What are the guidelines for using Scopolamine (hyoscine) for motion sickness and preoperative care?

Guidelines for Using Scopolamine for Motion Sickness and Preoperative Care

Scopolamine is indicated for the prevention of motion sickness and postoperative nausea and vomiting (PONV), with transdermal application being the preferred administration route for most clinical scenarios. 1

Motion Sickness Prevention

Dosage and Administration

• Transdermal application: Apply one scopolamine patch to the hairless area behind one ear at least 4 hours before antiemetic effect is required 1
  • Each patch delivers approximately 1 mg of scopolamine over 3 days
  • If therapy is required for longer than 3 days, remove the first patch and apply a new one behind the other ear

Efficacy

• Scopolamine is the most effective single agent for motion sickness prevention 2, 3
• Meta-analyses with Trial Sequential Analysis confirm scopolamine's superiority over placebo for reducing motion sickness-related nausea (RR 0.35; 95% CI 0.24 to 0.52) 4

Preoperative and Perioperative Use

PONV Prevention

• Timing: Apply one transdermal scopolamine patch the evening before scheduled surgery 1
• Duration: Remove the patch 24 hours following surgery 1
• Role in multimodal therapy: Consider as a second-line agent in combination with first-line antiemetics (5HT3 antagonists, dexamethasone, D2 antagonists) for patients with multiple risk factors 5

Considerations for Anesthesia

• Scopolamine is used in anesthesia primarily for:
  • Reduction of secretions
  • Minimization of vagal response (particularly important in infants and neonates) 5
• May prolong sedation and disorientation in patients under general anesthesia 5

Contraindications

1. Absolute contraindications:

   • Angle closure glaucoma 1
   • Hypersensitivity to scopolamine or other belladonna alkaloids 1
   • Pregnancy (crosses placenta) 6
   • Recurrent obstructive pneumonia with continuous sputum production 6

2. Use with caution in:

   • Elderly patients (higher risk of delirium and toxic psychosis) 6
   • Pediatric patients (increased sensitivity to neurological effects) 6, 1
   • Patients with open angle glaucoma (monitor intraocular pressure) 1
   • Patients with history of seizures 1

Adverse Effects

Central Nervous System Effects

• Memory impairment for new information
• Reduced attention and alertness 7
• Risk of psychiatric reactions including:
  • Acute toxic psychosis
  • Agitation
  • Hallucinations
  • Paranoia and delusions 1

Peripheral Effects

• Dry mouth (more common than with methscopolamine or cinnarizine) 8
• Blurred vision due to reduced visual accommodation (particularly problematic in hypermetropic individuals) 7
• Bradycardia 7
• Urinary retention 6

Special Considerations

1. Interindividual variability: Significant variation in response has been reported both between individuals and between different patch applications on the same individual 7

2. Pharmacokinetics:

   • Transdermal: Peak plasma concentrations reached after about 8 hours
   • Limited oral bioavailability (2.6% excreted unchanged in urine)
   • Metabolized primarily through glucuronide conjugation 2

3. PONV management: When used as part of multimodal PONV prophylaxis:

   • For patients with 1-2 risk factors: Consider as part of a two-drug combination
   • For patients with ≥2 risk factors: Consider as part of a 2-3 antiemetic regimen 5
   • If breakthrough PONV occurs, use a different class of antiemetic than used for prophylaxis 5

4. Caution with cumulative anticholinergic burden: Avoid combining with other medications with anticholinergic properties, especially in elderly patients 6

The transdermal formulation offers advantages over oral or parenteral administration by providing consistent drug levels over 72 hours and reducing the incidence of dose-dependent adverse effects like hallucinations, vertigo, and drowsiness 2.