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Naltrexone therapy for Crohn's disease and ulcerative colitis.

To the Editor: In the April edition of Journal of Clinical Gastroenterology, Dr Smith et al1 published a randomized, placebo-controlled study of low-dose naltrexone therapy for Crohn’s disease. Naltrexone was used as sole therapy in children with moderate-to-severe Crohn’s disease. Therapy was safe and clinical improvement was demonstrated as evidenced by statistically significant reduction in CDAI and improvement in quality of life scores. Two prior publications from this group focused on adults with Crohn’s disease, and LDN was used as adjunctive therapy.2,3 The double-blind study showed statistically significant clinical and endoscopic healing.3 A fourth study in the literature was a case report showing success in a child with duodenal Crohn’s disease.4 Neuropeptides (eg, enkephalins and endorphins) are present in the gastrointestinal tract and modulate immune responses.5,6 Upregulation of met-enkephalin (opioid growth factor) and opioid receptors can be induced by a rebound effect from administration of short-acting, low-dose naltrexone.7 Higher levels of endogenous opioids and receptors inhibit cell proliferation, which suppress B-lymphocyte and T-lymphocyte responses.8,9 Naltrexone acts to reverse a mouse colitis model by decreasing proinflammatory interleukins 6 and 12.10 In light of the Crohn’s disease naltrexone literature and similar clinical experience, LDN was prescribed as adjunctive therapy to adults with moderate-to-severe ulcerative colitis who failed or had partial response to mercaptopurine and/or infliximab in a clinician’s practice. Questionnaires were administered as part of routine follow-up. Adverse events were evaluated. Preliminary evidence for clinical efficacy was determined by selfassessed questionnaires. Positive responses included “markedly or moderately improved.” Failed responses were “mild help,” “temporary help,” “not helped,” or “withdrew due to side effects.” A retrospective chart review was performed. Twelve patients received naltrexone 4.5mg/d. Duration (mean±SD) of naltrexone treatment was 46±75 weeks (maximum, 270wk). One patient withdrew after 8 weeks owing to insomnia. Positive clinical responses were reported in 6 of 12 patients. Two clinical responders had colonoscopy before and after naltrexone and each had complete mucosal healing. Adjunctive low-dose naltrexone appears to be effective in some ulcerative colitis patients who are failing conventional therapy. A double-blind study is required owing to a high placebo rate in ulcerative colitis.11