PCL102H1 Lecture Notes - Lecture 8: Bile Acid, Fetus, Exocytosis
Document Summary
Lecture 7 and 8 mechanisms of drug absorption. Transcytosis may occur: other capillaries have fenestrations, transient or long-lasting openings. Intrathecal injection into csf is an effective way to deliver drugs to the brain: placenta, peritoneum, and lung barriers. Winter 2014: assume all drugs cross the placenta, limited maternal blood flow into placenta equilibrium between of drug between mother and fetus takes 10-15 minutes, peritoneum cells have macular junctions. Large molecules use pinocytosis to cross peritoneum cells: alveolar cells are connected by occluding zonulae, but it is so thin that fenestrations can occur. Lipid and water soluble molecules can cross: functional barriers (transporters, active transport to pump out drugs, e. g. Abc protein (atp binding cassette: p-glycoprotein/mdr (multiple drug resistance) Passive diffusion: water soluble compounds, depending on the molecular weight/size, may pass between cells or use aquaporin channels, lipid soluble compounds rate of diffusion depends on. [drug] to rate of diffusion is not linear hard to regulate drug dose.
