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Toxicology > Basic Principles of Toxicology (2) > Flashcards

Basic Principles of Toxicology (2) Flashcards

1
Q

T/F: Everything is toxic at the right dose

A

TRUE

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2
Q

Is a lethal dose (LD50) of ethyl alcohol (10,000 mg/kg) more lethal than a dose of nicotine lethal dose of 1 mg/kg?

A

nicotine: takes way less to reach the lethal dose

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3
Q

What is NOAEL?

A

no observed adverse effect level

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4
Q

What is LD50 or LC50?

A

lethal dose/concentration that kills 50% of a test population

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5
Q

What is MTD?

A

minimum toxic dose

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6
Q

What is MLD/MLC?

A

minimum lethal dose/concentration

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7
Q

Of NOAEL, LD50, MTD, and MLD/MLC is likely of most clinical use?

A

MTD - at what point would we need to treat therapeutically?

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8
Q

T/F: Cats are just small dogs regarding toxicity

A

FALSE

there are species specific values for toxicity

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9
Q

Exposure [does / does not] equal intoxication

A

does not

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10
Q

Why doesn’t exposure equal toxication?

A

the toxin must be absorbed and reach its site of action at a HIGH enough concentration and for a sufficient period of time to cause a toxic effect

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11
Q

What is the first thing we need to worry about with exposure to a toxin?

A

absorption

need to try and get it before it penetrates

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12
Q

What are the basic events with toxicokinetics?

A

ADME

Absorption
Distribution
Metabolism
Excretion

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13
Q

What is the most critical event of toxicokinetics?

A

metabolism - can convert a dangerous toxin to safer

OR

moderately dangerous to worse (like aspirin)

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14
Q

Regarding absorption and toxicokinetics, how can a toxin get into the body?

A

orally/ingestion
dermal exposure
injection
IV, SQ, IM, IP
inhalation

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15
Q

Can we minimize absorption? If so, how?

A

yes - decontaminate like throwing up or cleaning skin

you’re SOL if it’s been injected though

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16
Q

Regarding toxicokinetics and distribution, where does it go?

A
  • fat solubility vs water solubility
  • protein binding
  • pH of tissues and compartments - blood and rumen
    etc
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17
Q

Regarding toxicokinetics and distribution, what happens when it gets there?

A

biotransformation (metabolites more readily excreted) - often converted to a more water-soluble product

BIG SPECIES DIFFERENCE

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18
Q

Regarding toxicokinetics and excretion, how does it get out of the body?

A
  1. urinary
  2. biliary/fecal
  3. also milk, sweat, saliva
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19
Q

What is this?

A

a “typical” dose-response curve

  • increased levels of toxicity
  • dose makes the poison
20
Q

What is this kind of curve?

A

a bi-phasic curve around zone of homeostasis

deficiency vs. toxicity

21
Q

Describe this dose-response curve

A

similar to nutrients except no deficiency part (no negative)

more typical of pharmaceutical medicine

22
Q

What graph is this of?

A

essential nutrients - compared to therapeutic medications (hormesis) where there is no deficiency

23
Q

What is the therapeutic index?

A

the ratio of the dose of the drug that produces an unwanted (toxic) effect to that producing a wanted (therapeutic) effect

24
Q

A [small/large] therapeutic index is better. Why?

A

large - the bigger the space, the better

If you have a LD of 5 and an ED (effective dose) of 1, the TI would be 5

But if you have a LD of 2 and an ED of 1, the TI would be 1 which is very close to the lethal dose

25
Q

What factors influence toxicity?

A
  • characteristics of the animal/animals exposure
  • route of exposure
  • frequency of exposure
  • characteristics of the toxicant
  • environmental conditions
26
Q

Regarding characteristics of the animal, how does that affect toxicity?

A
  • species
  • genetic differences (polymorphisms)
  • age
  • etc
27
Q

What characteristics of the toxins influence toxicity?

A
  • formulation, vehicle
  • valence state of metals
  • ionization
  • decomposition
  • impurities
  • strain/subspecies
28
Q

Regarding frequency of exposure, how does that affect toxicity?

A
  • one time exposure
  • repeated exposure
  • cumulative effects
29
Q

Regarding environmental conditions, how does that affect toxicity?

A
  • drought
  • time of year
  • growth stage
  • temperature
  • photo period
  • winds

not all plants are toxic all the time

30
Q

T/F: Our first question should be “Is this toxic?”

A

FALSE - we should ask

  • At what dosage
  • In what species?
  • Under what conditions?
31
Q

Many toxicants exhibit a ____ dose-response relationship

a. “typical”
b. essential nutrients
c. hormesis

A

“typical” dose-response relationship

32
Q

What is the metric conversion for 1 ounce and 1 pound?

A

1 ounce = 28g

1 pound = 0.454 kg

33
Q

What is the metric conversion for 2.2 pounds and 1 ton (short)?

A

2.2 pounds = 1 kg

1 ton (short) = 0.9 metric tons

34
Q

What is the metric conversion for 1 fl. ounce, 1 teaspoon, and 1 tablespoon?

A

1 fl. ounce = 30 mL

1 teaspoon = 5 mL

1 tablespoon = 15 mL

35
Q

What is the metric conversion for 1 cup, 1 quart, and 1 gallon?

A

1 cup = 0.24 L

1 quart = 0.95 L

1 gallon = 3.8L

36
Q

One metric ton is how many kg and lbs?

A

1000 kg

2200 pounds

37
Q

When are dose calculations used?

A

involving a KNOWN exposure to a specific toxicant

38
Q

Why calculate dose of exposure?

A

to determine if the dose is high enough to pose a risk of intoxication or death

39
Q

Why not just treat any exposure?

A

risks (and expense) of treatment may outweigh risk of intoxication

aggressiveness of treatment will be determined by severity of intoxication

40
Q

What is the #1 question to ask the client if they suspect their animal ate something?

A

“How are they doing now”?

41
Q

What is cholecalciferol? What does it do?

A

vitamin D3

usually balances Ca2+ and PO4-

42
Q

Calculate the dose received (in mg/kg) of a 23 lb dog named Bob who ate 5 blocks of rat bait (17g per block) with a cholecalciferol concentration of 0.065%

A

0.055 g cholecalciferol

5.24 mg/kg dose

43
Q

The minimum lethal dose (MLD) for that dog was 3.3 mg/kg and minimum toxic dose (MTD) was 0.2 mg/kg. Is Bob safe? Why or why not?

A

NO - his dose was 5.24 mg/kg which is way over even the lethal dose

44
Q

Calculate the dose received (in mg/kg) of a 85 lb dog named Pippa who ate 3 blocks of rat bait (12g per block) with a cholecalciferol concentration of 0.065%

A

cholecalciferol: 0.023 g

dose: 0.600 mg/kg

45
Q

The minimum lethal dose (MLD) for that dog was 4.7 mg/kg and minimum toxic dose (MTD) was 0.58 mg/kg. Is Pippa safe? Why or why not?

A

no - she has ingested the MTD, but it is not enough to kill her

Toxicology (20 decks)

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