Chapter 3 lecture 3-4 Flashcards
(45 cards)
What is the difference between toxicokinetics and toxicodynamics?
- Toxicokinetics: What we do to the chemical
- Toxicodynamics: what the chemical does to us
The _ and _ of exposure is an important determinant of the ultimate dose
The route and duration of exposure is an important determinant of the ultimate dose
What are the 4 major routes of exposure/administration?
- GI tract
- Lungs
- Skin
- Other paprental routes
Compare the speed and degree of effect between
* Intravenous Injection
* Oral/dermal exposure
- 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
What are the 6 frequencies of exposure to toxic substances?
different from the toxicity in lecture 1
- Acute exposure
- Sub-acute
- Sub-chronic
- Chronic
- Life-time
- Exposures over generations
What is acute exposure?
- a single exposure to a chemical for less than 24 hours
- Repeated dose within 24 hrs also count
What is sub-acute exposure?
- Must be 13-40 doses
- Over a period of days, < 30 days
What is Sub-chronic exposure?
The repeated doses spreading 1-3 months
What is chronic exposure?
- The exposure > 3 months
- < lifetime, but experimental settings usually close to the expected lifetime
What is life-long exposure?
Repeated dose/ continuous throughout the whole lifespan.
What is exposures over generations?
- Impaired reproductive cabibility/
- genetically mediated damage
- the exposure can be maintained over several generations
What is the definition of dose?
The amount of a substance
administered at one time.
What are the other parameters that are needed togeteher with dose?
- no. of dose
- frequency
- Total time period
Why do we fractionate a total dose?
- To decrease the probability that the total dose will cause toxicity
- Body can repair the effect of each subtoxic dose in sufficient time
Why do we fractionate a total dose?
- To decrease the probability that the total dose will cause toxicity
- Body can repair the effect of each subtoxic dose in sufficient time
The clinical and toxic effects of a dose must be
related to _ and _.
The clinical and toxic effects of a dose must be
related to age and body size.
Why children and adult cannot recieve the same dose?
- Due to different metabolic rate
- Kids dun have much ability to detoxify the drug
A common dose measurement is mg/kg
Describe dose response
It correlates exposure with the spectrum of induced effects
By what ways can the dose-response relationship be determined?
Based on experimental animals, human clinical
NOT CELL STUDY CUZ CAN’T SHOW WHATS HAPPENING TO WHOLE BODY
What can dose-response relationship tell?
- establishes causality that the chemical has in fact induced the observed effects
- establishes the lowest dose where an induced effect occurs -the threshold effect
- determines the rate at which induced effect builds up - the slope for the dose response.
How to explain the variability within population?
Bell-shaped normal distribution curve.
What is the shape for the dose-response curve?
Sigmoidal shape
What is threshold value?
The point at which toxicity first appears
What does the threshold of toxic effect mean?
The ability to detoxify or repair injury has been exceeded.
eg: The development of cirrhosis needs 50% of liver replaced by firbous tissue.
