Lecture 1.5: Uptake and Distribution Flashcards
What form of drug will have an effect on the brain?
non ionized, lipophilic
What form of drug will be excreted by kidneys?
ionized
What is happening in the liver?
non ionized to ionized, lipophilic to hydrophilic
Degree of ionization depends on:
dissociation constant and pt’s pH
Give acidic drug to acidic pt:
give lower dose
Give basic drug to acidic pt:
give higher dose
Ion trapping example
give basic drug to alkalemic mother - nonionized drug passes to fetus
fetus pH is acidic - ionizes drug, can’t pass back to mother
Difference in pH of mother/fetus
fetus more acidic than mother
Protein binding trends
acids bind to albumin (main one)
bases bind to alpha 1 glycoproteins
Drugs that are highly protein bound:
warfarin, propranolol, phenytoin, diazepam
What is clearance
the volume of plasma cleared by metabolism and excretion
What is first order kinetics
drug cleared at rate proportional to amount in plasma
What is zero order kinetics
drug cleared at constant rate per unit of TIME
Eg: ASA, Dilantin, ETOH
Hepatic clearance
if hepatic extraction is > 0.7, depends on hepatic blood flow
(perfusion dependent elimination)
If hepatic extraction ration < 0.3
hepatic clearance depends on enzyme activity
capacity dependent elimination
Renal clearance
most important organ for eliminating ionized drugs