Rapid improvement in post-infectious gastroparesis symptoms with mirtazapine

We report the case of a 34-year-old woman with severe post-infectious gastroparesis who was transferred from an outside medical facility for a second opinion regarding management. This patient had no prior history of gastrointestinal symptoms. However, in the aftermath of a viral illness, she developed two months of intractable nausea, vomiting, and oral intake intolerance that resulted in numerous hospitalizations for dehydration and electrolyte disturbances. A solid-phase gastric emptying scan had confirmed delayed emptying, confirming gastroparesis. Unfortunately, conventional pro-kinetic agents and numerous anti-emetic drugs provided little or no relief of the patient's symptoms. At our institution, the patient experienced a cessation of vomiting, reported a significant reduction in nausea, and tolerated oral intake shortly after taking mirtazapine. Based on mirtazapine's primary action as a serotonin (5-HT) 1a receptor agonist, we infer that this receptor system mediated the clinical improvement through a combination of peripheral and central neural mechanisms. This report highlights the potential utility of 5-HT1a agonists in the management of nausea and vomiting. We conclude that mirtazapine may be effective in treating symptoms associated with non-diabetic gastroparesis that are refractory to conventional therapies.