W7 - Distribution Flashcards
What is the volume of distribution
Volume of fluid required to contain the total amount of drug in the body at the same concentration as that present in the plasma
What is the unit of Vd
Litres but can be normalised against body weight so become Litres/Kg
What is the minimum amount of Vd
it cannot be smaller than the physiological volume of intravascular plasmsa which is roughly 3L
What does the distribution of drugs depend on
Physiochemical feature
Pharmacological features
Blood Flow in organ/ Tissue
Barriers of organ / tissue
what are the 2 main physiochemical features of the drug
size of drug molecule
pKa of drug
What fraction of a drug is therapeutically active
only unbound fractions of drug are therapeutically active
what is the rate at which a drug is distributed dependent upon
the rate at which a drug is distributed to various organs depends on the proportion of cardiac output to the target.
