Toxidromes Part IV

Question 1

What is the mechanism of action of amphetamines and what other drug do they mimic in toxicity?

Answer 1

Sympathomimetic –> toxicity similar to cocaine

Question 2

What plant is digoxin derived from and what is its mechanism of action?

Answer 2

Foxglove plant –> positive inotrope and negative chronotrope

Question 3

What clinical symptom is most associated with digitalis toxicity?

Answer 3

Visual disturbances –> yellow/green haze and halo vision

Question 4

What is the antidote for digoxin overdose and how does it work?

Answer 4

Digibind –> a protein that binds to digoxin and renders it inactive

Question 5

T/F: Serum digoxin level is essential in measuring the efficacy of treatment for digoxin toxicity.

Answer 5

False: Lab cannot differentiate bound from unbound digoxin. Serum digoxin level useless for 72 hours after Digibind administration.

Question 6

T/F: Dialysis is an option for treatment in severe digoxin toxicity.

Answer 6

False: Digoxin is too big to be eliminated via dialysis.

Question 7

What is the best treatment for calcium channel blocker (CCB) overdose?

Answer 7

Supportive care –> ABCs, monitor vitals and ECG

Question 8

T/F: Administration of calcium is the drug of choice for treatment of CCB overdose?

Answer 8

False: administration of calcium has no impact.

Question 9

Which drug may be included in the treatment of CCB overdose and why?

Answer 9

Glucagon –> some CCBs cause negative inotropy

Question 10

Which two calcium channel blockers will cause the most negative inotropy?

Answer 10

Verapamil and diltiazem

Question 11

Why might iron tablets be a culprit in pediatric ingestions?

Answer 11

They look like M&Ms or Skittles

Question 12

Because iron is a heavy metal, what treatments for overdose will not be effective?

Answer 12

Charcoal and dialysis will not be effective

Question 13

What is the mechanism of action of iron toxicity?

Answer 13

Direct corrosive effects on the gastric mucosa and also causes metabolic acidosis by an unknown mechanism.

Question 14

What are possible clinical sequelae to iron toxicity?

Answer 14

• Early: emesis, bloody diarrhea

- Late: coma, shock, seizure, coagulopathy, hepatic failure, death

Question 15

What is a long term sequelae of iron toxicity in kids that may persist beyond the recovery period?

Answer 15

Severe scaring of the GI tract resulting in strictures and obstructions.

Question 16

What is used primarily to diagnose iron toxicity?

Answer 16

Clinical presentation –> Abdominal x-ray may show radiopaque iron pills.

Question 17

Name and describe the two labs that will be useful in evaluating iron toxicity.

Answer 17

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

Question 18

What is the antidote for iron toxicity?

Answer 18

Deferoxamine –> IV

Question 19

How long is deferoxamine administered in iron toxicity?

Answer 19

Deferoxamine turns the urine an orange/pink color s/p chelation of the iron. Deferoxamine is administered until the urine returns to normal color.

Question 20

T/F: Fat soluble vitamins are more toxic in excess than water soluble vitamins.

Answer 20

True: Excess water soluble vitamins are excreted by the kidneys

Question 21

Is vitamin toxicity typically due to chronic use or acute overdose?

Answer 21

Chronic Overuse

Question 22

What are the fat soluble vitamins?

Answer 22

A, D, E, and K

Question 23

T/F Holly and Mistletoe are toxic to humans?

Answer 23

False: They are toxic to pets –> they cause gastroenteritis in humans but are not lethal

Question 24

T/F: Silica gel is toxic to humans?

Answer 24

False: it is nothing more than sand

Question 25

Describe the pathophysiologic affects of black widow spider venom.

Answer 25

It is a neurotoxin leading to influx of Ca and release of Ach

Question 26

What are the signs and symptoms of a black widow spider bite?

Answer 26

Painful fasciculations and cramping

Question 27

How do you determine the severity of a black widow spider bite?

Answer 27

The quicker the onset of symptoms, the more severe the reaction will be

Question 28

Describe the treatment for black widow spider bites?

Answer 28

Wound care, tetanus, calcium gluconate for cramping, anti-venin for patients not responding to conventional therapy

Question 29

Describe what anti-venin is and how it is derived.

Answer 29

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.

Question 30

What is the key feature used to identify a brown recluse spider?

Answer 30

Fiddle shaped marking on its back

Question 31

Describe the S/S of a brown recluse spider bite.

Answer 31

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.

Question 32

How would you recognize a systemic reaction to a brown recluse spider bite?

Answer 32

Usually occur within 1-2 days of the bite. S/S include fever, chills, malaise, and DIC in worst case scenario

Question 33

What is the treatment for brown recluse spider bite?

Answer 33

Wound care, tetanus, dapsone within the first 24 hours –> no anti-venin for brown recluse

Question 34

Which spider bite is more likely to be seen in Kentucky, brown recluse or black widow?

Answer 34

Brown recluse

Question 35

Name and describe the two broad families of snakes.

Answer 35

Elapidae: rarely bite –> they kill by wrapping themselves around their prey and suffocating them
Crotalidae: aka pit vipers –> kill with venomous bites

Question 36

What key feature of a snake tends to identify it as more venomous?

Answer 36

Venomous snakes tend to have a more triangular head

Question 37

T/F: All Crotalidae bites are venomous.

Answer 37

False: not all bites contain venom –> amount and composition of venom varies by time of year

Question 38

Differentiate polyvalent anti-venin from monovalent.

Answer 38

Polyvalent contains antibodies from several different snakes’ venom in one anti-venin