Pharmacokinetics 1 Flashcards
Why is there a bad relationship between dosage of a drug and its effect?
The pharmacokinetic ADME processes interfere with this relationship
How can the variability between dose and effect be overcome?
The concentration of the drug can be measured at the site of action, however this is often impractical so it is better to measure the drug plasma concentration, as at steady state there is much less variation between concentration and effect
What is the difference between pharmacokinetics and pharmacodynamics?
Pharmacokinetics looks at the relationship between drug dose and concentration time profile in the body while pharmacodynamics looks at the relationship between drug concentration and effect
What are the three key concentrations that must be taken into account when determining the appropriate dose of a drug?
The minimum effective concentration, maximum effective concentration and toxic concentration
What is the therapeutic range of a drug?
The concentration range which has the highest probability of giving the desired response with the minimum side effects
What is distribution?
The reversible movement of drug between body compartments
How can volume of distribution be calculated?
A known dose can be given to a patient, the concentration of the drug in the blood can then be measured
Volume= Dose/Conc
What is the apparent volume of distribution?
The volume of the drug that must be dissolved in so it can give the concentration equivalent to that found in plasma
Not a physiological volume, but provides insight into distribution of plasma and tissue uptake
What is a loading dose and how is it calculated?
It is a dose required to rapidly reach a target concentration, and is calculated by multiplying the target concentration by the volume of distribution
Does volume of distribution influence the steady state concentration?
No, steady state is determined by clearance of the drug and its rate of input
