and 6-mercaptopurine dosed by gastroenterologists? Results of a survey of clinical practice

S. Yip, MD 1, Mark Woodward, PhD 1, T. Abreu, MD 1, Miles P. Sparrow, MD 2 *

1Mount Sinai School of Medicine, New York, NY, USA2Department of Gastroenterology, Box Hill Hospital, Melbourne, Australia

email: Miles P. Sparrow (miles.sparrow@...)

*Correspondence to Miles P. Sparrow, Department of Gastroenterology, Box Hill Hospital, Melbourne, , 3128 Australia

Keywords

Crohn's disease • ulcerative colitis • azathioprine • 6-mercaptopurine • metabolite levels • thiopurine methyltransferase

Abstract

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 weight-based 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.

(Inflamm Bowel Dis Volume 14, Issue 4 , Pages 514 - 518, 2007)

Received: 11 June 2007; Accepted: 23 October 2007

Digital Object Identifier (DOI)10.1002/ibd.20345