Toxicology

Question 1

what is cyproheptadine used for and its mechanism

Answer 1

5-HT2 antagonist used for serotonin syndrome

Question 2

treatment for opioid poisoning

Answer 2

• opioid antagonist: naloxone and nalmefene

- IV sodium bicarbonate

Question 3

seen with severe acute intoxication of theophyllines

Answer 3

seizures

hypotension and ventricular arrhythmias

Question 4

associated with chronic intoxication of theophylline

Answer 4

cardiac dysrhythmias

Question 5

drugs given for symptomatic hypoglycemia seen with sulfonylurea and meglitinides

Answer 5

IV dextrose and octreotide

• octreotide: decreases calcium influx hence decreases insulin release
• giving dextrose will cause an increase in glucose which triggers insulin release so octreotide tries to prevent some insulin release so hypoglycemia isn’t triggered again

Question 6

how to manage neuroleptic syndrome caused by antipsychotics

Answer 6

• discontinue antipsychotics

- treat with dantrolene and bromocriptine

Question 7

what is methanol metabolized to

Answer 7

formaldehyde and formic acid

Question 8

how does formic acid toxicity present

Answer 8

severe acidosis, retinal damage, and blindness

Question 9

treatment of methanol

Answer 9

Fomepizole - alcohol dehydrogenase inhibitor

ethanol - higher affinity for alcohol dehydrogenase than methanol

Question 10

what is ethylene glycol oxidized to

Answer 10

toxic aldehydes and oxalate (get calcium oxalate acid)

Question 11

treatment for ethylene glycol

Answer 11

fomepizole and ethanol

Question 12

what are the insecticides and their general mechanism

Answer 12

Organophosphates
Carbamates

anticholinesterase inhibitors

Question 13

specific mechanism of organophosphates and how ingestion manifests

Answer 13

phosphorylates acetylcholinesterase therefore inhibiting it

• DUMBELS - diarrhea, urination, miosis and muscle weakness, bronchospasms, excitation, lacrimation, salivation and sweating
• also target neuropathy target esterases

Question 14

treatment of organophosphate poisoning

Answer 14

atropine

pralidoxime: splits the phosphate-enzyme bond and can regenerate new cholinesterase

Question 15

mechanism of carbamates

Answer 15

inhibits acetylcholinesterase by carbamoylation of its active site

Question 16

how do you treat carbamates

Answer 16

atropine and pralidoxime

Question 17

how does cyanide work in terms of its actions in the body

Answer 17

high affinity for iron in the ferric state –> binds to Fe3+ in heme of cytochrome a,a3 in mito –> prevents O2 from serving as final electron acceptor

Question 18

treatment for cyanide poisoning

Answer 18

• large pool of ferric iron
• cyanide antidote kit
• cyanokit

Question 19

what is in the cyanide antidote kit – explain purpose of each

Answer 19

amyl nitrite, sodium nitrite and sodium thiosulfate

• nitrites oxidize hemoglobin to methemoglobin –> has higher affinity for cyanide than cytochrome oxidase –> cyanmethemoglobin formed –> cytochrome oxidase restored and ETC can continue its work using O2 as final oxygen acceptor
• thiosulfate promotes conversion of cyanide to thiocyanate which is easily excreted
• methylene blue coverts methemoglobin back to hemoglobin

Question 20

what is in the cyanokit

Answer 20

hydroxocobalamin reacts with cyanide to form cyanocobalamin which is easily excreted in urine

Question 21

enzymes that lead inhibit

Answer 21

ALA dehydratase
ferrochetalase

all leads to reduced heme hence reduce hemoglobin hence anemia

Question 22

treatment of lead poisoning

Answer 22

Cerebral edema - mannitol and dexamethasone

chelation therapy: SEUD
Succimer
Edetate calcium disodium
Unithiol
Dimercaprol

Question 23

mechanism of toxicity of arsenic

Answer 23

• uncoupler of mitochondrial oxidative phosphorylation

- inhibits pyruvate dehydrogenase

Question 24

clinical manifestation of acute arsenic poisoning and treatment

Answer 24

-rice water stool, capillary damage, dehydration and shock

• IV fluids and electrolytes
• first line: Dimercaprol
• Unithiol
• Succimer

Question 25

treatment of mercury poisoning

Answer 25

Succimer
Unithiol
Dimercarprol

(same as lead and arsenic)

Question 26

symptoms and treatment of iron toxicity

Answer 26

GI bleeding

Deferoxamine