Hyoscine hydrobromide

Used for motion sickness

• hyoscine hydrobromide is a muscarinic acetylcholine receptor antagonist
  
  
• hyoscine hydrobromide is readily available in the community as an over-the-counter medication for nausea and vomiting
  • as Joy-rides and Kwells are on sale to the public
    
    
• overdose of this anticholinergic medication can lead to toxicity including disorientation, agitation, visual and auditory hallucinations, tachycardia, arrhythmias including QTc prolongation, visual disturbances and urinary retention (1)
  
  
• have been a small number of reports of serious and life-threatening anticholinergic side effects associated with hyoscine hydrobromide patches, particularly when used outside the licence (2)
  • licensed indication of a hyoscine hydrobromide patch (Scopoderm 1.5mg Patch or Scopoderm TTS Patch) is for the prevention of motion or travel sickness symptoms (for example nausea, vomiting and vertigo) in adults and children aged 10 years of age or older. Each patch should be used for 72 hours
  • there is widespread use of hyoscine hydrobromide patches outside the licence. Usage outside the licence includes:
    • indications other than motion or travel sickness
    • use in children younger than 10 years of age
    • cutting patches (this may adversely affect the bioavailability of the drug)
    • application of more than one patch at a time
    • continuous use without a break
    • long-term use
  • hyoscine hydrobromide patches are often recommended in clinical guidance for indications other than motion or travel sickness. These indications (which are outside the licence) include:
    • the management of hypersecretion or hypersalivation in diverse clinical populations; for example, in patients with complex multiple disabilities or cerebral palsy, patients on ventilation, patients with Parkinson’s disease, patients requiring palliative care, and patients with drug-induced hypersalivation
    • the management of nausea and vomiting; for example, in patients after surgery or in patients with cancer
  • reports of serious or life-threatening anticholinergic side effects
    • children and elderly people are more susceptible to anticholinergic toxicity secondary to hyoscine hydrobromide
    • hyoscine hydrobromide crosses the blood–brain barrier it has both central and peripheral actions, causing a range of anticholinergic side-effects including:
      • hyperthermia,
      • urinary retention,
      • dry mouth,
      • disturbances of visual accommodation (blurred vision),
      • mydriasis,
      • skin irritation,
      • generalised rash,
      • somnolence,
      • dizziness,
      • memory impairment,
      • disturbances in attention,
      • restlessness,
      • disorientation,
      • confusion,
      • hallucinations,
      • delirium,
      • seizures,
      • coma,
      • respiratory paralysis
    • side effects occurring after removal of the patch
      • after removal of the patch, hyoscine in the skin continues to enter the blood stream
      • side effects may therefore persist for up to 24 hours or longer after patch removal

Reference:

• Xuereb G, Calleja T, Borg J, Pace D. Unintentional overdose of hyoscine hydrobromide in a young child. BMJ Case Rep. 2020 Feb 11;13(2):e234029. doi: 10.1136/bcr-2019-234029. Corrected and republished in: Drug Ther Bull. 2020 Dec;58(12):189-191. PMID: 32051153; PMCID: PMC7035799.
• Drug Safety Update volume 16, issue 12: July 2023: 1.