Use of mirtazapine in functional vomiting

To the Editor,

Functional Vomiting is defined as recurrent, unexplained vomiting at least once per week that is not cyclical and lacks an organic basis. Stress and psychosocial factors can act as modulators via the brain–gut axis to influence clinical presentation and outcome, which suggests that the association between functional vomiting and psychosocial aspects needs to be further recognized and investigated (Levy, 2008).

Mirtazapine is a noradrenergic and specific serotonergic antidepressant. It has been proved to be effective and tolerable in the treatment of depression with its unique pharmacological profile by blocking the post synaptic 5HT-2 and 5HT-3 receptors and pre-synaptic α-2 auto-receptors and by stimulating 5-HT1 receptor. We are reporting a case of functional vomiting who responded well to low doses of mirtazapine.

Mrs A, a 35-year-old female was referred to psychiatric clinic with symptoms of nausea and vomiting over the past 3 months from Gastroenterology department. Her magnetic resonance imaging (MRI) brain was normal, upper gastrointestinal (UGI) endoscopy revealed oesophagitis, there was electrolyte imbalance due to vomiting and other investigations were normal. When the patient was interviewed, the symptoms of depression were present, and according to Diagnostic and Statistical Manual of Mental Disorders–Fourth Edition (DSM-IV), the diagnosis of major depressive disorder (MDD) was made. The patient was started on mirtazapine 7.5 mg and was gradually increased to 15 mg. After 1 week of mirtazapine, the nausea and vomiting had reduced, and over a period of 3 weeks, the vomiting had stopped.

Several psychiatric disorders are widely believed to have a major role in functional gastrointestinal disorders (FGIDs) in adult and young populations. It has been suggested that a link exists between anxiety and the gastrointestinal tract. There are reports showing the efficacy of mirtazapine as an effective antiemetic agent in adult patients related to depression (Pae, 2006), non-mechanical vomiting after gastric bypass, chemotherapy-related nausea and vomiting, treatment-resistant hyperemesis gravidarum and postoperative nausea and vomiting. Mirtazapine’s antiemetic effect may be explained due to its antagonism of 5-HT3 receptors (Coskun, 2011).

A timely psychiatric consultation may help to identify and treat possible psychiatric disorders and prompt psychopharmacological treatment of unremitting vomiting. Mirtazapine could be a treatment option in these subjects particularly in the presence of anxiety/depressive disorders. Further well-designed, placebo-controlled studies with larger samples are needed on this topic.