Physiological Barriers
Physiological Barriers Physiological Barriers to Distribution of Drugs contains a membrane (or a barrier) with special structural features which can be a permeability restriction to distribution of drugs to some tissues Some important simple and specialized physiological barriers are: 1. Simple capillary endothelial barrier 2. Simple cell membrane barrier 3. Blood-brain barrier 4. Blood-CSF barrier 5. Blood- placental barrier 6. Blood-testis barrier 1.Simple Capillary Endothelial Barrier: All drugs, ionized/unionized, with a molecular size less than 600 Daltons, diffuse through this barrier into the interstitial fluid Only drugs bound to blood components are restricted because of large molecular size of the complex 2.Simple Cell Membrane Barrier: Simple cell membrane is similar to the lipoidal barrier in the GI absorption of drugs The physicochemical properties that influence permeation of drugs across such a barrier are summarized below: 3.Blood-Brain B...