Group 11 Flashcards
(30 cards)
What class of drugs does atropine belong to, and what is its primary mechanism of action?
Anticholinergic class; competitively inhibits acetylcholine at muscarinic receptors, reducing parasympathetic activity.
Name three causes of cholinergic toxidrome that atropine can reverse.
Organophosphate/carbamate insecticides, muscarine-containing mushrooms, and pilocarpine/choline esters.
What is the initial IV dose of atropine for organophosphate poisoning, and how is it titrated?
1–2 mg IV initially; doubled every 5–10 minutes until secretions dry and oxygenation improves.
What are the endpoints for atropine therapy in organophosphate poisoning?
Resolution of excessive bronchial secretions and symptomatic bradycardia.
List three adverse effects of high-dose atropine.
Severe tachycardia, delirium, fever.
How does sodium thiosulfate detoxify cyanide?
Acts as a sulfur donor, converting cyanide to thiocyanate via the enzyme rhodanese.
What is the adult dose of sodium thiosulfate for cyanide poisoning?
50 mL slow IV, administered after sodium nitrite infusion.
What monitoring is required after sodium thiosulfate administration?
Monitor oxygenation, perfusion, and recurrent cyanide toxicity signs for 24–48 hours.
What is the role of pralidoxime in organophosphate poisoning?
Reactivates acetylcholinesterase by cleaving the phosphate bond formed with organophosphates.
Why must pralidoxime be given early in organophosphate poisoning?
It is ineffective after the enzyme-organophosphate complex “ages” (>24 hours post-exposure).
What is the adult maintenance infusion rate for pralidoxime in severe cases?
500 mg/hour or 8 mg/kg/hour IV.
Name two nicotinic symptoms pralidoxime addresses and two muscarinic symptoms atropine targets.
Nicotinic (pralidoxime): Muscle weakness, fasciculations. Muscarinic (atropine): Bronchorrhea, bradycardia.
What are the contraindications for sodium thiosulfate?
None
Why is atropine tapered gradually after prolonged high-dose use?
To prevent recurrence of cholinergic symptoms upon abrupt discontinuation.
What adverse effect can occur if pralidoxime is administered too rapidly?
Hypertension or transient worsening of symptoms (e.g., muscle rigidity).
Which carbamate insecticides may not respond to pralidoxime?
Carbaryl.
What is the pediatric dose range for pralidoxime?
20–50 mg/kg IV (max 2 g per dose).
What is a rare but notable adverse effect of sodium thiosulfate?
Black, tarry stools or bone pain.
What route is used for pralidoxime in field settings without IV access?
IM/SC (e.g., autoinjector).
What is the key limitation of pralidoxime in aged organophosphate poisoning?
Inability to reactivate acetylcholinesterase once the enzyme-organophosphate complex becomes irreversible.
What paradoxical effect can occur if atropine is injected too slowly or at a very low dose?
Paradoxical bradycardia (due to initial stimulation of vagal nuclei).
What specific enzyme does sodium thiosulfate work with to detoxify cyanide?
Rhodanese (converts cyanide to thiocyanate).
What is the maximum pediatric dose of sodium thiosulfate?
50 mL (regardless of weight).
What symptom indicates that atropine dosing is sufficient in organophosphate poisoning?
Drying of tracheobronchial secretions and ability to oxygenate the patient.
