P344 Short and medium term efficacy of adalimumab in ulcerative colitis – a multicentre, prospective observational study

are particularly at risk for therapy failure. We determined the predictive value of this pharmacological phenomenon in IBD patients. Methods: Clinical effectiveness and tolerability of regular weight-based thiopurine therapy were determined in all IBD patients displaying a skewed metabolism [ratio 6-MMPR/ 6-thioguaninenucleotide (6-TGN) >20]. All samples were routinely assessed between 2008 2012, being part of standard clinical follow-up after initiation of conventional thiopurines. Results: Fourty-one (84%) out of 49 included IBD patients discontinued thiopurines (55% female, 53% with Crohn’s disease and 47% with ulcerative colitis) with a median duration of 14 weeks (IQR 10 29). The majority of patients discontinued thiopurines due to adverse events (55%) or refractoriness (12%). The most commonly observed adverse event was thiopurine induced hepatotoxicity (18 patients, 37%). Median 6-TGN level was 159 pmol/10e8RBC (IQR 113 218 pmol/10e8RBC), median 6-MMPR level was 11020 pmol/10e8RBC (IQR 721