Toxicology & Antidotes Flashcards
(26 cards)
What is the initial overdose management if the exposure is topical, ocular, or oral?
Topical - remove contaminated clothing and wash skin with sap and water for at least 15 minutes
Ocular - remove contact lenses and rinse eyes with a gentle stream of water for at least 15 minutes
Oral - remove any remaining substances from the mouth. If there are symptoms of burning/irritation, drink a small amount of water or milk immediately
When is activated charcoal most effective and how? What is the dose of activated charcoal? What needs to be done prior to using activated charcoal? When is activated charcoal contraindicated?
Activated charcoal is most useful if used within 1 hour of ingestion. Activated charcoal absorbs as much of the drug as possible while it is still in the gut.
Dose - 1mg/kg (usually only give once)
Prior to using activated charcoal, the airway should be protected to prevent aspiration
Contraindicated if:
- the airway is unprotected (ex. pt unconscious, cannot clear their throat, cannot hold their head upright)
- intestinal obstruction
- GI tract ot intact or if decreased peristalsis
What causes APAP hepatotoxicity? What are the 4 phases of APAP overdose?
Increased metabolism of APAP by CYP450 2E1 to NAPQI (N-acetyl-p-benzoquinone). NAPQI can bind to the liver cell proteins adn cause liver injury.
Phase 1 (1-24 hours): commonly asymptomatic or non-specific symptoms (nausea/vomiting)
Phase 2 (24-72 hours): hepatotoxicity evident on labs (elevated INR, AST/ALT)
Phase 3 (72-96 hours): fulminant hepatic failure (jaundice, coagulopathy, renal failure, and/or death)
Phase 4 (>96 hours): patient recovers or receives a liver transplant
How is an APAP overdose treated?
N-acetylcysteine (NAC) is the antidote. It is a free radical scavenger and precursor to glutathione. Ultimately, GSH increases, which converts NAPQI to non-toxic metabolites.
NAC should be given quickly, preferably within 8 hours and the APAP level (drawn 4-24 hours after ingestion) is used as the basis for treatment. It can be given IV or PO (usually IV)
The APAP level is plotted on the Rumack-Matthew nomogram.
Oral NAC: high dose given once, then lower dose for 17 doses. Repeat dose if emesis occurs w/in 1 hour of administration.
IV NAC: three infusions over a total of 21 hours
What are the symptoms of anticholinergic overdose/poison and what is the treatment?
Symptoms: flushing, dry skin, dilated pupils (mydriasis) and/or blurry vision
Treatment:
- supportive care
- rarely physostigmine is given
What are the reversal agents for:
- apixaban/rivaroxaban
- dabigatran
- warfarin
- heparin/LMWH
apixaban, rivaroxaban - andexanet alfa (Andexxa)
dabigatran - idarucizumab (Praxbind)
warfarin - Kcentra (prothrombin complex concentrate), vitamin K
heparin/LMWH - protamine
What are the symptoms of antipsychotic overdose/poison and what is the treatment?
Symptoms: seizures
Treatment:
- supportive care
- benztropine (if dystonia)
- benzodiazepines if seizures
What is the treatment of benzodiazepine overdose/poison?
Treatment:
- flumazenil (can cause seizures when used in pts taking BZDs chronically)
What is the treatment for CCB and beta blocker overdose?
Beta blockers and CCBs:
- supportive care (fluids, vasopressors)
- glucagon (if unresponsive to supportive treatment)
CCBs:
- IV calcium (chloride or gluconate)
What can cause cyanide overdose/poison and what is the treatment?
Cyanide poison can be due to smoke inhalation, nitroprusside in high doses/long durations/renal impairment.
Treatment:
- hydroxocobalamin (Cyanokit)
What is the treatment for digoxin overdose?
Digoxin immune Fab (DigiFab)
What is a complication of ethanol overdose/poison and what is the treatment?
Ethanol overdose can cause an increased anion gap
If chronic alcohol use suspected: thiamine (vit B1) to prevent Wernicke’s encephalopathy
What are the treatment for 5-fluorouracil (5-FU) or capecitabine overdose/poison?
Uridine triacetate (Vistogard)
What can cause hydrocarbon poisoning? What is important to mitigate?
Hydrocarbon poisoning can be due to petroleum products, gasoline, kerosene, mineral oil, and paint thinners
Must keep patient NPO due to aspiration risk
What are the symptoms of isoniazid overdose/poison and what is the treatment?
Symptoms: seizures, altered mental status
Treatment:
- IV pyridoxine (vit B6) and benzodiazepines
What is the treatment for iron or aluminum poisoning?
deferoxamine (Desferal) - iron and aluminum
What is the treatment for methotrexate poisoning?
- IV sodium bicarbonate (to alkalinize the urine)
- Leucovorin or levoleucovorin (rescue therapy after high-dose cancer therapy)
- Glucarpidase (Voraxaze): rapidly lowers MTX levels in pts with AKI and delayed MTX clearance
What is the treatment for neostigmine or pyridostigmine toxicity?
Pralidoxime: counteracts the muscle weakness and/or respiratory depression secondary to overdose of acetylcholinesterase inhibitors used to treat myasthenia gravis
Atropine or glycopyrrolate can be given to prevent bradycardia from neostigmine
What are the early and later symptoms of nicotine toxicity? What is the treatment?
Early symptoms: abdominal pain, nausea
Later symptoms: bradycardia, dyspnea, lethargy, coma, seizures
Treatment:
- supportive care (atropine for symptomatic bradycardia, benzodiazepines for seizures)
What are the symptoms of organophosphate (OPs) and insecticide poisoning? What is the treatment?
Symptoms: OPs block acetylcholinesterase, which increases acetylcholinesterase, causes cholinergic “SLUDD” symptoms (salivation, lacrimation, urination, diarrhea/defecation)
Treatment:
- atropine (anticholinergic which blocks ACh to reduce SLUDD symptoms)
- pralidoxime (treatment muscle weakness and relieves paralysis of respiratory muscles by reactivating acetylcholinesterase)
- DuoDote (atropine and pralidoxime)
What is the treatment to salicylate poisoning?
Sodium bicarb (alkalinizes the urine, which decreases drug reabsorption and increases the excretion of salicylates)
What is the treatment for toxic alcohol poisoning (ex. ethylene glycol (antifreeze), diethylene glycol, methanol)?
These can cause an increase in anion gap
Treatment
- fomepizole is preferred (if not available, can use ethanol)
What is dangerous about tricyclic antidepressant overdose? What is the treatment?
overdose can cause fatal arrhythmias
Treatment:
- sodium bicarb to decrease a widened QRS complex
- BZDs for agitation/seizures
- vasopressors for hypotension
What is the treatment for valproic acid or topiramate-induced hyperammonemia toxicity?
levocarinitine
