Long term outcome of using allopurinol co-therapy as a strategy for overcoming thiopurine hepatotoxicity in treating inflammatory bowel disease.

Department of Gastroenterology, Guy's ad St Thomas' Hospitals, London, UK.

Background Hepatotoxicity results in the withdrawal of thiopurines drugs, azathioprine (AZA) and mercaptopurine (MP), in up to 10% of patients with inflammatory bowel disease. Our group has previously demonstrated that allopurinol with AZA/ cyclosporin/ steroid 'triple therapy' improved renal graft survival Aim To confirm the hypothesis that allopurinol may alleviate thiopurine hepatotoxicity by similar mechanisms as proposed in our renal study. Methods Unselected patients with acute thiopurine hepatotoxicity were offered allopurinol co-therapy with low dose AZA or MP. The starting AZA/MP dose was determined by TPMT activity (2 patients were intermediate TPMT), then this dose was reduced to 25% for allopurinol co-therapy. Response to treatment was assessed by clinical severity indices, endoscopy and blood tests. Results Of 11 patients (3 Crohn's disease, 8 ulcerative colitis) treated, 9 (82%) remain in long-term remission (median: 42 months) with normal liver tests. One patient also successfully bypassed flu-like symptoms. Two stopped: 1 nausea, 1 abnormal liver function (steatosis on biopsy). Leucopenia occurred in two cases and resolved with minor dose reductions. Conclusions. Allopurinol co-therapy with low-dose AZA/MP can alleviate thiopurine hepatotoxicity. It appears safe and effective for long-term use, but requires monitoring for myelotoxicity. Assessing the TPMT activity helps tailor the AZA/MP doses.

PMID: 18616642 [PubMed - as supplied by publisher]