A Case of Status Epilepticus Caused by Intravenous Tramadol

Abstract

Tramadol is a recently developed, centrally acting synthetic analgesic agent. The pharmacological mechanism of tramadol has not yet been fully elucidated, but unlike standard opioid analgesics, tramadol alleviates pain by modulating norepinephrine secretion and inhibiting serotonin reuptake [1]. The potency of tramadol is between 10% and 25% of that of morphine at the μ-opioid receptor, so it is considered a “weak opioid.” For this reason, it is regarded as relatively safe. Tramadol has been commonly used for postoperative pain treatment in children who have mild to moderate pain. The recommended dose for the intravenous (IV) route for children is 2 mg/kg every 4 to 6 hours, which is best for analgesic action with minimal side effects [2]. However, tramadol has some unique properties compared to other standard opioid medications that are attributable to its mechanism of inhibiting monoamine reuptake. Examples of the adverse effects of tramadol include respiratory depression, seizure, tachycardia, hypertension, serotonin syndrome, and manic syndrome [3]. Seizures have been noted as a concerning side effect of tramadol since its market approval in the United States in 1995, based on post-marketing reports to the U.S. Food and Drug Administration (FDA). Between 1997 and 2017, 30,730 tramadol-related cases had been reported to the FDA's Adverse Event Reporting System, and seizures accounted for 7% of the cases [4]. The FDA issued a black-box warning in 2017, banning the use of tramadol in children and adolescents under the age of 12, and in those aged 12 to 18 with underlying diseases, due to its potential to cause serious respiratory side effects and death [5]. Despite the FDA’s warning, tramadol continues to be given, which is worrisome. Here, we present a case of tramadol-induced status epilepticus in a 15-year-old girl with no past history of seizures. A 15-year-old girl (height, 159 cm; weight, 47 kg) presented to the emergency department due to abdominal pain. She had normal developmental milestones and her past medical history was unremarkable. She had undergone laparoscopic left ovarian cystectomy (pathology: functional cyst) 23 days earlier. A clinical examination revealed normal hemodynamic variables, and there was no sign of dehydration, or fever. On physical examination, widespread abdominal tenderness without rebound tenderness was found, while other physical examination and lab test results were normal. Abdominopelvic computed tomography (CT) showed paralytic small bowel ileus. She was referred to the gynecology department for conservative management. The patient was given 30 mg of IV ketorolac tromethamine (Trolac, Whanin Pharm Co., Seoul, Korea) and 100 mg of IV tramadol (Tandol, AJU Pharm Co., Seoul, Korea). Since the pain persisted, IV tramadol was