A 50-year-old man is brought to the emergency department after developing blurred vision and confusion. Earlier today, he was clearing and burning foliage and weeds on his property. His medical history is insignificant, and he does not take any medications. The patient has no history of illicit drug use. Temperature is 38.9 C (102 F), blood pressure is 110/76 mm Hg, pulse is 120/min, and respirations are 16/min. He is disoriented to time, place, and person. Physical examination shows flushed skin and dry oral mucosa. Both pupils are dilated and nonreactive to light and accommodation. Bowel sounds are decreased. Which of the following drugs can potentially reverse this patient's condition?

Question

A 50-year-old man is brought to the emergency department after developing blurred vision and confusion.  Earlier today, he was clearing and burning foliage and weeds on his property.  His medical history is insignificant, and he does not take any medications.  The patient has no history of illicit drug use.  Temperature is 38.9 C (102 F), blood pressure is 110/76 mm Hg, pulse is 120/min, and respirations are 16/min.  He is disoriented to time, place, and person.  Physical examination shows flushed skin and dry oral mucosa.  Both pupils are dilated and nonreactive to light and accommodation.  Bowel sounds are decreased.  Which of the following drugs can potentially reverse this patient's condition?

Quizplus · Accepted Answer

11ec160b_3c3c_51fb_9249_c5b1e33cfd5c_MD0001_00 This patient with blurred vision, fever, altered mental status, flushed skin, and dry mucous membranes has anticholinergic toxicity, likely from encountering jimsonweed (Datura stramonium) while working in his yard. Jimsonweed contains large concentrations of the anticholinergic compounds atropine, scopolamine, and hyoscyamine. These agents competitively inhibit acetylcholine at the muscarinic acetylcholine receptor, leading to the classic toxidrome summarized above. Anticholinergic toxicity can be counteracted by increasing the concentration of acetylcholine in the synaptic cleft. Physostigmine, a cholinesterase inhibitor, increases acetylcholine levels by preventing its degradation by cholinesterase. (Choice A) Organophosphates are cholinesterase inhibitors that are commonly used as pesticides. Atropine can be used to counteract the effects of excess muscarinic stimulation (eg, increased salivation, miosis, bronchospasm, bradycardia). However, patients remain at risk of paralysis due to nicotinic overactivation, and so also require treatment with pralidoxime, a cholinesterase reactivating agent. (Choices B and D) Benztropine is a centrally acting anticholinergic medication used for the treatment of idiopathic and drug-induced Parkinson disease. Haloperidol is a neuroleptic drug that blocks dopamine receptors in the central nervous system and is used to treat psychosis. These drugs have anticholinergic effects that would worsen this patient's symptoms. (Choice C) Diazepam, a long-acting benzodiazepine, positively modulates GABA_A action by increasing the frequency of chloride channel opening. It is used to treat seizures associated with atropine poisoning but does not affect muscarinic cholinergic receptors. (Choice E) Metoprolol is a selective β1-adrenergic receptor antagonist. It is used to treat angina, acute coronary syndromes, heart failure, hypertension, and arrhythmias. (Choices F and G) Morphine is an opioid pain medication that exerts its effects by stimulating opioid receptors in the brain. Naloxone is a competitive antagonist of these receptors used for opioid overdose. Morphine has some anticholinergic effects and may worsen symptoms whereas naloxone does not affect cholinergic receptors. (Choice I) Thiamine (B₁) is a cofactor for multiple enzymes used in glucose metabolism. Patients who are chronically deficient (eg, due to alcohol use disorder or malnutrition) can develop Wernicke-Korsakoff syndrome (ataxia, ophthalmoplegia, confusion). Educational objective: Anticholinergic agents (eg, atropine, scopolamine) competitively inhibit acetylcholine at the muscarinic acetylcholine receptor. The effects can be memorized with the mnemonic, "Blind as a bat, mad as a hatter, red as a beet, hot as a hare, dry as a bone, full as a flask, and fast as a fiddle," and can be reversed by cholinesterase inhibitors (physostigmine).

A 50-Year-Old Man Is Brought to the Emergency Department After