2- Understanding the importance of pharmacokinetics to the patient Flashcards
Define bioavailability
A measure of the extent of drug absorption from administration to measurement site
(Fraction of administered dose that reaches the plasma)
What are the 4 key steps of a drugs life?
Absorbed to the circulatory system
Distributed about body
Metabolised
Excreted
What is Cmax?
Maximum plasma drug concentration after
administration of drug
What is Tmax?
Time at which Cmax occurs (maximum plasma drug conc)
What is the rate of drug absorption dependent on?
Route of administration
Define drug elimination rate
Amount of parent drug eliminated from the body per unit time
What needs to happen to a drug before it can be eliminated?
Metabolised
In general, drugs are lipid soluble so conversion into a water-soluble drug
List the 3 main routes of drug excretion
Kidney (urine), hepatobiliary system, Lungs
T/F Drugs bound to plasma proteins are excreted via the urine
False = can’t be filtered into the lumen
Reabsorption of drugs out of the kidney tubules depends on what?
Lipophilicity of drugs = affinity for lipids - so can cross the membrane
(Drugs that are not will remain in the tubule and be excreted)
Define volume of distrubition
Volume in which a drug appears to be distributed with a concentration equal to that of plasma
Define half-life
The time required for the amount of drug in the body to decrease by 50%.
Define clearance
The volume of blood/plasma cleared of parent drug per unit time
Sum of all organ clearances
Why do some drugs stay in the blood and not get distributed to tissues?
Tightly bound to plasma proteins
