Mark Malamood, Aaron Roberts, Rahul Kataria, Henry P Parkman, Ron Schey

Gastroparesis symptoms can be severe and debilitating. Many patients do not respond to currently available treatments. Mirtazapine has been shown in case reports to reduce symptoms in gastroparesis. To assess the efficacy and safety of mirtazapine in gastroparetic patients. Adults with gastroparesis and poorly controlled symptoms were eligible. Participants were prescribed mirtazapine 15 mg PO qhs. Questionnaires containing the gastrointestinal cardinal symptom index (GCSI) and the clinical patient grading assessment scale (CPGAS) were completed by patients' pretreatment, at 2 weeks, and at 4 weeks. Primary end point was nausea and vomiting response to mirtazapine using the GCSI. Secondary end point was nausea and vomiting severity assessment using the CPGAS. P-values were calculated using the paired two-tailed Student's t-test. Intention to treat analysis was used. A total of 30 patients aged 19-86 years were enrolled. Of those, 24 patients (80%) completed 4 weeks of therapy. There were statistically significant improvements in nausea, vomiting, retching, and perceived loss of appetite at 2 and 4 weeks (all P-values <0.05) compared with pretreatment. There was a statistically significant improvement in the CPGAS score at week 2 (P=0.003) and week 4 (P<0.001). Of the total patients, 14 (46.7%) experienced adverse effects from mirtazapine and due to this, 6 patients stopped therapy. Mirtazapine significantly improved both nausea and vomiting in gastroparetics after 2 and 4 weeks of treatment. Side effects led to treatment self-cessation in a fifth of patients. From these data, we conclude that mirtazapine improves nausea and vomiting, among other symptoms, in patients with gastroparesis and might be useful in select patients.