Module 9 Flashcards
Dose-response information is determined/established in which phase of clinical trials?
Phase 2
What is the ED50 (in reference to a frequency distribution curve)?
The ED50 is the dose required to produce a response in 50% of the population.
What is often used as the initial dose for therapy?
the ED50
The initial dose of a drug is a starting point, however many patients will require dose adjustments in order to what?
Optimize efficacy and minimize adverse events
When is it OK to use the ED50 as the starting dose?
When the drug has a wide therapeutic range
How do we dose drugs that have a narrow therapeutic range?
Drugs with a narrow therapeutic range should have their dose titrated (start low and increase slowly until the desired response is achieved)
It is important to adjust dosing based on what?
The patient’s response rather than simply using a dosing reference.
What is the average toxic dose (TD50)?
The dose in which 50% of animals experience drug toxicity
What is the average lethal dose (LD50)?
the dose in which 50% of animals die
How are the TD50 and LD50 typically expressed?
in mg drug/kg body weight
What is the therapeutic index?
It is an indicator of a drug’s safety.
The therapeutic index is calculated by determining the ratio of the TD50 or LD50 to the ED50.
TI = TD50/ED50 or TI = LD50/ED50 Drugs with a high therapeutic index are considered safe whereas those with a low therapeutic index are considered unsafe.
What are some factors affecting interpatient variation in response?
- Body Weight and Composition
- Genetics
- Sex
- Race
- Kidney Disease
- Liver Disease
- Environment
The response to medications is largely determined by what?
The concentration of the drug in the body (with higher concentrations giving a greater response)
