When a foreign substance enters the body, it does something to the body, and the body does something to it.

  • Pharmacokinetics: How the body affects a drug
      • Such as what its metabolites are
      • Or, how fast the substance is broken down
    • Ingestion: How the body takes in the substance
      • Called routes of administration (ROA)
      • Inhalation
      • Swallowing
      • Sublingual (the mucous membranes in the mouth)
      • Dermal (skin contact)
      • Intravenous (IV)
      • Intramuscular (IM)
      • And more
    • Absorption: the drug makes its way into the body
      • Fast absorption makes a substance more addictive
      • Slow absorption usually means that a drug is more therapeutic, exceptions include panic attack treatment
    • Distribution
      • Where a substance goes after entering the body
    • Metabolism: the biochemical way by which the body functions
      • People with a slow metabolism tend to weigh more
      • It is, in a sense, how fast the body process runs
    • Metabolic: The body breaking down and processing compounds
    • Metabolite: a chemical produced as a byproduct of another chemical being broken down
      • Metabolites can themselves be psychoactive, or not
    • Half-life: the amount of time, from ingestion, it takes for half of the drug to leave the body
      • After 5-7 half-lifes (most say 5.5), the drug is considered gone
    • Excretion: The body getting rid of the drug
      • Some drugs take a full week of abstinence to leave the body, others do so in minutes

  • Pharmacodynamics: how a drug affects the body
    • For example…
      • Alcohol (ethanol) acst as a neurotransmitter and bind to a receptor, causing ion channels to artifically open or close
      • Donepezil prevent the enzyme acetylchollinesterase from breaking down the neurotransmitter acetylcholline as fast
      • Chemotherapy chemicals weaken the immune system
  • Lipophilic: a compound dissolves in fat
    • It is “soluable” in fat (lipid)
  • Lipophobic: a compound that doesn’t dissolve in fat
    • It is “insoluble” in fat (lipid)
  • Endothelial cells: fat (lipid) cells that line our blood vessels throughout the entire vascular system,, facilitating such important functions as…
    • Tissue repair
    • Release of NO, which acts as a neurotransmitters
    • Allowinf blood vessels to enlarge or detract their diameter to ideally suit blood flow
    • If a chemical can dissolve in these cells, it can make its way into the brain, but that does not necessarily mean it is psychoactive
  • Blood-brain barrier: a dense, protective barrier that acts as a gatekeeper for the brain
    • Composed of endothelial cells
    • Lipophilic chemicals enter the brain
  • Neurotoxic: a substance that damages brain cells (neurons or glia)
    • Oftentimes, this is excitotoxicity: toxicity due to too much excitatory neurotransmission
    • For example…
      • MDMA is toxic to serotonergic neurons
      • Methamphetamine is toxic to dopaminergic neurons
  • Cardiotoxic: significantly toxic to the heart
    • For example…
      • Cocaine
      • Non-therapeutic doses of stimulant medications
      • fenfluramine
  • Hepatotoxic: significantly toxic to the liver
    • For example…
      • Alcohol (ethanol), due to its metabolite: acetaldehyde
      • Acetaminpohen
      • Aspirin
      • Statins
  • Neurogenic/neurotrophic: significantly helping the brain create new cells, and maintain old cells
    • Exercise
    • Meditation
    • Most antidepressants
    • Not always desirable, as cancer is accelerated and unregulated cell production
  • LD50: the amount of a drug that would kill 50% of a sample
  • Endogenous: created by the body, for our purposes, by the central nervous system CNS)
    • endorphin
    • endocannabinoid
  • Exogenous: created outside of the body, then brought in

  • Neurotransmitters: chemicals in the brain that neurons and glia use to communicate
    • Inhibitory: decrease frequency of messages passed between brain cells
    • Excitatory speed up frequency of messages passed between brain cells
    • The receptor type that a neurotransmitter binds to, is much more informative than the neurotransmitter, for example…
      • The dopamine D2 receptor is inhibitory, but the dopamine D1 receptor is excitatory
      • The serotonin 5-HT1a receptor is inhibitory, but the serotonin 5-HT3 receptor is excitatory
    • Monoamines: neurotransmitters most thought involved in mental illness
      • Dopamine: associated with cognition, novelty, movement, and prolactin (used for making milk)
      • Serotonin: mainly deals with mood, appetite, and anxiety
      • Norepinephrine (aka noradrenaline): mentally exciting
      • Epinephrine (aka adrenaline): physically exciting
      • Work mostly on signal proteins (g-protein coupled receptors)
    • Amino acids
      • Gamma-amino butyrate acid (GABA): the main inhibitory neurotransmitter in the nervous system
      • Glutamate: the main excitatory neurotransmitter in the nervous system
      • Mostly work on channel proteins (ligand-gated ion channels)
    • Acetylcholline: involved in aspects of cognition and muscle use
    • Peptides: large chains of chemicals
      • Endogenous morphine-like chemicals (known as endorphins)
        • More than 20 morphine-like chemicals are produced in the body
      • Hormones
        • Cortisol
        • Estrogen
        • Testosterone
    • Unconventional neurotransmitters
      • They behave strangely
      • Endocannabinoids (endogenous cannabinoids)
      • Various gases, such as NO

The body systems overlap. There is no absolute line where one ends, and another begins. Below is

  • Nervous system: responsible for voluntary and involuntary bodily actions
    • Central nervous system (CNS): the part of the nervous system that’s encased in the bone of the skull and the spine
      • Makes decisions
      • Neuron: a specialized cell that has axons and dendrites
      • Glial cell: the cell type of that supports neurons
        • Three main kinds: astrocytes, ogliodendricytes, microglia
    • Peripheral nervous system (PNS): the part of the nervous system outside of the bone of the skull and spine
      • Somatic Nervous System
      • Autonomic Nervous System (ANS): regulates the internal (bodily) state
      • Somatic Nervous System (SNS): interacts with the external environment
      • Has neurons
      • Has shwann cells (a glial cell)
      • Serves as a middleman between the CNS and other body parts
  • Endocrine system: the system of the body dealing with hormones
    • Largely indicated in sexuality
  • Circulatory system: deals with providing nutrients to cells, and removing waste
    • Powered by the heart
  • Respiratory system: involved in breathing, including carrying oxygen to cells, and removing waste
    • In this way, works together with the circulatory system
  • Immune system: fights infections
    • White blood cells
  • Digestive system: breaks down and processes food and water
    • Nutrients can be absorbed even in the intestinal tract
    • Vyvanse (lisdeamphetamine) is absorbed near the end of the digestive system

Sources: Dr. Kevin Davis, Dr. Theodore Papperman, Stahl’s Essential Psychopharmacology, Ben Komor, http://www.healthline.com, https://www.dea.gov, http://www.fda.gov, http://americanaddictioncenters.org, Biopsychology, http://medical-dictionary.thefreedictionary.com/, http://whs.rocklinusd.org/documents/Science/Lethal_Dose_Table.pdf, https://www.ncbi.nlm.nih.gov/books/NBK26848/, http://www.nutritionmd.org/health_care_providers/gastrointestinal/hepatoxicity.html