70 - Toxicology II

Question 1

What are the receptor competitor therapies?

Answer 1

• Warfarin
• Opioids
• Competitive receptor antagonists (naloxone, naltrexone)

Question 2

What is warfarin?

Answer 2

Anticoagulant that interferes with synthesis of vitamin K-dependent coagulation factors

Question 3

What are the adverse symptoms of warfarin?

Answer 3

Adverse symptoms include hemoptysis, excessive bruising, bleeding from nose or gums, or blood in urine or stool

Question 4

How do you treat bleeding and high INR due to warfarin?

Answer 4

Requires reversal by injection of vitamin K (phytonadione), or (in case of severe bleeding) prothrombin complex or fresh frozen plasma infusion to replace coagulation proteins

Question 5

What are the opioids that are receptor competitors?

Answer 5

Heroin, morphine, meperidine, codeine, etc.

Question 6

Describe the action of naloxone

Answer 6

Naloxone (Narcan®, Nalone®, and Narcanti®)

• Acts at µ, κ, and δ receptors to competitively block/reverse the effects of opiates
• Duration of action: ~45 minutes

Question 7

Describe how naltrexone is different than naloxone

Answer 7

Naltrexone (Revia®)

• Same action as naloxone
• Longer duration of action (24-72 hrs) than naloxone
• Can also be used in withdrawal treatment

First use naloxone to save their life within minutes, then give naltrexone for maintenance to treat poisoning so the effects of the opioids don’t come back

Question 8

What is methemoglobinemia?

Answer 8

• State in which the heme iron is in the Fe+3 state (ferric), and not Fe+2 (ferrous) of normal hemoglobin
• Methemoglobin, is unable to transport oxygen ***

Question 9

What causes methemoglobinemia?

Answer 9

Caused by exposure to various chemicals (nitrites, sulfa drugs, many others)

Question 10

What is the anecdote used to treat methemoglobinemia?

Answer 10

Methylene blue

Question 11

How does methylene blue work?

Answer 11

Mechanism of Action: causes a direct chemical reduction of methemoglobin back to hemoglobin

Question 12

What are toxidromes?

Answer 12

Toxidromes are common, and often well-characterized, clinical syndromes that provide a symptomatic fingerprint allowing for the successful recognition of patterns of poisoning associated with specific intoxicants

This means that in the ER, you see a certain set of symptoms, and you can match the toxidrome to the presenting patient in order to determine the cause of poison

Not “bullet proof” or 100%, but it gives you a good idea

Question 13

What are the most prevalent clinical toxidromes?

Answer 13

• sympathomimetics
• sedative hypnotics
• opioids
• anticholinergics
• cholinergics
• tricyclic antidepressants (TCAs)
• salicylates
• acetaminophen

Question 14

Describe the symptoms and cause of a sympathomimetic toxidrome

Answer 14

Cause = CNS stimulant (cocaine, amphetamines, PCP)

Pupils = mydriasis

Other = hypertension, tremor, hyperthermia

Question 15

Describe the symptoms and cause of a sedative/hypnotic toxidrome

Answer 15

Cause = CNS depressants (alcohol, barbiturates, benzodiazepines)

CNS = coma

Respiration = decreased

Pupils = miosis or mydriasis

Other = hypotension

Question 16

Describe the symptoms and cause of a opioid/opiate toxidrome

Answer 16

Cause = opiates, morphine, codeine, propoxyphene, oxycodone, hydrocodone

CNS = coma (decreased consciousness)

Respiration = depression

Pupils = “pinpoint” miosis

Other = hypothermia, hypotension, “opiate triad”, histamine release

Question 17

Describe the symptoms and cause of a anticholinergic toxidrome

Answer 17

Cause = anticholinergics, antidepressants

CNS = agitation

Pupils = mydriasis

Other = fever, dry skin, flushing, urinary retention [hot, dry, mad, red, blind] ***

Question 18

Describe the symptoms and cause of a cholinergic toxidrome

Answer 18

Cause = organophosphates/carbamates and other insecticides, nicotine

Pupils = “pinpoint” pupils (PPP)

Other = SLUDE - everything is wet

Question 19

Describe the symptoms and cause of a tricyclic antidepressant toxidrome

Answer 19

Cause = TCAs (amitriptyline; imipramine; desipramine)

CNS = coma, agitation

Pupils = mydriasis

Other = dysrhythmia, convulsions, hypotension (due to alpha blockade)

Question 20

Describe the symptoms and cause of a salicylate toxidrome

Answer 20

Cause = ASA, aspirin, other salicylates

Respiration = can increase or normal

Other = diaphoresis, tinnitis, agitation, alkalosis (early), acidosis (late), hyperpyrexia

A little less defined than some of the others

Question 21

What are some of the other frequently encountered toxicants?

Answer 21

• Acidic substances (cleaners)
• Alkaline substances (cleaners)

In general, monitor ABCs and dilute with water to neutralize

Question 22

How do you treat benzodiazepine poisoning?

Answer 22

Rarely fatal unless taken with ETOH or other CNS depressant due to synergistic CNS depression

Receptor antagonist: flumazenil

Question 23

How do you treat acetaminophen poisoning?

Answer 23

Acetaminophen poisoning occurs after the depletion of glutathione - can result in hepatic necrosis, death due to hepatic failure

N-acetylcysteine (Mucomyst®) to restore glutathione

Question 24

How do you treat cocaine overdose?

Answer 24

Cocaine overdose leads to cardiac dysrhythmias leading to cardiac arrest

Treat the dysrhythmia with lidocaine and monitor ABCs

Question 25

How do you treat opiate overdose?

Answer 25

Main signs are bilateral miosis (PPP) and HR/respiratory depression and arrest

Treat with naloxone

Question 26

How do you treat a meperidine overdose (an opioid)?

Answer 26

You will see dilated pupils due to antimuscarininc effects and increased HR

Treat with naloxone

Question 27

What is the last “interesting toxicant”?

Answer 27

Dioxin

Prime minister of Ukraine was poisoned this way