W3: The concept of drug distribution Flashcards
Definition of drug distribution:
_________ of a drug between ____ , ______ and tissues of the body such as fat and muscle.
Reversible transfer of a drug between the blood and the extravascular fluids and the tissue of body
The flow of the drug is from blood -> _________ -> __________ -> cells
blood -> interstitial fluid -> intracellular fluid -> cells
Name the 4 water compartments in the body: GO
- plasma
- interstitial fluid
- intracellular fluid
- fat
Bound drug molecules = drugs that bind to_____
drugs that bind to plasma proteins
Only ____ drugs can move between compartments.
Only free drugs can move
so, what the hell is interstitial fluid?
The water/fluid that surround the cell. Its in the extracellular environment.
EASY. WHAT IS INTRACELLULAR FLUID?
FLUID INSIDE CELL LAH
What two components make up the extracellular fluid (ECF)?
Interstitial fluid and intravascular fluid (plasma)
The movement of the drug into the compartments depend on ________ of drug.
Concentration of the drug
The drug will be moved back and forth until ________
Equilibrium is achieved
Volume of distribution is the
volume into which the drug is distributed to provide the same concentration as it currently is in blood plasma.
Small volume of distribution means that the drug would ______________
drug would remain in the systemic circulation
Large volume of distribution means that the drug ___________
drug can be found in volumes outside of systemic circulation = widely distributed
What contributes to the low Vd for drug?
High degree of plasma protein binding
What contributes to the high Vd of a drug?
The drug is most likely highly lipophilic = greater ability to diffuse through membrane
Ideally, when a drug has Vd = 40L , it will distribute _____
it will distribute into cells
Vd = 3L means ____
drug stays in plasma, bind to plasma protein
Vd = 12L means _____
drug stays in extracellular fluid but cannot penetrate cells
Vd = >40L means _____
Drug sequestered in extravascular lipid compartment
The drug heparin has a Vd= 3L, what does this tell you?
Hint: Distribution, compartment, plasma protein
It remains in only the blood, the systemic circulation, this counts as one compartment.
Heparin binds to plasma protein
The drug aminoglycosides has a Vd = 14L, what does this tell you?
(Hint: Distribution, compartment, molecule properties)
The drug can distribute to blood and extracellular fluid (interstitial fluid) = 2 compartments
Drug is hydrophilic and can move through endothelial gap junctions of capillaries.
