Chapter 3: Dose Responses Pt 2 Flashcards
What is ED50?
where the drug is doing what we want it to do in 50% of the population
What is TD50?
toxic dose where adverse effects start happening in 50% of the population
What is the TI? How is it calculated?
The therapeutic index (TI) is the ratio of TD50 and ED50. high values mean that the drug is relatively safe. low values usually lead to the rejection of the drug from further clinical testing.
TiI = TD50/ED50
What does potency mean?
the amount required to produce an effect of given intensity.
What does efficacy mean?
refers to the maximum response achievable.
What is NOEC?
No observable effect concentration (if we get down to this [ ] we see nothing happen basically).
What is LOEC?
Lowest observable effect concentration. the barest minimum concentration required to get a response.
What does hormesis mean?
Dose-response curves where compounds are beneficial/stimulatory at low doses, but toxic at high doses.
What is a biomarker? What are some examples of biomarkers?
A cellular or biochemical response to a toxicant that is measurable in a biological system or sample.
enzyme activity, changes in cellular receptor amount and activity, changes in hormone levels, increased/decreased expression of genes that respond to toxicants, changes in the cell structure to dectect cellular damage using histology
What do chronic bioassay’s look at? What is an example of what can’t be identified in a subchronic study?
they look at longer-term endpoints like cancer developments (months to years). Cancer can take a long time to develop and likely will not be identified in a sub chronic study.
What is an example of regulatory breakdown?
Rofecoxib (trade name is Vioxx) is a non-steroidal anti-inflammatory drug that was produced by Merck Pharmaceuticals. Merck pulled the drug from market, because prolonged high-dose use could lead to heart failure in some people.
