Pharmacokinetics Flashcards
(20 cards)
what is pharmacokinetics?
the study of the basic process that determines the duration and intensity of a drug effect
what the body does to the drug
define absorption
refers to how medicines enter the blood stream (Plasma)
define distribution
the reversible transfer of a drug from the bloodstream to the tissue. The drug moves between different body compartments, drug reaches the site of action (receptors)
define volume of distribution
Vd not a real physiological volume rather a proportionality constant that relates to the amount of drug in the body to its concentration in the blood.
define excertion
how the body removes a medicine
define clearance
CL reflects the elimination of the drug from the body & is related to the plasma concentration and dose rate.
it is a collection of processes by which the body removes the drug from the body
define half life
the time it takes to remove half the current concentration of the drug from the body
what are the four principles of pharmacokinetics ?
- Absorption
- Distribution
- Metabolism
- Elimination
What is ADME?
Absorption, Distribution, Metabolism, elimination
What is the absorption rate dependent on?
Route of Administration
what is absorption influenced by?
Concentration gradient, drug size, lipid solubility/ ph
what is bioavailability?
the fraction of the drug the reaches the systemic system.
what is the formula to work out Volume of distribution?
Vd = dose (amount of drug in body) / plasma conentration
What does the magnitude of Vd indicate?
the Distibution of the drug in the body but not location
What does a small volume of distribution mean?
mainly retained in blood
What does a large volume of distribution mean?
majority of drug moves out of blood into tissues
what are two barriers to drug distribution?
blood brain barrier
Placentea
define metabolism
is the irreversible conversion of one chemical compound into another
what are the two main route of administration?
one) excretion by the kidneys (urine)
two) excretion by faeces
what are the twos of clearance?
metabolism and elimination
