Flashcards in Advanced Pharmacokinetics Deck (18):
In rapid IV administration how does the drug distribute?
In rapid IV administration how does the amount of drug in the body fall?
exponentially with time
In rapid IV administration what is peak concentration related to?
In a short term IV infusion at what rate to drugs infuse?
Is the peak concentration higher in a rapid IV administration or a short term IV infusion?
rapid IV administration - because in short term IV infusion there will be drug elimination while there is absorption
How is the drug eliminated in a short term IV infusion after the infusion is over?
first order - exponentially with time
Which type of drugs is a short term IV infusion useful for?
drugs with a small therapeutic window
What is the main feature of a long term IV infusion?
at steady state the rate of infusion equals the rate of elimination
What is the relationship between steady state concentration and rate of infusion?
proportional - if double the rate of infusion then double the steady state concentration
In multiple dosing what is the result of giving the drug every half life?
two-fold variation in plasma concentration
In long term IV infusion how long does it take to reach steady state?
7 half lives
What is a loading dose?
An initial dose that is higher than the infusion amount so that steady state is reached earlier
What is first pass hepatic metabolism?
all drugs that are given orally go first to the liver where they will undergo metabolism before reaching systemic circulation
Why is the peak concentration of oral administration not as high as IV administration?
because there is elimination during absorption, because not all of the drug will be absorbed and because some of the drug will undergo first pass hepatic metabolism
What is bioavailability?
the proportion of active drug which enters the systemic circulation
What is bioavailability for IV administration?
What affects bioavailabilty?
how much drug is absorbed and how much drug undergoes metabolism