PED1003/L07 Pharmacokinetics in Practice Flashcards
Why are kinetic parameters calculated?
To ensure that the dosage regimen results in the correct plasma concentration in all patients irrespective of disease state, capacity to eliminate, route of administration, age and other drug therapy
Describe the one compartment model.
(Over)simplified model that a human consists of a single well-stirred compartment
Drug is absorbed, immediately distributed and subsequently eliminated
How many half-lives are passed to reach a steady state?
4-5
What does the concentration at Css depend on?
Frequency of administration
What is the purpose of kinetic orders?
It relates the plasma concentration of a drug and its rate of elimination from the body
Give 3 properties of first order elimination.
Decrease in drug is dependent on plasma concentration
Concentration of drug is rate limiting factor
Exponential decrease
Describe the two compartment model.
Drugs will only enter body tissues (peripheral compartment) via the plasma (central compartment)
Predicts a fast and slow phase of distribution between compartments
Give 3 properties of zero order elimination.
Decrease in drug is independent of plasma concentration
Rate is constant due to limiting factor
Straight line
Describe saturation kinetics with alcohol. (2)
Concentration falls linearly rather than exponentially
Rate of fall does not vary with dose
What is the half-life of clotrimazole?
20 mins
