Chapter 6

• Psychopharmacology = study of how drugs affect the nervous system and behavior
• What are psychoactive drugs?


  substances that:

  • alter mood, thought or behavior
  • are used to manage neuropsychological illness
  • are taken recreationally
  • are commonly abu
• What are the drug administration routes?

  enteral = via digestive system (slow)

  parenteral = not via digestive system (faster)
• drug asministration route - enteral

  = via the digestive system (slow)

  • oral: through mouth (most convenient)
  • rectal: from the rectum (weak bases)
  • gastric: through stomach (weak acids)
  • buccal/ sublabial: between lip & gum
  • sublingual: under tongue (hydrophilic)
• Drug administration route - parenteral

  = not via digestive system (faster)

  • subcutaneous: under skin
  • intramuscular: into muscle
  • intravenous: into the atery (hydrophilic)
  • inhalation: into lungs
  • transdermal: through skin (patches)
  • spinal or intracranial: into spinal cord or brain (e.g. epidural, intrathecal) -> no barriers: directly into CSF, so only low dose needed
• With each obstacle eliminated in route to the brain, a drug's dosage can be reduced by factor of ~10 to induce same effect

  e.g. orally 1000µg =inhaled 100µg = intravenous 10µg
• Where do drugs end uo in most routes of administration?

  in the blood stream
• Where do the drugs have to be transferred to be able to act in the brain?

  from blood stream to extracellular fluid

  Note: must overcome blood-brain barrier
• What is the blood-brain barrier?

  tight junctions between the cells and blood vessels in the brain block passage of most substances

  • only very small uncharched molecules can pass (e.g.O2, CO2)
  • = active transport system (membrane proteins) for amino acids, glucose & fats