Toxicology Flashcards
TLV-TWA v TLV-C v PEL
Threshold limit values: time weighted averages v ceiling
Permissible exposure limits (fed regulations)
Margin of Safety
LD1/ED99
Bioaccumulations v biomagnification
compound persistent in body v accum with each food chain link
Pharmacokinetics v pharmacodynamics
kinetics: how body impacts drug
dynamics: how drug impacts body
Pharmacokinetic: change absorption
impact tract function (motility and/or absooprtion) alter content (Ca2+ or pH)
Pharmacokinetic: change distribution
- Plasma protein binding (albumin) –> more free drug –> more toxicity
- tissue binding displacement
Example of plasma protein binding displacement
salicylates (aspirin) displaces warfarin and phenytoin (anti-epileptic) from albumin
(increases toxicity of warfarin and phenytoin)
Example of tissue binding displacement
quinidine displaces digoxin from tissue (if taken within 24 hours)
Pharmacokinetics: change metabolism
Induce or inhibit metabolism
Example of metabolism inducer
phenobarbital (slow acting; requires protein producction)
Example of metabolism inhibitor
ketoconazole (CYP3A4)
cimetidine (H2 blocker)
Pharmacokinetics: change excretion
weak acid transport in proximal tubule (change this mechanism)
pH of urine
Drug that alters weak acid transport in proximal tubule?
probenicide blocks –> increase half life of drugs that use this mechanisms (ex penicillin)
Drugs that alter pH of urine
sodium bicarb (increases elim of weak acids)
ammonia chloride, ascorbic acid (""bases)Naloxone pharmacodynamics
true antagonist of opiates
Tamoxifen pharmacodynamics
partial antagonist to estrogen receptor
Gingko biloba shouldn’t be taken with what? why?
NSAIDs
inhibit platelet aggregation –> increased bleeding risk
Grapefruit juice shouldnt be taken with what? why?
calcium channel blockers (CCB) (ex. verapamil)
grapefruit juice inhibits CYP3A4 –> more free CCB –> more toxicity (hypotension and myocardial depression)
What should not be taken with ketoconazole? why?
CYP3A4 drugs
ketoconazole (like grapefruit juice) inhibits CYP3A4 –> more toxicity
What should not be taken with warfarin?
phenobarbital. phenobarbital induces drug metab (makes warfarin less potent)
What should not be taken with acetaminophen?
ethanol
induces the “overdose pathway” via CYP2E1 metabolism –> liver enzymes; necrosis
HOw do you treat acetaminophen overdose?
N-acetylcysteine withhin 15-24 hours; will bind metabolite
Basics of poison management
airway- no obstruct
breathing- eval, blood gas
circulation- pulse, pressure
dextrose-thiamine- if altered CNS, can prevent neuron death
How to treat cyanide poisoning?
stabilize
amyl nitrite/sodium nitrite
sodium thiosulfate (kit)
Iron poisoning clinical signs? treat?
vomit, diarrhea; remission; shock, seizure, liver failure
treat: deferoxamine (chelator); monitor urine color and serum Fe levels
Lead poisoning signs? treat?
nausea, constipation/diarrhea, ab pain; urinary exrcretion; MR/personality changes; blue lead line on gums, peripheral neuropathy (wrist/foot drop)
Treat: dimercaprol and calcium EDTA
Ethylene glycol poisoning signs and treat?
antifreeze
increased osmolar gap–> anion gap acidosis (lab)
Treat: ethanol or fomepizole (expensive)
Ricin poisoning mechanism
castor bean plant
binds 60s ribosome–> protein synthesis disruption
Amanita mushroom mechanism? treat?
cyclopeptide inhib RNA pol II –> decr protein synthesis –> cell necrosis
possible liver transplant?
