Factors that complicate Pharmacokinetics Flashcards
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
What are the two types of drug-drug interactions?
pharmacodynamic (no affect on concentration) and pharmacokinetic (affect on concentration)
