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D.3 Opiates

Yeet

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Analgesic properties of opiates

  • Mild Analgesics
    • Drugs acting to relieve pain at the source (do not affect central nervous system)
  • Opiates
    • Aka opioids
    • Strong analgesics - don’t kill pain at source
    • Kills pain by affecting central nervous system (brain… @rambo)
  • Opiates interact with opioid receptors in the brain
  • Therefore, they are classified as narcotics
  • Strong analgesics must enter the brain (by the definition of narcotic)
    • Therefore, they must pass through the blood-brain barrier, which is a lipid (non-polar, for u non-bio kids like me) barrier

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Structure and synthesis of opioids

  • Codeine
    • Often used with a non-narcotic drug
    • More mild than other narcotics
    • Slows down digestive process (side effect)
  • Morphine
    • Most well known
    • Reduces pain
    • Leads to dependence
    • Causes body to release endorphins, so the influx of hormones that the body releases after to counter it causes the “lows” to feel lower → dependence
  • Diamorphine
    • Highest potential of causing addiction
    • Euphoria
    • Only legal in a few countries for extreme relief of pain (not your country ok)

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The 3 main opioids in the syllabus

  • Codeine
    • Methylation of morphine
    • Less polar and more effective (passes through blood-brain barrier more easily), but lower bioavailability
  • Diamorphine
    • Esterification of morphine
    • Reduces polarity significantly - more passing through blood-brain barrier
    • Ethanoic acid + morphine → diamorphine + water
    • Don’t do this at home kids

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Nature of science - Morphine

  • Morphine was isolated in 1803
  • American Civil war in 1860
  • Addiction and dependence was a severe side effect for many soldiers, as the TI wasn’t very well understood at that stage
  • Harmful side effects were not discovered until later

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Pain management

  • WHO have a 3-step analgesic ladder (the number of brain cells I have)
    • Supposed to encourage better management of pain
  • 1: Use mild analgesics
    • Paracetamol, Nurofen, etc
  • 2: Add a weak opioid such as codeine or tramadol
  • 3: In severe, unretractable pain, use strong opioids such as morphine, methadone or diamorphine

Only problem is that they haven’t added a level to deal with the pain of doing IB

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Side effects of strong analgesics

  • Constipation (is sometimes therefore used to treat diarrhoea
  • Suppression of the cough reflex (not the gag reflex, let’s be mature)
  • Constriction of pupil
  • Feeling of well-being and contentment
  • Lessening fear and tension
  • If drug is taken via injection
    • HIV and hepatitis

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Narcotic effects and addiction

  • The word ‘narcotic’ is derived from the greek word for numbness or stupor
  • They depress brain function, induce sleep and are potentially addictive
  • Diamorphine is the most addictive (heroin)
  • Short term;
    • Contentment
    • Dulling of pain
    • Reduction of fear and tension
  • Long term;
    • Dependence
    • Increased tolerance
    • Money → life of crime (yes, this is an actual syllabus point)
    • Blood-transferrable infections (HIV, Hepatitis, etc)

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Narcotic effects and addiction cont’d

  • Helping heroin addicts break their dependence is very difficult
  • Sometimes, an alternative opioid is administered to reduce their dependence on one substance alone, helps their body adjust to withdrawal
  • Ethically controversial, but empirical data shows that it does help
  • Don’t do drugs kids, please