1590 Another Case of Duloxetine-Induced Lymphocytic Colitis

Abstract

INTRODUCTION: Microscopic colitis comprises two histologic subtypes; Collagenous colitis (more severe) and Lymphocytic colitis (LC). The pathogenesis is unclear but likely multifactorial with some associations to smoking and diseases with autoimmune background. Potential causative drugs have also been implicated with the most common being NSAIDS, PPI and Selective serotonin-reuptake inhibitors (SSRI). We are reporting a case of Duloxetine, a selective serotonin and norepinephrine-reuptake inhibitor (SNRI), causing LC. CASE DESCRIPTION/METHODS: A 49 yo F, caucasian with PMH of GERD and recent diagnosis of fibromyalgia was referred to gastroenterology clinic for diarrhea of unexplained origin for 1 month. Patient claimed diarrhea began 6 weeks after starting Duloxetine. She reported around 5 episodes of explosive watery, brown bowel movements daily with bloating. She also endorsed fatigue, dizziness and joint pains. She denied fevers, chills, blood in the stools, abdominal pain, nausea, vomiting. She denied any recent travel, new food trial, sick contact, new medications other than Duloxetine. She didn't use NSAIDs or PPI. Her other home medications were Levothyroxine and Lisinopril. Her symptoms of upper body pain, loss of energy and mood swing had improved considerably, and her rheumatologist doubled the dose of Duloxetine and the patient noted that the number of daily bowel movements increased. Physical exam showed hyperactive bowel sounds and colonoscopy revealed a completely normal colon. The pathology of the biopsy taken reported diffuse mixed colonic inflammation, marked intraepithelial lymphocytosis and focal acute cryptitis favoring lymphocytic colitis with no evidence of collagenous colitis. Infectious etiologies were ruled out. Decision was made to taper the Duloxetine, and patient was started on Loperamide. Upon follow-up visit two months later, pt reported complete resolution of the diarrhea, but recurrence of her fibromyalgia symptoms for which she was given cyclobenzaprine, which seemed to be have helped. DISCUSSION: Lymphocytic colitis is often insidious but sudden onset was reported in forty percent of patients. There were two other published case reports of duloxetine-associated LC, and just like this case, discontinuation of the medication resulted in prompt resolution of the diarrhea. Microscopic colitis has been associated with excessive fluid loss and malabsorption caused by the inflammation and can easily result in dehydration, dizziness and weight loss affecting quality of life.