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PHARMACOLOGY | Drug Distribution - Coggle Diagram
PHARMACOLOGY | Drug Distribution
Passage of a drug from the blood circulation to the interstitial fluid or the cells of the tissues.
Movement of the drug until equilibration between unbound drug in plasma and tissue fluids
Very large drug molecules (protein) cannot cross the basal membrane of the capillaries to the interstitial space, therefore, they remain confined to the circulation. Results in high concentrations in plasma. Meanwhile, small molecules drugs with non-polar properties can easily cross cell membrane, results in low plasma concentration.
Occur in 4 patterns
Non-homogenous
Homogenous
In plasma
Concentration in specific tissues
Compartments of drug distribution:
Fat
Plasma (intravascular)
Intracellular
Interstitial
Volume of distribution
The larger the Vd, more drug found in tissue
Smaller the Vd, drug confined in circulatory system
Factors affecting volume of distribution
Blood flow
Lipid solubility
pKa of drug
Affinity for different tissues
Disease states
Plasma protein binding
Physiological barrier
Simple capillary endothelial barrier
Simple cell membrane barrier
Blood brain barrier
Placental barrier