Which of the following is the most likely cause of this patient’s condition?
This patient presents to the Emergency Department with a depressed mental status and normal sized pupils after an unknown toxic ingestion. Many different agents can act as Central Nervous System depressants and cause this clinical presentation. Some examples include ethanol, toxic alcohols (methanol, ethylene glycol, isopropyl alcohol), benzodiazepines, barbiturates, opioids, and muscle relaxants.
Of the choices listed, Heroin (Choice A) and Alprazolam (Choice B) are the most likely. Heroin is an opioid, and Alprazolam is a benzodiazepine (a sedative-hypnotic agent). The clinical presentation caused by overdoses of opioids versus sedative-hypnotic agents overlaps in many areas, but the pupillary exam can help the most in differentiating the type of ingestion. Opioids will can constricted, pinpoint pupils, while benzodiazepines should not cause change in pupillary size. See the chart below for a review of the most common toxidromes (toxic syndromes).
Cocaine (Choice C) is a sympathomimetic with a CNS excitatory effect, not a CNS depressant effect as in this patient. A large ingestion of paracetamol (Choice D) is often accompanied with little to no symptoms in the first 24hours. Later in the ingestion timeline, liver failure and its associated sequalae can occur if no antidote is given. Correct Answer: B