Toxicology and Posioning

Question 1

4 ways to prevent absorption

Answer 1

emesis, gastric lavage, chemical absorption, osmotic cathartics

Question 2

2 drugs for inducing emesis

Answer 2

Ipecac and apomorphine

Question 3

when does ipecac make you vom,can you repeat, how does it work, what concern do you have with other overdose problems

Answer 3

throwup in 15-30 minutes, can repeat in 20 minutes, works by local irritation and CMS stimulation of CTZ, MUST be given before activated charcoal

Question 4

apomorphine how does it work and major concern

Answer 4

dopamine agonist that produces emesis by stimulating CTZ , causes respiratory depression and is toxic in kids

Question 5

5 contraindications of emetic agent

Answer 5

comatose, ingestion of corrosive poisons, ingestion of CNS stimulant, ingestion of petroleum distillate, or pgenancy category C

Question 6

Pros/Cons of gastric lavage and when do you need to do it

Answer 6

PRO: most rapid and complete method to empty stomach but CON alvage and emesis only empties 30% of oral poisons, do it within 60 minutes

Question 7

Activated charcoal - how does it work, what does it bind, what can it do, how do you administer it and what challenges do you face

Answer 7

binds drug in the gut to limit absorption and can bind through back diffusion of drug with ion trapping in stomach to reduce elimination half life…. also binds ipecac…. give 10:1 ratio of charcoal:toxin and do it every 4 hours.. hard to administer and kids don’t do well with it

Question 8

purpose of osmotic cathartics, 4 indicated uses

Answer 8

decrease time of toxin in the GI tract like a laxative, do it if the drug was ingested >60 minutes ago, if the toxin is enteric coated tablet or if the toxin is a hydrocarbon

Question 9

4 drugs that do osmotic cathartics

Answer 9

sorbitol 70%, magnesium citrate or sulfate, sodium sulfate, or polyethylene glycol

Question 10

what do you give with sorbitol 70%

Answer 10

charcoal

Question 11

whats recommended for osmotic cathartics

Answer 11

sorbitol 70%

Question 12

magnisum citrate or sulfate should be avoided when

Answer 12

in renal disease or with nephrotoxic agents

Question 13

sodium sulfate gets avoided when

Answer 13

CHF or HTN

Question 14

when do you use PEG for osmotic cathartics

Answer 14

poisonings with sustained release drugs, metal ions, or drug packets

Question 15

differences between hemodialysis vs hemoperfusion

Answer 15

hemodialysis is good for a drug with a small Vd and hemoperfusion is good for drugs with a high MW with a poor water solubility

Question 16

2 means of enhancing renal excretion

Answer 16

1. forced diuresis (protects kidney) 2. block reabsorption from kidney by altering urinary pH

Question 17

2 ways that chelation works

Answer 17

enhances elimination and inactivates toxin

Question 18

in 70-80% of the time with acetametophin metabolism, what phase metabolizes it and what do adults and kids do differently

Answer 18

phase 2 conjugation adults- glucuronic acid, kids- sulfate

Question 19

5-10% of the time with acetametophin (or in overdoses), how does it get metabolized

Answer 19

phase 1 cytochrome p450 oxidation with CYP2E1–> NAPQI or Ac* that then bind proteins or get detoxed by GSH-Transferase and are excreted as mercaptourate

Question 20

2 predisposing factors to hepatic injury from acetametophin injury

Answer 20

increase in CYP2E1 and decrease in hepatic glutathionine (both are also symptoms of alcohol overdose)

Question 21

4 stages of acetametophin toxicity

Answer 21

1 (0-24 hours), 2 (24-48 hours) 3(72-96 hours) 4 (7-8 days)

Question 22

stage 1 of acetametophin toxicity symptoms

Answer 22

not reflective of severity, expect nausea vomitting and abdominal pain

Question 23

stage 2 of acetametophin toxicity is important why and what do you see

Answer 23

see liver damage, increase in plasma aminotransferases and increase in prothrombin time

Question 24

stage 3 of acetametophin toxicity is important why

Answer 24

peak liver toxicity

Question 25

stage 4 of acetometophin toxicity - what happens

Answer 25

if you had gotten good treatment in quickly, recovery. 10% have severe liver damage and 10-20% end up dying

Question 26

2 treatments of acetametophin toxicity and timeframe

Answer 26

1. activated charcoal and gastric lavage in 4 hours and 2. 12-36 hours use N-acetylcysteine

Question 27

loading dose, maintenance dose, and method for using Nacetylcysteine

Answer 27

LD= 140 mg/kg+ 70 mg/kg an hour for 17 doses, give via IV

Question 28

methanol and ethylene glycol pathway of metabolism and rate limiting enzyme

Answer 28

first organic acids (nontoxic) and then gets metabolized to formic acid and oxalic acid, alcohol dehydrogenase is the rate limiting enzyme

Question 29

formic acid is toxic to what and oxalic acid is toxic to what

Answer 29

FA= retinas–> blindness, OA–> acute renal failure

Question 30

what does fomepizole do

Answer 30

inhibits alcohol dehydrogenase so good inhibitor of methanol and ethylene glycol overdose

Question 31

symptoms of methanol and ethylene glycol toxicity

Answer 31

severe metabolic acidosis in 4-12 hours, methanol–> visual disturbances “snowstorm” and ethylene glycol–> deposits calcium oxalate crystals that cause acute renal failure

Question 32

2 ways to inhibit alcohol dehydrogenase

Answer 32

1) infuse EtOH to keep blood alcohol at 0.1% as a competitive inhibitor to saturate the enzyme or 2) fomepizole (better because it doesn’t cause CNS depression)

Question 33

besides alcohol dehydrogenase inhbition, how else can you treat methanol and ethylene glycol toxicity

Answer 33

hemodialysis to correct for metabolic acidosis