A rare case of combined strychnine and propoxur toxicity from a single preparation

To the Editor:

Strychnine is a naturally occurring alkaloid derived from the seeds of the Strychnos nux-vomica tree that continues to be used in various pesticides and traditional remedies around the world. The hallmark of strychnine poisoning is convulsions with lucid mental status. Propoxur (2-isopropoxyphenyl N-methylcarbamate) is a carbamate pesticide and insecticide that is also commercialized as a rodenticide. Patients present with cholinergic symptoms such as increased salivation, urinary incontinence, diarrhea, and emesis. We report a case of a patient who presented with propoxur and strychnine toxicity from ingestion of a single preparation and highlight the difficulties involved with diagnosis in a patient presenting with this mixed clinical picture.

A 36-year-old Cambodian man ingested a handful of a plant-like mixture in a self-harm attempt 30 min prior to arrival in the emergency department. His symptoms were vomiting, drooling, muscle twitching, and trismus. Vital signs were: Temp, 36.7°C; HR, 118 bpm; BP, 137/87 mmHg; RR, 18/min; O₂ sat, 98% RA. On exam, he was alert and oriented x 3 and pupils were 4 mm bilaterally and reactive. He had facial fasciculations and increased rigidity in the lower extremities. The patient reported ingestion of a pesticide that he had imported from Cambodia called “kroup slang.” Organophosphate poisoning was presumed based on the patient's cholinergic presentation and the Southeast Asian origin of the preparation where organophosphate poisoning is more common. After administration of atropine 6 mg, the drooling subsided. Pralidoxime 2 g bolus and 500 mg/h infusion was then started. The patient's muscle spasms and rigidity responded to diazepam 10 mg and midazolam 30 mg. Further investigation via a Cambodian interpreter suggested this mixture was not “kroup slang” but a preparation marketed as a pesticide that contained the strychnine-containing compound known as “slang nut.” He subsequently underwent intubation, orogastric lavage, and administration of activated charcoal. The patient was admitted to the ICU and sedated with propofol 5 mcg/kg/min and lorazepam 2 mg every 2 h. Pralidoxime was discontinued on hospital day #1. While in the ICU, the patient's rigidity improved, sedation was tapered, and he was extubated on hospital day #3. LC/MS analysis identified the substance as strychnine 3200 ppm and the carbamate, propoxur 0.270 ppm.

This patient presented with symptoms that were initially presumed to be secondary to an organophosphate exposure. Further investigation revealed a strychnine-containing product that was more consistent with the patient's clinical presentation. Fruits of the Strychnos nox vomica tree are commonly referred to as “slang nuts” and are used as remedies for gastrointestinal illnesses. There are several reports of toxicity in the Cambodian population using strychnine-containing remedies.^1,2 Patients typically present with initial stiffness of the face and neck followed by overall muscle rigidity. In between spasms, the muscles can become relaxed.¹ Prompt recognition of strychnine poisoning is vital to prevent deterioration and death.^3,4 This case was especially difficult because of the mixed clinical picture as well as the lack of initial interpreter information. Physicians should be aware that this combination of poisons exists and the resulting mixed clinical picture can lead to difficulties with diagnosis of these two toxicities.