What is the use and application of the scopolamine (transdermal patch)?

Scopolamine Transdermal Patch: Clinical Applications and Use

Primary Indications

The scopolamine transdermal patch is FDA-approved for two specific indications in adults: prevention of motion sickness and prevention of postoperative nausea and vomiting (PONV). 1

Motion Sickness Prevention

• Apply one patch to the hairless area behind the ear at least 4 hours (preferably 6-8 hours) before the antiemetic effect is required 1, 2
• The patch delivers 1 mg of scopolamine over 3 days, with therapeutic plasma concentrations (≥50 pg/mL) achieved approximately 6-8 hours after application and steady-state levels (~100 pg/mL) reached at 8-12 hours 2, 3
• For faster protection when needed within 1 hour, combine patch application with oral scopolamine 0.3-0.6 mg, which provides therapeutic levels within 30-60 minutes while the patch takes effect 4
• The patch is significantly superior to placebo in reducing motion sickness incidence and severity by 60-80%, and more effective than oral meclizine or cinnarizine 2
• For journeys exceeding 3 days, remove the first patch and apply a new one behind the opposite ear 1

Postoperative Nausea and Vomiting (PONV)

• For surgeries other than cesarean section, apply one patch behind the ear the evening before surgery and remove 24 hours following surgery 1
• Transdermal scopolamine significantly reduces PONV risk versus placebo (RR=0.77,95% CI 0.61-0.98, P=0.03), with particular effectiveness for postoperative nausea (RR=0.59, P<0.001) and vomiting (RR=0.68, P<0.001) in the first 24 hours 5
• The American Society of Anesthesiologists guidelines support transdermal scopolamine for PONV prophylaxis, with evidence showing reduced nausea and vomiting without increased dizziness, drowsiness, fatigue, blurred vision, or dry mouth compared to placebo 6

Off-Label Uses in Palliative Care

Nausea and Vomiting Management

• Scopolamine patch (1.5 mg every 72 hours) is used off-label for refractory nausea and vomiting in gastroparesis and cancer-related symptoms, though clinical trial data supporting this indication are limited 6
• In cancer patients with inoperable bowel obstruction, scopolamine (hyoscine) has been studied as part of combination therapy, though octreotide showed superior efficacy in reducing nausea and vomiting 6
• For breakthrough nausea/vomiting, scopolamine transdermal patch may be incorporated as an additional agent from a different drug class when first-line antiemetics fail 6

Excessive Secretions in End-of-Life Care

• Scopolamine crosses the blood-brain barrier readily and causes significant CNS effects including drowsiness, disorientation, confusion, and potential delirium, making it less preferred than glycopyrrolate for managing excessive secretions 7
• Glycopyrrolate (0.2-0.4 mg IV/SC every 4 hours) is recommended as first-line over scopolamine for excessive secretions, particularly in elderly patients sensitive to CNS effects 7
• Scopolamine may be considered when glycopyrrolate is unavailable, but monitor closely for neuropsychiatric adverse effects 7

Critical Safety Considerations

Absolute Contraindications

• Angle-closure glaucoma 1
• Hypersensitivity to scopolamine, other belladonna alkaloids, or any patch component 1

Warnings and Precautions

• Monitor patients with open-angle glaucoma for increased intraocular pressure; discontinue immediately if signs of acute angle-closure glaucoma develop 1
• Neuropsychiatric effects are significant: the patch may cause psychiatric symptoms, cognitive impairment, seizures, hallucinations (especially in elderly and pediatric patients), confusion, and impaired mental/physical abilities 1, 8
• Avoid use in pregnant women with severe preeclampsia due to risk of eclamptic seizures 1
• Use caution in patients with intestinal obstruction, pyloric obstruction, or impeded urine flow; discontinue if difficulty urinating develops 1
• Withdrawal symptoms may occur 24 hours or more after patch removal, including anticholinergic rebound effects 1

Common Adverse Effects

• Dry mouth occurs in 50-60% of patients, drowsiness in up to 20%, and allergic contact dermatitis in 10% 2
• Visual disturbances are common: blurred vision, mydriasis, and impaired accommodation occur frequently, with hypermetropic individuals at particular risk, especially with repeated applications 1, 8
• Memory impairment for new information and reduced attention may occur, particularly with prolonged or repeated use 8
• Bradycardia, pharyngitis, dizziness, somnolence, agitation, and confusion are reported in ≥3% of PONV patients 1

Application and Handling Instructions

Proper Application Technique

• Apply only one patch at a time to hairless skin behind one ear 1
• Never cut the patch 1
• Wash hands thoroughly with soap and water immediately after application to prevent accidental eye contamination, which can cause cycloplegia and mydriasis 1, 2
• Avoid touching or applying pressure to the patch once applied 1

Removal and Disposal

• Upon removal, fold the used patch in half with sticky sides together and discard safely to prevent accidental contact or ingestion 1
• Wash both hands and the application site with soap and water after removal 1

Managing Skin Irritation

• Remove the patch immediately at first sign of skin irritation 9
• Cleanse the affected area with non-medicated soap and water, then apply low-potency topical corticosteroid 9
• Consider glycopyrrolate (0.2-0.4 mg IV/SC every 4 hours) as first-line alternative if scopolamine must be discontinued 9
• Rotate application sites between ears if continued scopolamine use is necessary 9

Pharmacokinetic Considerations

• Significant interindividual variation exists in plasma concentrations (range 11-240 pg/mL at steady state), with 20-30% of subjects failing to attain protective concentrations, potentially explaining treatment failures 2
• Bioavailability is limited (3-27%) with oral administration due to extensive first-pass metabolism, making the transdermal route preferable for sustained effect 3
• Grapefruit juice significantly increases scopolamine bioavailability by inhibiting intestinal CYP3A, prolonging time to peak concentration and increasing AUC by 42% 3
• The patch releases scopolamine at approximately 5 μg/hour after an initial priming dose of 140 μg 2, 3