Flashcards in Factors that complicate Pharmacokinetics Deck (12):
What are the two factors that complicate pharmacokinetics?
unusual drug behaviour and inter patient variability
When is variation in pharmacokinetics an issue?
when the drug has a narrow therapeutic window
What are the three ways that a drug can have unusual behaviour?
low bioavailability, slow distribution, drug saturates elimination processes
What is the problem with low bioavailability?
there will be a big variation in the amount of drug that reaches its destination
How do you deal with a drug with low bioavailability?
use another route of administration
What is the problem with slow distribution?
get a peak concentration that is much higher than normal
How do you deal with a drug with slow distribution?
give several smaller doses rather than one big dose
What is the problem with a drug which saturates elimination processes?
steady state is never reached with multiple dosing and increasing dose rate leads to disproportional increase in concentration
How do you deal with a drug which saturates elimination processes?
adjust and monitor dose
What causes inter patient variability?
age, genetic factors, disease, drug-drug interactions
How does age cause inter patient variability?
renal function is different and phase I and phase II metabolism is different