Toxidromes Part IV Flashcards
What is the mechanism of action of amphetamines and what other drug do they mimic in toxicity?
Sympathomimetic –> toxicity similar to cocaine
What plant is digoxin derived from and what is its mechanism of action?
Foxglove plant –> positive inotrope and negative chronotrope
What clinical symptom is most associated with digitalis toxicity?
Visual disturbances –> yellow/green haze and halo vision
What is the antidote for digoxin overdose and how does it work?
Digibind –> a protein that binds to digoxin and renders it inactive
T/F: Serum digoxin level is essential in measuring the efficacy of treatment for digoxin toxicity.
False: Lab cannot differentiate bound from unbound digoxin. Serum digoxin level useless for 72 hours after Digibind administration.
T/F: Dialysis is an option for treatment in severe digoxin toxicity.
False: Digoxin is too big to be eliminated via dialysis.
What is the best treatment for calcium channel blocker (CCB) overdose?
Supportive care –> ABCs, monitor vitals and ECG
T/F: Administration of calcium is the drug of choice for treatment of CCB overdose?
False: administration of calcium has no impact.
Which drug may be included in the treatment of CCB overdose and why?
Glucagon –> some CCBs cause negative inotropy
Which two calcium channel blockers will cause the most negative inotropy?
Verapamil and diltiazem
Why might iron tablets be a culprit in pediatric ingestions?
They look like M&Ms or Skittles
Because iron is a heavy metal, what treatments for overdose will not be effective?
Charcoal and dialysis will not be effective
What is the mechanism of action of iron toxicity?
Direct corrosive effects on the gastric mucosa and also causes metabolic acidosis by an unknown mechanism.
What are possible clinical sequelae to iron toxicity?
- Early: emesis, bloody diarrhea
- Late: coma, shock, seizure, coagulopathy, hepatic failure, death
What is a long term sequelae of iron toxicity in kids that may persist beyond the recovery period?
Severe scaring of the GI tract resulting in strictures and obstructions.
What is used primarily to diagnose iron toxicity?
Clinical presentation –> Abdominal x-ray may show radiopaque iron pills.
Name and describe the two labs that will be useful in evaluating iron toxicity.
Serum Fe: amount of iron in the blood
TIBC: iron travels in the blood bound to the protein transferrin. If serum Fe is > TIBC, there is free iron in the blood. Free iron is pharmacologically active and can cause toxicity symptoms
What is the antidote for iron toxicity?
Deferoxamine –> IV
How long is deferoxamine administered in iron toxicity?
Deferoxamine turns the urine an orange/pink color s/p chelation of the iron. Deferoxamine is administered until the urine returns to normal color.
T/F: Fat soluble vitamins are more toxic in excess than water soluble vitamins.
True: Excess water soluble vitamins are excreted by the kidneys
Is vitamin toxicity typically due to chronic use or acute overdose?
Chronic Overuse
What are the fat soluble vitamins?
A, D, E, and K
T/F Holly and Mistletoe are toxic to humans?
False: They are toxic to pets –> they cause gastroenteritis in humans but are not lethal
T/F: Silica gel is toxic to humans?
False: it is nothing more than sand
Describe the pathophysiologic affects of black widow spider venom.
It is a neurotoxin leading to influx of Ca and release of Ach
What are the signs and symptoms of a black widow spider bite?
Painful fasciculations and cramping
How do you determine the severity of a black widow spider bite?
The quicker the onset of symptoms, the more severe the reaction will be
Describe the treatment for black widow spider bites?
Wound care, tetanus, calcium gluconate for cramping, anti-venin for patients not responding to conventional therapy
Describe what anti-venin is and how it is derived.
Anti-venin is antibodies to the venom. They are extracted from the animal, then given to a big animal (horse) which makes more antibodies and they are extracted from the large animal for treatment. They can also be made in a lab.
What is the key feature used to identify a brown recluse spider?
Fiddle shaped marking on its back
Describe the S/S of a brown recluse spider bite.
Venom is a potent vasoconstrictor. Causes an area of necrosis in the area of the bite. S/S include a bullseye lesion, pain, burning sensation.
How would you recognize a systemic reaction to a brown recluse spider bite?
Usually occur within 1-2 days of the bite. S/S include fever, chills, malaise, and DIC in worst case scenario
What is the treatment for brown recluse spider bite?
Wound care, tetanus, dapsone within the first 24 hours –> no anti-venin for brown recluse
Which spider bite is more likely to be seen in Kentucky, brown recluse or black widow?
Brown recluse
Name and describe the two broad families of snakes.
Elapidae: rarely bite –> they kill by wrapping themselves around their prey and suffocating them
Crotalidae: aka pit vipers –> kill with venomous bites
What key feature of a snake tends to identify it as more venomous?
Venomous snakes tend to have a more triangular head
T/F: All Crotalidae bites are venomous.
False: not all bites contain venom –> amount and composition of venom varies by time of year
Differentiate polyvalent anti-venin from monovalent.
Polyvalent contains antibodies from several different snakes’ venom in one anti-venin
