Physiological Properties Affecting Drug Distribution

Physiological Properties Affecting Drug Distribution include blood flow, tissue permeability, protein binding, and body water content.

Physiological Properties Affecting Drug Distribution

The distribution of a drug in the body is influenced by several physiological properties:

1. Lipid Solubility

   • Highly lipid-soluble drugs (e.g., diazepam, propofol) distribute more readily into lipid-rich tissues like the brain and adipose tissue.

2. Ionization State

   • The ionization of a drug affects membrane permeability.
   • Acidic drugs accumulate in acidic tissues (e.g., stomach), while basic drugs accumulate in basic tissues (e.g., liver).

3. Molecular Size and Shape

   • Smaller and more compact molecules cross membranes more easily and distribute faster than larger, bulkier molecules.

4. Protein Binding

   • Many drugs bind to plasma proteins (e.g., albumin), limiting their availability for tissue distribution.
   • Only unbound (free) drugs are available for active distribution.

5. Blood Flow

   • Organs with high blood flow (e.g., liver, kidneys, brain) receive drugs more rapidly than low-perfusion tissues (e.g., adipose tissue).

6. Capillary Permeability

   • The ease with which a drug crosses capillary membranes influences its distribution.
   • Barriers like the blood-brain barrier (BBB) restrict drug entry, while other capillaries (e.g., in the liver) allow easier passage.

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