Drug Distribution Flashcards
For a drug to be active it must______
Leave the circulation and enter the inter or intracellular spaces
Plasma Protein Binding
The degree to which medications attach to proteins within the blood
Less bound drug is ______
More efficiently able to diffuse into cell membranes
Blood proteins that bind to drugs
Serum albumin, lipoprotein, glycoproteins and alpha, beta and gamma globulins
An increase in unbound drugs _______in toxicity
Increases
Only unbound drugs are_______
Biologically active
The binding of drugs to proteins in the blood is ______
Reversible
Tissue Perfusion
Passage of fluids from the circulatory system or lymphatic system to an organ or tissue
Lipid soluble drugs enter_____
Highly perfused tissues such as lungs, kidney, liver, heart and brain
What happens if a lipid soluble drug is given to a person with more adipose tissue
The drug is stored in the fat and acts as a reservoir of the drug
Volume of Distribution
the degree to which a drug is distributed in body tissue rather than the plasma
Low Volume of Distribution
Drug stays in vasculature and does not enter tissues
High Volume of Distribution
Lipid soluble drugs will enter brain, liver
What is the VOD for 1g of drug
1000mg/8L = 125 mg/L
Metabolism of drug
Hepatic
Removal of drug
Renal
What is clearance of a drug measured in
ml/min
In renal what is clearance dependent on
Urine flow and concentration
In hepatic what is clearance dependent on
Bilary excretion and metabolism
Half-life
Amount of time a drugs plasma concentration drops from maximum to half
Half-life duration
4 hours
What does the half-life depend on
VOD and clearance
An increase in half-life
Increases plasma concentration
Increases toxicity
Decrease in clearance
Increase in VOD
Steady State Concentration
Overall intake of a drug is fairly in a dynamic equilibrium with its elmination