Page 104 - JCBP-3-1

Journal of Clinical and

Basic Psychosomatics

CASE REPORT
Serotonin syndrome induced by the combined

use of metaxalone, phentermine, and
duloxetine: A case report

Gabrielle Rivera-Maldonado 1 , Wenxin Song 2 , Leenil Noel 2 ,
and Adam J. Fusick 1,2,3 *
1 Department of Psychiatry and Behavioral Neurosciences, University of South Florida Morsani
College of Medicine, Tampa, Florida, United States of America
2 Department of Psychiatry and Behavioral Neurosciences, University of South Florida Morsani
College of Medicine, Tampa, Florida
3 Mental Health and Behavioral Sciences Service, James A. Haley Veterans Hospital, Tampa, Florida,
United States of America

Abstract

Serotonin syndrome is a potentially life-threatening condition caused by increased
serotonergic activity. Although this condition is commonly associated with certain
antidepressants, this report describes a case of serotonin syndrome induced by the
combined use of metaxalone and phentermine with duloxetine and bupropion. Our
*Corresponding author: patient developed serotonin syndrome following the administration of metaxalone
Adam J. Fusick for severe back spasms. Symptoms resolved following the discontinuation of
(adam.fusick@va.gov) these medications, provision of supportive care, and administration of lorazepam
Citation: Rivera-Maldonado G, and cyproheptadine. This case report adds to the existing literature, as studies on
Song W, Noel L, Fusick AJ. metaxalone-induced serotonin syndrome are currently limited. This case report also
Serotonin syndrome induced by highlights the importance of monitoring polypharmacy, especially when prescribing
the combined use of metaxalone,
phentermine, and duloxetine: less common medications such as metaxalone as well as weight-loss medications
A case report. J Clin Basic such as phentermine.
Psychosom. 2025;3(1):98-102.
doi: 10.36922/jcbp.4490
Received: August 10, 2024 Keywords: Serotonin syndrome; Serotonin toxicity; Metaxalone; Phentermine; Selective
serotonin reuptake inhibitors; Polypharmacy
1st revised: August 29, 2024
2nd revised: October 16, 2024
Accepted: October 29, 2024 1. Introduction
Published Online: November 20,
2024 Serotonin syndrome is a toxic condition resulting from the overuse of one or more
1
Copyright: © 2024 Author(s). serotonergic drugs, which increases neurological serotonergic activity. Its clinical
This is an Open-Access article manifestations exhibit a spectrum of severity proportional to levels of free serotonin.
distributed under the terms of the Mild-to-moderate symptoms include hyperreflexia, tremors, and gastrointestinal
Creative Commons Attribution
License, permitting distribution, disturbances, whereas severe cases may result in profound autonomic hyperactivity,
and reproduction in any medium, mental status changes, and sustained clonus/rigidity. Serotonin syndrome is often
2
provided the original work is 3
properly cited. diagnosed using a set of clinical indicators known as Hunter’s criteria.
Publisher’s Note: AccScience The most common etiology is the combined use of selective serotonin reuptake
Publishing remains neutral with inhibitors (SSRIs) or serotonin–norepinephrine reuptake inhibitors (SNRIs) with
regard to jurisdictional claims in
published maps and institutional monoamine oxidase inhibitors (MAOIs), followed by the use of two MAOIs or other
affiliations. types of serotonergic polypharmacy. Combining medications with diverse mechanisms

Volume 3 Issue 1 (2025) 98 doi: 10.36922/jcbp.4490