Toxidromes Intro Dr. Peters (video) Flashcards
What are Toxidromes?
Set of symptoms seen in toxicities of specific drug classes
What is the MOA Benzo Toxicities and what does it cause in a patient?
binding to GABA receptors ->
profound inhibitory effect of GABA on neuronal excitation
CNS depression
-lorazepam, diazepam, temazepam, oxazepam, midazolam
What is the antidote of Benzos and how does it work? What is the dose?
Flumazenil
-0.2 mg IV push
-competitively and permanently binds to GABA receptors and pushes BZD off the receptors
When should Flumazenil be avoided as an antidote?
patients who take Benzos regularly
-GABA receptors are sensitive to Benzos, when displacing Benzos from the receptors it can induce seizures
-may use supportive care instead -> airway management (intubation)
What is the MOA of opioid toxicity?
binding to opioid receptors in the brain
-can lead to CNS and respiratory depression
What is the antidote of Opioids?
What is the recommended dose?
Naloxone
-IV, IM initial dose: 0.4-2mg
-IN dose: 1 mg in each nostril
-continuous infusion rate: 2/3 of the total hourly intermittent dose (example they took 1 mg of IV or IN -> take 0.6 mg/hr)
When would a continuous infusion of Naloxone be considered?
if the patient ingested XR opioids or if they respond to naloxone but fall asleep again (probably due to long-acting opioid)
Continuous infusion starting ratec=
(total hourly intermittent dose)(2/3)
What are the Toxidromes of sympathomimetics?
-Hyperthermia
-Hypertensive, tachycardia
-Mydriasis (dilated eyes)
-Diaphoresis (sweating)
Sympathomimetic drugs
-Cocaine
-Methamphetamine/Amphetamines (illicit and Rx)
-Theophylline, Caffeine
-Spice/K2, bath salts
What is the supportive care approach in Hyperthermia/Diaphoresis and Hyperactive delirium?
Hyperthermia/Diaphoresis:
-cooling, chilled fluids, room temperature reduction, ice packing
Hyperactive delirium: Benzos
1st line: lorazepam or midazolam
2nd line: haloperidol or droperidol
cautious with restraints: it can cause rhabdomyolysis -> renal failure (induced by myoglobin in the blood)
How are hypertension and tachycardia in sympathomimetic toxicities managed?
1st line:
treat the underlying agitation with benzos + cold fluids
2nd: pharmacologic
use a non-selective BB like labetalol (avoid selective ß-blockers like metoprolol bc they don’t block alpha receptors)
What is a symptom of Cocaine toxicity?
Cocaine chest pain: cocaine-induced myocardial vasospasm (ischemia)
-it mimics an acute MI (ST elevation seen in the EKG)
-usually no long-lasting complications
What are drugs that are seen with anticholinergic toxicity?
-Diphenhydramine (benadryl)
-TCAs
-Cyclobenzaprine (skeletal muscle relaxant)
-Atropine (antimuscarinic)
Common symptoms of Anticholinergic Toxicity?
Blind as a bat: visual disturbance
Dry as the desert: dry mouth
Mad as a hatter: agitation
Red as a beet: flushing
Hot as hell: Hyperthermia
Other symptoms of Anticholinergic toxicity?
-Anticholinergic delirium
-Tachycardia
-Urinary retention
-Flushed skin
-Dilated pupils (they can’t constrict their pupils, keep the room dark)
-Dry membranes
-cardiac channel effects: sodium channel blockade prolonged QRS (primary cause of mortality) !!!
What are symptoms of Anticholinergic delirium?
-Carphologia (picking at clothes, and other stuff)
-softened mumbled speech
-difficult verbalization
-visual halluciantion
What is the primary mortality cause of Anticholinergic toxicity?
prolonged QRS by blocking fast sodium channels
-affect phase 0 of QRS: it takes longer for Na+ to get into myocardial tissues
-> QRS prolonged
How should QRS prolongation be managed in Anticholinergic toxicities? What is the goal QRS?
Hypertonic solution with a high concentration of sodium to compensate for the sodium blockade
-goal: QRS < 100 ms
-Sodium Bicarbonate
1-2 mEq/kg
-Sodium acetate
1-2 mEq/kg
-Hypertonic saline (3% NaCl)
250 ml over 30 min
What is the dose of Benzos for agitation in Anticholinergic toxicities?
1-2 mg IV push PRN
What is an antidote for Anticholinergics?
Physostigmine salicylate
-blocks ACh???
-reversible anticholinergic inhibitor
1-2 mg IV push over 5-10 minutes
What happens if Anticholinergic antidotes are given too rapidly?
seizures and bradycardic arrest
When should Antidotes of Anticholinergics be used?
-if the only manifesting symptom is delirium
-if delirium causes harm to the patient or the staff
What can be used if an anticholinergic antidote causes a seizure or seizures caused by anticholinergic toxicity?
-1 mg atropine
-short-acting Benzo (midazolam, triazolam)
Which drugs are contraindicated to treat seizures induced by anticholinergic toxicity?
Phenytoin/fosphenytoin
-they act as class 1b antiarrhythmics
-they can cause further QRS prolongation and cardiac arrest
Which drugs may be considered if Benzos don’t work for seizures?
GABA inhibitors
-propofol with intubation
-barbiturates (phenobarbital or pentobarbital coma)
