Opioid misuse

• Overview:

  • Use of morphine, heroin and codeine
  • Central nervous system depressants that slow brain activity and relax muscles
  • Stimulate opioid receptors
• Physiological features:

  • Euphoria and reduced pain
  • Sedation
  • Respiratory depression
  • Miosis (constricted pupils)
  • Constipation
  • Skin warmth or flushing
  • Acute overdose will cause bradycardia and hypotension
• Psychological features:

  • Apathy - lack of interest or concern
  • Disinhibition
  • Drowsiness
  • Impaired judgement and attention
  • slurred speech
• Withdrawal symptoms:

  • Increased sympathetic nervous system activity
  • Rhinorrhoea
  • Lacrimation
  • Diarrhoea
  • Pupillary dilation
  • Piloerection
  • Tachycardia
  • Hypertension
• Investigations:

  • HIV and hepatitis B/C: due to the increased risk of blood-borne infection is greater through needle sharing
  • Tuberculosis testing
  • Urea & electrolytes
  • Liver function tests and clotting screen: to check hepatic function
  • Drug levels: to check for drug toxicity
• Screening questionnaires:

  • Drug abuse screening test (DAST)
  • CAGE-AID (adapted to include drugs)
  • Addiction severity index
  • Clinical opiate withdrawal scale (COWS)
• Management:

  • First line = methadone reduction - binds to opioid receptors
  • Buprenorphine reduction - binds to opioid receptors
  • Opioid overdose = naloxone
  • Naloxone is an opioid receptor antagonist - antagonizes the action of opioids, reversing their effects
• The classical clinical toxidrome of opioid overdose is a triad of:

  • reduced consciousness
  • respiratory depression
  • miosis
• It is important to also take paracetamol levels in a suspected overdose - could be mixed

  Some preparations of opioids come with paracetamol e.g. co-codamol
• Naloxone is an uncomplicated drug with a very safe side effect profile. The most commonly reported complications are the precipitation of acute withdrawal syndrome, and nausea and vomiting although these are usually short-lived.
• Acute lung injury following heroin overdose is a well-recognised complication and presents similarly to acute respiratory distress syndrome (ARDS).
• Untreated significant opioid overdose will ultimately result in death secondary to respiratory depression. This is the major cause of mortality in opioid overdose.