Group 2 Flashcards
(21 cards)
What is the source of naloxone?
Naloxone is chemically derived from thebaine, an alkaloid found in the opium poppy (Papaver somniferum).
What is the primary clinical use of naloxone?
It reverses opioid overdose (e.g., respiratory depression) by competitively binding to mu-opioid receptors.
What is the initial IV/IM dose of naloxone for adults?
400 micrograms (0.4 mg) as the first dose.
What is the maximum total naloxone dose for a child (1–11 years)?
2 mg, administered as repeated 100 mcg/kg doses every 1 minute until response.
Why must naloxone be administered cautiously in opioid-dependent patients?
Rapid reversal can trigger acute withdrawal (agitation, vomiting, tachycardia, seizures).
What is the chemical basis of N-acetylcysteine (NAC)?
NAC is a synthetic derivative of L-cysteine, an amino acid found in high-protein foods.
What is the primary antidotal use of NAC?
To prevent liver damage after acetaminophen overdose by replenishing glutathione.
What is the oral NAC dosing regimen for acetaminophen overdose?
- Loading dose: 140 mg/kg.
- Maintenance: 70 mg/kg every 4 hours for 17 doses (total 72 hours).
When is IV NAC preferred over oral NAC?
In patients with altered mental status, GI bleeding, caustic ingestions, or refractory vomiting.
What is the mechanism of activated charcoal?
Adsorbs toxins in the GI tract, preventing systemic absorption.
Which substances are NOT effectively bound by activated charcoal?
Alcohols, acids/alkalis, heavy metals (e.g., iron, lithium), and hydrocarbons.
What is the single activated charcoal dose for adults?
50–100 grams, mixed in water to form a slurry.
Why is activated charcoal contraindicated in unconscious patients?
Risk of aspiration pneumonia if the airway is unprotected.
What is the key limitation of activated charcoal’s effectiveness?
Must be administered within 1 hour of toxin ingestion for optimal effect.
What are common side effects of activated charcoal?
Black stools
Vomiting
Constipation, or diarrhea.
Why is NAC critical within 24 hours of acetaminophen overdose?
Delayed treatment allows toxic metabolite NAPQI to deplete glutathione, causing irreversible liver damage.
What is the IV NAC dosing protocol?
- Loading: 150 mg/kg over 1 hour.
- Second dose: 50 mg/kg over 4 hours.
- Third dose: 100 mg/kg over 16 hours.
What is a contraindication for activated charcoal?
GI perforation or ingestion of non-adsorbable substances (e.g., ethanol).
Why is naloxone used as a diagnostic aid?
Rapid reversal of symptoms (e.g., respiratory depression) confirms suspected opioid overdose.
What is the mechanism of action of naloxone?
Works by competitively binding to opioid receptors, particularly the mu-opioid receptor displacing opioids from the receptors thus reversing the effects of opioids such as respiratory distress.
How does acetylcysteine counteract NAPQI toxicity?
1) Directly conjugates NAPQI. 2) Provides cysteine for glutathione synthesis, restoring glutathione to conjugate NAPQI. Acts as a sulfhydryl group donor.
