DLA5- Toxicology (environment, occupational)

Question 1

(1) are the mechanisms of CO poisoning

(2) is the treatment for CO exposure

Answer 1

1:

• tightly binds Hb (more than O2), blocks O2 delivery
• binds Fe –> inhibits cytochrome enzymes in oxidative phosphorylation (ETC)

2- 100% O2 administration + hyperbaric chamber

Question 2

ethanol:

• (1) overdose presentation
• (2) Tx

Answer 2

1- CNS depression, hypoglycemia (impaired gluconeogenesis)

2:

• maintain vital signs
• prevent aspiration of vomit
• IV dextrose for hypoglycemia
• Thiamine for Wernicke-Korsakoff
• electrolyte correction

Question 3

describe process of methanol poisoning

Answer 3

• metabolized into formaldehyde + formic acid
• formic acid –> severe acidosis, retinal damage, blindness
• GI distress, SOB, LOC / coma
• death via respiratory cessation

Question 4

describe methanol poisoning Tx

Answer 4

• fomepizol or ethanol to compete with methanol metabolism
• IV sodium bicarbinate for metabolic acidosis
• hemodialysis

Question 5

Antifreeze = (1):

• (2) clinical presentation with ingestion
• (3) Tx

Answer 5

1- ethylene glycol

2- metabolized into toxic aldehydes / oxalate –> severe acidosis and renal damage

3:

• fomepizol or ethanol to compete with metabolism
• IV sodium bicarbonate for metabolic acidosis
• hemodialysis

Question 6

(1) is used to treat insecticide poisoning

(2) may also be given if early enough, describe brief mechanism

Answer 6

Atropine (anti-muscarinic):
-note organophosphates and carbamate inhibit AChE

Pralidoxime- breaks bond or insecticide with AChE

Question 7

(1) is a common rodenticide, (2) is Tx for ingestion

Answer 7

1- warfarin

2- vitK OR fresh-frozen plasma

Question 8

CN has high affinity binding for (1) commonly found in (2) in the body. (3) are the resulting symptoms and mechanisms of CN poisoning.

Answer 8

(cyanide)
1- binds ferric iron (Fe3+)
2- heme group in cytochromes in mitochondria

3- lactic acidosis, cytotoxic hypoxia –> convulsions and death via hyperventilation

Note- acute exposure usually is survived

Question 9

list the agents found in Cyanide Antidote kit

Answer 9

1) Amyl Nitrite Pearls + Sodium Nitrite –> Hb into methemoglobin allowing competition and upstarts ETC
2) Sodium Thiosulfate –> helps CN metabolism into thioncyanate for elimination

3) methylene blue –> methemoglobin back to Hb
4) hydroxy-cobalamin –> cyano-cobalamin –> urinary excretion

O2 therapy is not too helpful

Question 10

Pb poisoning Tx:

• (1) for seizures
• (2) for cerebral edema
• (3) for chelation

(4) for organic Pb poisoning

Answer 10

1- diazepam
2- mannitol and dexamethasone

3- IV Edetate Calcium Disodium; IM dimercaprol, oral succimer, IV unithol

4- symptomatic, chelation only works on inorganic Pb

Question 11

Arsenic poisoning Tx:

• (1) is Tx for acute inorganic poisoning
• (2) is Tx for chronic inorganic poisoning
• (3) is Tx for Arsine gas poisoning

Answer 11

1:

• supportive via H2O, electrolytes
• chelation via IV unithiol, IM dimercaprol, oral succimer

2- IM dimercaprol

3- n/a –> Sxs = massive hemolysis => Hb deposition and renal failure

Question 12

Hg poisoning Tx:

• (1) for acute exposure
• (2) for chronic exposure

Answer 12

1- chelators: oral/IV unithiol, IM dimercaprol, oral succimer

2: kinda unknown
- unithiol, succimer will inc elimination but effects are unknown
- dimercaprol will redistribute Hg to CNS —- AVOID

Question 13

______ is chelator of choice is acute Fe poisoning

Answer 13

Deferoxamine

Question 14

______ is commonly effective as adsorbent for most toxins, but doesn’t bind Fe, so not used in Fe poisoning

Answer 14

activated charcoal

Question 15

determine chelator by route of administration:

• (1) succimer
• (2) dimercaprol
• (3) unithiol

Answer 15

1- oral
2- IM
3- IV, oral