Absorption:drug transport Movement of Drugs across membranes: Active Transport:i)energy dependent;ii)saturable;iii) against an electrochemical gradient;iv)selective carrier- mediated. Facilitated Diffusion:i)requires NO energy;ii)saturable;iii) NEVER against an electrochemical gradient;iv)selective carrier-mediated. Pinocytosis:Drugs of large molecular weight(MW 900)may enter cells by pinocytosis or phagocytosis. Passive Diffusion:This is the MOST COMMON mechanism for drug transport.Lipid-soluble drugs permeate across the cell membrane by passive diffusion between the lipid molecules of the cell membrane
Absorption: drug transport • Movement of Drugs across membranes: • Active Transport: i) energy dependent; ii) saturable; iii) against an electrochemical gradient; iv) selective carrier‐ mediated. • Facilitated Diffusion: i) requires NO energy; ii)saturable; iii) NEVER against an electrochemical gradient; iv) selective carrier‐mediated. • Pinocytosis: Drugs of large molecular weight (MW > 900) may enter cells by pinocytosis or phagocytosis. • Passive Diffusion: This is the MOST COMMON mechanism for drug transport. Lipid‐soluble drugs permeate across the cell membrane by passive diffusion between the lipid molecules of the cell membrane
Drug transport across bio-membrane Passive transport does not involve chemical energy, but requires a concentration gradient across the membrane.Passive transport includes simple diffusion and facilitated diffusion. Extracellular space Lipid bilayer (cell membrane Intracellular space TIME
Drug transport across bio‐membrane • Passive transport does not involve chemical energy, but requires a concentration gradient across the membrane. Passive transport includes simple diffusion and facilitated diffusion. From Wikipedia
Drug transport across bio-membrane Facilitated diffusion is a form of transport that requires carriers,although it does not require energy and dependents on concentration gradient.Because carriers are involved,facilitated diffusion can be saturated and there exists competitive inhibition. Extracellular space Protein channel ell membran Carrier proteins Intracellular space
Drug transport across bio‐membrane • Facilitated diffusion is a form of transport that requires carriers, although it does not require energy and dependents on concentration gradient. Because carriers are involved, facilitated diffusion can be saturated and there exists competitive inhibition. From Wikipedia
Drug transport across bio-membrane Active transport moves molecules from lower concentrations to higher concentrations.It is i)energy dependent;ii) saturable;iii)against an electrochemical gradient;iv)selective carrier-mediated.In Primary active transport,energy is generated from the conversion of ATP to ADP and used to pump the transport of molecules such as Na+and K+(e.g., Na+-K+-ATPase). Extracellular space ●Sodlum Potasslum Na Cell membrane tracellular space
Drug transport across bio‐membrane • Active transport moves molecules from lower concentrations to higher concentrations. It is i) energy dependent; ii) saturable; iii) against an electrochemical gradient; iv) selective carrier‐mediated. In Primary active transport, energy is generated from the conversion of ATP to ADP and used to pump the transport of molecules such as Na+ and K+ (e.g., Na+‐K+‐ATPase). From Wikipedia
Drug transport across bio-membrane In antiport,such as sodium-calcium exchanger,two species of ions are pumped in opposite directions across a membrane. One of these species flows from high to low concentration, which generates entropic energy to drive the transport of the other ion from a low concentration region to a high concentration. Extracellular space Na" Cell membrane Intracellular space
Drug transport across bio‐membrane • In antiport, such as sodium‐calcium exchanger, two species of ions are pumped in opposite directions across a membrane. One of these species flows from high to low concentration, which generates entropic energy to drive the transport of the other ion from a low concentration region to a high concentration. From Wikipedia