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BIOL3207 Toxicology > Chapter 3 lecture 3-4 > Flashcards

Chapter 3 lecture 3-4 Flashcards

1
Q

What is the difference between toxicokinetics and toxicodynamics?

A
  • Toxicokinetics: What we do to the chemical
  • Toxicodynamics: what the chemical does to us
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2
Q

The _ and _ of exposure is an important determinant of the ultimate dose

A

The route and duration of exposure is an important determinant of the ultimate dose

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3
Q

What are the 4 major routes of exposure/administration?

A
  1. GI tract
  2. Lungs
  3. Skin
  4. Other paprental routes
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4
Q

Compare the speed and degree of effect between
* Intravenous Injection
* Oral/dermal exposure

A
  • Intravenous Injection: exact amount will reach target organ, quickest, cuz blood directly take chemical to organ
  • Oral/dermal: there must be metabolism lost, lose effect
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5
Q

What are the 6 frequencies of exposure to toxic substances?

different from the toxicity in lecture 1

A
  1. Acute exposure
  2. Sub-acute
  3. Sub-chronic
  4. Chronic
  5. Life-time
  6. Exposures over generations
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6
Q

What is acute exposure?

A
  • a single exposure to a chemical for less than 24 hours
  • Repeated dose within 24 hrs also count
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7
Q

What is sub-acute exposure?

A
  • Must be 13-40 doses
  • Over a period of days, < 30 days
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8
Q

What is Sub-chronic exposure?

A

The repeated doses spreading 1-3 months

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9
Q

What is chronic exposure?

A
  • The exposure > 3 months
  • < lifetime, but experimental settings usually close to the expected lifetime
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10
Q

What is life-long exposure?

A

Repeated dose/ continuous throughout the whole lifespan.

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11
Q

What is exposures over generations?

A
  • Impaired reproductive cabibility/
  • genetically mediated damage
  • the exposure can be maintained over several generations
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12
Q

What is the definition of dose?

A

The amount of a substance
administered at one time.

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13
Q

What are the other parameters that are needed togeteher with dose?

A
  1. no. of dose
  2. frequency
  3. Total time period
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14
Q

Why do we fractionate a total dose?

A
  • To decrease the probability that the total dose will cause toxicity
  • Body can repair the effect of each subtoxic dose in sufficient time
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14
Q

Why do we fractionate a total dose?

A
  • To decrease the probability that the total dose will cause toxicity
  • Body can repair the effect of each subtoxic dose in sufficient time
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15
Q

The clinical and toxic effects of a dose must be
related to _ and _.

A

The clinical and toxic effects of a dose must be
related to age and body size.

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16
Q

Why children and adult cannot recieve the same dose?

A
  • Due to different metabolic rate
  • Kids dun have much ability to detoxify the drug

A common dose measurement is mg/kg

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17
Q

Describe dose response

A

It correlates exposure with the spectrum of induced effects

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18
Q

By what ways can the dose-response relationship be determined?

A

Based on experimental animals, human clinical

NOT CELL STUDY CUZ CAN’T SHOW WHATS HAPPENING TO WHOLE BODY

19
Q

What can dose-response relationship tell?

A
  1. establishes causality that the chemical has in fact induced the observed effects
  2. establishes the lowest dose where an induced effect occurs -the threshold effect
  3. determines the rate at which induced effect builds up - the slope for the dose response.
20
Q

How to explain the variability within population?

A

Bell-shaped normal distribution curve.

21
Q

What is the shape for the dose-response curve?

A

Sigmoidal shape

22
Q

What is threshold value?

A

The point at which toxicity first appears

23
Q

What does the threshold of toxic effect mean?

A

The ability to detoxify or repair injury has been exceeded.
eg: The development of cirrhosis needs 50% of liver replaced by firbous tissue.

24
Q

To estimate acute toxicity, LD50 can be used. What is the meaning of this?

A

The dose at which 50% of the individuals will be expected to die

25
Q

What is the difference between LD0 and threshold?

A

LD0: The dose at which no individuals are expected to die
Threshold: The dose at which toxicity has begun/first appears

26
Q

What is Effective dose?

A

EDs are used to indicate the effectiveness
of a substance.

27
Q

What is toxic dose?

A

TDs are utilized to indicate doses that cause adverse toxic effects.

28
Q

ED is only used to describe toxic effect, T/F?

A

F

29
Q

What is Therapeutic Index (TI)?

A

compare the
therapeutically toxic dose to the effective dose .
TD50/ED50

A statement of relative safety of a drug

30
Q

TI can be used for drugs/ toxic substance?

A

Drugs, therapeutic

31
Q

What does small/large TI indicate?

A
  • A large TI indicates a safer drug
  • A smaller TI indicates a more dangerous drug
32
Q

Why TI can be misleading?

A
  1. It conly consider the slope for the response curves
  2. It does not take concentraton into consideration
33
Q

What is MOS-Margin of Safety?

A

MOS = LD01/ED99

34
Q

What does the extent of MOS value indicate?

A

Pharmist mus be considerate to prescribe drugs with MOS <1

35
Q

NOAEL, LOAEL and Threshold are actual data point. T/F

A

True

36
Q

What is NOAEL?

A
  • No observed adverse effect level
  • Highest data point at which there wasn‘t an observed adverse effect
37
Q

What is LOAEL?

A
  • Low observed adverse effect level
  • The lowest datapoint at which there was and observable adverse effect
38
Q

What substance gives a u shape dose response curve?

Inverted dose relationship

A

Vitamins

39
Q

What substance gives a u shape dose response curve?

Inverted dose relationship

A

Vitamins

40
Q

What is potentiation?

A

where one chemical/drug enhances the
effect of another
Substance A is not toxic by itself, but can enhance toxic effect of substance B

41
Q

What is antigonism

A

The opposite effect where one compound
blocks or reduces the effect of the other

antidotes

42
Q

Recall the example of naloxone and heroin

A

The receptor antagonist naloxone binds competitively to the receptor for opiate narcotics, thus reducing the toxic effects of heroin.

43
Q

Describe what additivity is.

A

the combined effect of two or more chemicals is equal to the sum of the individual effects.

44
Q

Describe what synergism is.

A

A toxicity that is greater when two compounds are
given simultaneously or sequentially than would be
expected from a consideration of the toxicities of
the compounds given alone.

BIOL3207 Toxicology (7 decks)

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