69/70: Toxicology

Question 1

primary determinant of toxicity **

Answer 1

dose

time is the other determinant (duration of time that chemicals present in body)

Q1: What was the does? How much did the person ingest?
Q2: How long ago?

Question 2

dose at which 50% of tested animals die

Answer 2

LD50

TD50 = dose at which 50% have toxicity

legally, a poison has an LD 50 less than 50 mg/kg/bw

Question 3

therapeutic index =

Answer 3

LD50/ ED50

the LARGER the number, the SAFER the drug

Question 4

how is the ALD average lethal dose calculated?

Answer 4

estimated from accidental deaths in humans

Question 5

give for narcotic overdose

Answer 5

naloxone

Question 6

toxidromes =

Answer 6

known toxicology standards

Question 7

emesis inducers

Answer 7

to remove unabsorbed toxicants from GI tract

• mechanical
• Apomorphine
• syrup of Ipecac

could also use gastric lavage (stomach pump)

Question 8

contraindications to the use of emesis inducers

Answer 8

• petroleum hydrocarbon solvent (chemical pneumonitis)
• caustic acid or alkali agent ( rupture)
• seizing or comatose pt

Question 9

why would you use activated charcoal ?

Answer 9

very lg SA allows binding of organic toxicants which prevents absorption

induces emesis

administered orally in water

Question 10

pralidoxime/ 2PAM is an antidote for?

Answer 10

treat poisoning by organophosphates

it is a nucleophilic reagent that covalently binds to organophosphates and permits rapid exretion

usually administered with ATROPIEN to block muscarinic effects of parasymptathetic nervous system

Question 11

what do you administer as antidote for cyanide poisoning?

Answer 11

amyl nitrite (inhaled) followed by sodium nitrite (IV) then sodium thiosulfate (IV) with O2 and whole blood

cyanide - death in 1-15 min because disrupts ETC (block cytochrome c oxidase) - no more ATP production

Question 12

how do you treat botulinum toxin?

Answer 12

with antibodies formed in horse directed at botulinum toxin

single 10 mL vial/pt

botulinum toxin is most potent poison known, rapidly absorbed and prevents ACh release from n. terminals. most commonly affects respiratory depression.

Question 13

how do you treat heavy metal intoxication?

Answer 13

chelators - bind with metal making them inert and increasing renal excretion

ex: BAL

Question 14

Use: DMSA, succimer

Answer 14

tx of arsenic, mercury and LEAD poisioning

adults and kids over 12: 10mg/kg/PO, q8h for 5 d

children under 11: 10mg/kg/PO q8h for 5 d THEN q12h for 14d (19 d therapy)

adverse rxns: unpleasant odor to urine, sweat, feces, loos stools, loss of appetite,

Question 15

ethylene glycol =

Answer 15

antifreeze

Question 16

methanol is converted into formaldehyde and formic acid by …

how do you save?

Answer 16

alcohol dehydrogenase

ethanol admin competitively prevents alcohol dehydrogenase from converting these substances (ethylen glycol/methnaol/isopropyl alcohol) into toxic forms

hemodialysis is given as adjunct

also give FOMEPIZOLE - blocks alcohol dehydrogenase

Question 17

drug of choice for antidotal therapy for ethylene glycol or methanol toxicity

Answer 17

fomepizole

Question 18

treatment for carbon monoxide poisoning (cherry red appearance)

Answer 18

artificial respiration with pure O2 to promote displacement of CO; hyperbaric oxygen chamber if symptomatic

Question 19

warfarin reversal =

Answer 19

injection of vit K or prothrombin complex or FFP infusion to replace coagulation prtns

s/s hemoptysis, excessive bruising, bleeding from nose or gums, or blood inurine or stool

Question 20

MOA naloxone

Answer 20

acts at mu, kappa and delta receptors to competitively block/reverse teh effects of opiates
- 45 min duration of action

use opiod overdose - fast acting

Question 21

MOA naltrexone

Answer 21

• same at naloxone (competitive inhibitor) but longer duration of action (24-72 hrs)

use opiod overdose – follows nalterxone, also withdrawal treatment

Question 22

used to treat methemoglobinemia

Answer 22

methylene blue

cause a direct chemical reduction of methemoglobin back to hemoglobin

Question 23

define toxidromes

Answer 23

common and well-characterized clinical syndromes that provide a symptomatic fingerprint allowing for recognition of patterns of poisoning associated with specific intoxicants

Question 24

mydriasis
HTN
tremor
hyperthermia

Answer 24

sympathomimetic toxidrome

drugs: cocaine, amphetamines, PCP

Question 25

coma
decreased respiration
miosis or mydriasis
hypotension

Answer 25

sedative/hypnotic toxidrome

drugs: alcohol, barbiturates, benzodiazepines

Question 26

coma
depressed respiration
pinpoint pupils
hypothermia
hypotension
histamine release

Answer 26

opioid toxidrome

drugs: heroin, morphine, codeine, propoxyphene, oxycodone, hydrocodone

opiate triad = hypothermia, hypotension and histamine release

Question 27

agitation
mydriasis
fever
dry skin
flushing
urinary retention

Answer 27

anticholinergic toxidrome

hot dry mad red blind

drugs: anticholinergics, antidepressants

Question 28

SLUDE
salivation
lacrimation
urination
defecation

pinpoint pupils

Answer 28

cholinergic toxidrome

drugs: organophosphates (insecticides) , nicotine

Question 29

diaphoresis
tinnitis
agitation
alkalosis early, acidosis late
hyperpyrexia

Answer 29

salicylate toxidrome

drugs: ASA

Question 30

flumazenil

Answer 30

benzo overdose tx

Question 31

n-acetylcysteine

Answer 31

acetaminophen overdose tx

restores glutathione (liver toxicity)