Serotonin Syndrome Induced by Fluvoxamine and Mirtazapine

OBJECTIVE: To document a case of serotonin syndrome associated with the combined use of fluvoxamine and mirtazapine, and to discuss the pharmacodynamic and pharmacokinetic interactions that were the likely causes of this potentially serious adverse drug reaction (ADR). CASE SUMMARY: A 26-year-old white woman with a 12-year history of anorexia nervosa was being treated with fluvoxamine. After mirtazapine was added to her therapy, she developed tremors,restlessness, twitching, flushing, diaphoresis, and nausea,symptoms that are consistent with serotonin syndrome. DISCUSSION: The possible causes of this ADR are discussed, including the effects of fluvoxamine and mirtazapine alone, the possible pharmacodynamic and pharmacokinetic interactions of these two drugs, and the patients underlying anorexia nervosa. CONCLUSIONS: An increasing number of drugs that affect serotonin are available and are indicated for various disorders. Since there is a significant likelihood of these agents being prescribed concomitantly, clinicians must be aware of possible interactions that could lead to serotonin syndrome.