Test 4: 45 principles part 1 Flashcards
most common toxins of tremorgenic mycotoxins
penitrem A (moldy walnuts)
roquefortine C (soft cheeses)
at least 20 mycotoxins have been identified as tremorgens- most commonly associated with penicillium species
tremorgenic mycotoxins cause intoxication in what type of animals
a bunch
dogs, cattle, sheep, rabbits, rodents, poultry
molds that lead to tremors
how does tremorgenic mycotoxins work
several proposed theories
May vary both between specific toxins and individual susceptible species
- Penitrem-A inhibits the inhibitory neurotransmitter glycine in mice
- Another tremorgen, verruculogen, reduces concentrations of GABA in the brain
treatment for tremorgenic mycotoxins
Diazepam and methocarbamol
if not responding to diazepam: barbiturates (pentobarbital)
how to decontaminate tremorgenic mycotoxin intoxication
sedate and gastric lavage if pt has not vomited
activated charcoal and a cathartic
sedation will decrease risk of tremor and ET tube will prevent aspiration
general treatment for tremorogenic mycotoxin poisoning
- Thermoregulation
- Treat for shock
- Intravenous fluid support
- Prognosis good with early and aggressive treatment
- No long-term sequelae expected
1947 Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA): Non-food, non-drug substances had to be shown to be —
safe and efficacious
alternate term for poison, any agent capable of producing a deleterious response in a biological system
toxicants
poison that originates from biological processes
toxin
Toxicity vs toxicosis
Toxicity = quantity or amount that causes a toxic effect
Toxicosis = disease state that results from exposure to a poison
threshold dose vs LD50 vs median lethal dose
Threshold dose = highest dose of toxicant at which toxic effects are not observed
Lethal dose 50% or LD50 = the dose at which 50% of the animals die
Median lethal dose (MLD) = used interchangeably with LD50
NOEL and NOAEL
no observed effect
level
no observed adverse effect level
LOEL and LOAEL
LOEL: lowest observed effect level
LOAEL: lowest observed adverse effect level
the — the therapeutic index, the safer the chemical
larger
TI= LD50/ED50
if large number, there is a wide dose that can be given before toxic effects
the smaller the standard safety margin the — the chemical
more dangerous
SSM= LD1/ED99
standard safety margin (SSM)= margin of safety (MoS)
chronic toxic effects may occur if chemicals —, toxic effects products are — or there is — between exposures
accumulate
irreversible
insufficient recovery time
additive effect vs synergistic effect
additive: 2+3=5
synergistic: 2+3=20 (greater than the sum of the individual, occur if one chemical affects the solubility, binding, metabolism, or excretion of
the other
potentiation
one otherwise non-toxic or only mildly-toxic chemical enhances the toxicity of another chemical
0 + 2 = 20
- Isopropanol is not hepatotoxic, however enhances the hepatotoxicity of carbon tetrachloride
antagonism can work in three ways
Physiologic – epinephrine antagonizes hypotensive effects of phenobarbital
Chemical – calcium EDTA complexes with lead
Metabolic – ethyl alcohol competes with ethylene glycol (EG), preventing EG’s activation to toxic metabolites
for dose response what three assumptions are made
- The chemical interacts with a molecule or receptor site to produce a response
- The production of the response, or degree of response, is correlated to concentration of the chemical at that receptor site
- The concentration of the chemical at the receptor site is related to the dose of chemical received
hormesis
Some xenobiotics impart beneficial or stimulatory effects at low doses but have adverse effects at higher doses
selenium, Vit A
cadmium will cause – is ingested, inhaled or touched
Oral exposure → renal lesions
Inhalation exposure → lungs 1st +/- kidneys
Dermal exposure → produces little if any toxicity
Felines possess limited —capabilities, so must rely on the less- efficient sulfate & cysteine conjugation pathways compared to dogs
glucuronidation
why are young animals usually more susceptible to toxins
- GI mucosa and blood-brain barrier are less developed
- Drug-metabolizing enzymes are generally less active
- Higher proportions of body water and lower proportions of body fat influence distribution and storage of drugs and chemicals
