A 19-year-old woman is brought to the emergency department by her father with complaints of trembling of her hands, excessive sweating, and confusion. Her symptoms began 3 hours ago and have progressively increased. She also had an episode of diarrhea an hour ago. The father reports that his daughter had been to the pharmacy a few hours before her symptoms began, but he does not know what she purchased. Past medical history is significant for depression, for which she takes sertraline every morning. She does not drink alcohol or use drugs. Vital signs are temperature 40.3°C (104.5°F), blood pressure 134/83 mmHg, pulse 137 beats/min, and respirations 19/min. On physical examination, she is not oriented to time or place but is oriented to person (recognizes her father) There is diffuse muscular rigidity, and patellar reflexes are +4. On auscultation of the abdomen, increased bowel sounds are heard. The patient is given oxygen by a nasal cannula, intravenous fluids and intravenous diazepam.
Intake of which of the following drugs is likely to have precipitated the patient’s condition?
B) Dextromethorphan
This patient probably has serotonin syndrome, suggested by the rapid onset of classic clinical features of altered mental status, autonomic instability (diaphoresis, hyperthermia, tachycardia, and hypertension), and neuromuscular hyperactivity (muscle rigidity, hyperreflexia). Serotonin syndrome is caused by an excess of serotonin (5-hydroxytryptamine [5-HT]) or 5-HT receptor activation. It is usually precipitated by the simultaneous intake of two or more serotonergic drugs, but it can also occur after the initiation of a single serotonergic drug in a susceptible individual. Its treatment primarily involves supportive care and benzodiazepines, as was given to this patient. This patient is already on a serotonergic drug, sertraline, a selective serotonin reuptake inhibitor (SSRI). Dextromethorphan is a cough medication that can increase serotonin levels and can cause serotonin syndrome if combined with another serotonergic drug such as an SSRI.
Answer choice A: Calcium docusate, is incorrect. Calcium docusate is used as a laxative to relieve constipation. Although intake of docusate could explain one the patient’s symptoms (diarrhea), it wouldn’t be expected to cause altered mental status, autonomic instability, or neuromuscular hyperactivity.
Answer choice C: Fexofenadine, is incorrect. Fexofenadine is a second-generation anti-histaminie used for allergies. It does not significantly affect serotonin levels and is not typically associated with serotonin syndrome.
Answer choice D: Ibuprofen, is incorrect. Ibuprofen is a nonsteroidal anti-inflammatory drug (NSAID) used to relieve pain and reduce inflammation. Although it can have mild effects on serotonin metabolism, it is rarely known to cause serotonin syndrome.
Answer choice E: Omeprazole, is incorrect. Omeprazole is a proton pump inhibitor (PPI) used to reduce gastric acid secretion. They do not directly affect serotonin levels and are not typically associated with serotonin syndrome.
Key Learning Point
Serotonin syndrome is characterized by the classic triad of altered mental status, autonomic instability and neuromuscular hyperactivity. It is usually caused when two serotonergic drugs are taken together.
