Pharmacokinetics

• Pharmacokinetics 


  -quantitative study of drug movement

  -Study of process by which drug is absorbed

  -absorption, distribution, metabolism and excretion of drugs
• Pharmacokineti properties


  -affected by the route of administration
• the principles of adme

  • absorption-how will it get in
  • metabolism-how is it broken down (liver)
  • distribution-where will it go (transporters)
  • excretion-how does it leave
• Absorption 


  -process by which drug enters system

  -takes place from different routes
• Bioavailability 


  -fraction of administered drug (unchanged form)
• Biological Membrane 


  -outermost layer of the cell

  -contains phospholipid bilayer
• Transport across the cell membrane/biological membrane

  • Passive transport
  • passive diffusion
  • facilitated diffusion
  • active transport
  • primary active transport
  • secondary active transport
  • endocytosis
• Passive transport


  -does not require energy
• Passive diffusion 


  -drug molecules are transported by diffusion process

  -does not require energy

  -directly proportional to the concentration gradient across the membrane
• Facilitated diffusion 


  -drug molecules are transported with the help of carrier protein
• Active transport 


  -transport of molecules against concentration gradient

  -obtained from ATP hydrolysis or electrochemical gradient (Na+ , H+)
• Primary Active Transport 


  -membrane transport that couples with ATP hydrolysis

  • ABC transporters
• secondary active transport 


  -requires ion electrochemical gradient

  -downhill movement of one species drives the uphill movement of the other

  -can be symport
• Endocytosis


  -cell transport molecules into cells

  -uses energy

  -includes pinocytosis (cell drinking) & phagocytosis (cell eating)