ADME

• What is absorption?

  How the drug is taken into the plasma following administration.
• How is absporption affected?

  Nature of the drug, Route of administration, Perfusion of the area, condition of the patient.
• How do drugs move around the body?

  By passive diffusion.
• Step 1: Absorption?


  Drug passes through small pores or ion channels (e.g. calcium),
• Step 2: absorption?


  Carrier mediated (active transport). Drug binds weakly to carrier molecule in cell membrane. Released once carrier has crossed the membrane.
• Step 3: Absorption?


  Passive diffusion- Drug moves from area of high concentration to area of low concentration, until equal concentrations of the drug are on either side.
• what is passive diffusion?


  Passing through lipid layer of a cell membrane. Drug needs to be lipid soluble to pass through wall.
• what is distribution?


  How the drug is transported to the site of action (mainly via plasma or diffusing across the fluid compartments of tissue.)
• How is distribution affected?


  Nature of drug, extent of which the drug is bound to a plasma protein and perfusion of the target organ.
• Where can distribution occur?

  lymph, CSF, Lymph, Aquous Humor.
• main fluid of distribution?

  plasma
• what is in plasma?


  contains dissolved proteins e.g. albumen which drugs binds to. Plasma leaks out into tissue from capillaries.
• What organs of the body receive the drug first?

  heart, liver, kidney and brain.
• Step one: Distribution?


  Intestinal fluid- Fluid that bathes cells/tissue, found outside cells and blood vessels.
• Step 2: Distribution?


  Blood plasma= intravascular fluid, found within blood vessels.
• Step 3: Distribution?


  Tissue
• Step 4: Distribution?


  Receptors- drug targets specific receptor cells.
• what are receptors?


  protein molecule found on the cell.
• what are receptors responsible for?


  Receiving chemical impulses from drugs administered and receptors respond to it.
• what is the purpose of distribution?

  To allow the drug to reach desired 'target tissue' so it can have its effect.
• What is metabolism?


  bodies ability to change a drug from the form in which it was administered into a form that can be eliminated by the body.
• what factors affect metabolism?


  Species, drug interactions, repeated exposure to the drug and liver function.
• where does metabolism occur?

  Liver, lungs and kidneys.
• what is first pass metabolism?

  Drug is absorbed across the GI tract where is it transported via the hepatic portal vein the liver where metabolism occurs.
• What does metabolism do to the drug?

  it will biotransform drugs as it would to attempt to remove foreign substances.
• What 3 changes will metabolism do to a drug?

  inactivate (Decrease activity) of drug.

  
  

  Add molecule to allow the excretion of a drug.

  
  

  Convert a toxic substance into a non-toxic substance.
• What is phase one of metabolism called + general overview?


  metabolism- Where enzymes act on a drug transforming it to produce a metabolite.
• During phase one, what reactions cause a metabolite?

  Oxidisation, Reduction + hydrolysis.
• Oxidisation?


  an oxygen atom is added to compound.
• Reduction?


  A hydrogen atom is added to compound.
• Hydrolysis?


  Water is added to compound.
• What is phase two of metabolism called?

  Conjugation.
• What occurs during conjugation?

  Metabolite is bound to another molecule making it more water soluable.
• what compounded is added during phase two of metabolism?

  Glucuronic acid.
• What effect does phase 2 of metabolism have on cats?

  Cats are unable to conjugate some drugs due to reduced ability to form glucuronic acid, which slows ability to excrete the product and increases its toxicity.
• what factors affect elimination?

  Organ function.
• where does elimination occur?

  kidneys in urine or fat-soluable drugs are excreted in faeces via liver.
• Areas the drug be excreted from?

  Mammary glands, intestinal tract, liver, sweat glands, salivary glands, skin.
• Step one: Renal excretion?


  Drugs are filtered from the body into urine by the kidneys.
• Step two: renal excretion?

  Small molecules are forced through the Bowmans capsule by ultrafiltration.