What is the recommended use of a scopolamine (anticholinergic) patch for preventing seasickness?

Recommended Use of Scopolamine Patch for Preventing Seasickness

Scopolamine transdermal patches should be applied behind the ear at least 4-6 hours before sea travel for optimal prevention of motion sickness, with each patch providing effectiveness for up to 3 days. 1

Application and Timing

• Apply one scopolamine transdermal patch to the hairless area behind one ear at least 4-6 hours before antiemetic effect is needed 1
• For faster protection when immediate effect is needed, consider combining the patch with oral scopolamine (0.3 or 0.6 mg) which provides therapeutic levels starting as early as 30 minutes after administration 2
• Each patch contains 1.5 mg of scopolamine and delivers approximately 1 mg over 3 days at a rate of about 5 μg/hour 1, 3
• The patch includes a priming dose (140 μg) in the adhesive layer to accelerate achievement of steady-state blood levels 3

Efficacy and Duration

• Scopolamine patches have been shown to reduce the incidence and severity of motion sickness by 60-80% compared to placebo 3
• Therapeutic plasma concentration (approximately 50 pg/mL) is achieved after about 6 hours, with steady state levels of approximately 100 pg/mL reached 8-12 hours after application 3
• Each patch remains effective for up to 3 days (72 hours) 1
• For voyages longer than 3 days, remove the first patch and apply a new one behind the opposite ear 1, 3

Proper Use and Handling

• Only wear one patch at a time 1
• After applying the patch, wash hands thoroughly with soap and water to prevent accidental transfer of medication to eyes (which can cause pupil dilation) 1
• If the patch becomes displaced, discard it and apply a new patch behind the other ear 1
• Avoid touching the patch while wearing it, as pressure may cause scopolamine to leak from the edges 1
• Upon removal, fold the used patch with the sticky side together and discard in household trash 1

Common Side Effects and Precautions

• Dry mouth occurs in approximately 50-60% of users 3
• Drowsiness may occur in up to 20% of users, though this is less frequent than with oral antiemetic alternatives 3
• Contact dermatitis occurs in approximately 10% of users 3
• Transient impairment of ocular accommodation may occur, particularly if medication is transferred from fingers to eyes 3
• CNS effects including confusion or hallucinations are rare but more common in elderly patients 3, 4

Clinical Pearls

• Long-term studies show sustained effectiveness over years of intermittent use without development of tolerance 5
• Therapeutic failure (seen in 20-30% of users) may be related to insufficient plasma concentrations 6
• Scopolamine patches are most effective against motion sickness 8-12 hours after application, so plan accordingly for optimal protection 3
• For patients who don't respond adequately to the patch alone, a combination approach with oral scopolamine may be considered for initial protection 2

Contraindications

• Avoid use in patients with narrow-angle glaucoma, urinary retention, or known hypersensitivity to scopolamine 4
• Use with caution in elderly patients who may be more susceptible to anticholinergic side effects 3
• If side effects become intolerable, remove the patch immediately and wash the application site thoroughly 1