S6373 Dystonia in a Dose: Recognizing a Class Effect in Susceptible Patients

Introduction: Antiemetics are commonly prescribed to manage nausea and vomiting. Still, for a small subset of patients, certain medications in this class can cause severe side effects, including extrapyramidal symptoms like dystonia. This case report describes a young patient who has extrapyramidal side effects to multiple anti-emetics (metoclopramide, promethazine, and prochlorperazine), all of which triggered dystonic reactions, rendering only trimethobenzamide and ondansetron as viable treatment options. Case Description/Methods: A 32-year-old man was admitted to hospital with viral gastroenteritis due to coronavirus infection. The patient was managed on general medical floors with supportive care and as-needed anti-emetics. About fifteen minutes after the administration of metoclopramide, a rapid response was called by the primary nurse due to abnormal posturing and sustained muscle contractions of the neck, back, and bilateral upper extremities. The healthcare team promptly responded, and given characteristic dystonic presentation, prior history of dystonia with other medications, and temporal relation with metoclopramide administration, the reaction was identified as a medication-induced extrapyramidal side effect and diphenhydramine was administered. Five minutes after administration of diphenhydramine, the patient's symptoms improved rapidly, and the dystonic reaction subsided. The patient was monitored for several hours with no recurrence of dystonia. A more comprehensive antiemetic regimen was initiated using trimethobenzamide and ondansetron, which the patient tolerated well. Metoclopramide was added to the patient's adverse reaction list to be avoided in the future. Discussion: This case underscores the importance of recognizing drug-induced dystonia as a potential adverse effect of common anti-emetics, particularly in susceptible individuals. Dopamine antagonism by drugs like metoclopramide, promethazine, and prochlorperazine can induce extrapyramidal symptoms, especially in younger patients who may have a predisposition to these reactions. This case emphasizes the need for healthcare providers to be vigilant and proactive when choosing antiemetic agents, particularly for patients with a history of extrapyramidal symptoms. Further research into strategies to prevent medication-related adverse effects, including enhanced healthcare team education and the integration of clinical decision support tools within electronic medical record systems, would be beneficial.