What is the recommended dosage and usage of hyoscyamine (scopolamine) for motion sickness and gastrointestinal disorders?

From the Guidelines

For motion sickness, scopolamine is typically used as a transdermal patch with a dosage of 1.5 mg applied behind the ear 4 hours before travel, providing protection for up to 72 hours, as indicated in the study 1. When considering the treatment of motion sickness and gastrointestinal disorders, it's crucial to differentiate between hyoscyamine and scopolamine, as they are often confused due to their classification as anticholinergics.

• For motion sickness, the transdermal patch formulation of scopolamine is preferred due to its prolonged action and convenience, with the standard adult dosage being one 1.5 mg patch, applied as mentioned, to prevent motion sickness for up to 3 days 1.
• For gastrointestinal disorders, hyoscyamine is commonly prescribed, with dosages ranging from 0.125-0.25 mg taken orally every 4 hours as needed, not exceeding a maximum daily dose of 1.5 mg, as this can help manage symptoms without significantly increasing the risk of side effects. Key considerations include the potential side effects such as dry mouth, blurred vision, and urinary retention, and the necessity to avoid these medications in patients with glaucoma, urinary retention, severe ulcerative colitis, myasthenia gravis, or intestinal obstruction, emphasizing the importance of careful patient selection and monitoring 1. Given the information from the study 1, it's clear that while scopolamine has a defined role in motion sickness prevention, its use in gastrointestinal disorders is off-label and not as well-supported by clinical evidence, highlighting the need for careful consideration of treatment options based on the latest clinical guidelines and patient-specific factors.

From the FDA Drug Label

DOSAGE AND ADMINISTRATION HYOSYNE ORAL DROPS (Hyoscyamine Sulfate Oral Solution) Dosage may be adjusted according to the conditions and severity of symptoms. Measuredosage very carefully. Adults and pediatric patients 12 years of age and older: 1 to 2 mL every four hours or as needed. Do not exceed 12 mL in 24 hours Pediatric patients 2 to under 12 years of age: 1/4 to 1 mL every four hours or as needed. Do not exceed 6 mL in 24 hours.

The recommended dosage and usage of hyoscyamine for gastrointestinal disorders is:

• Adults and pediatric patients 12 years of age and older: 1 to 2 mL every four hours or as needed, not exceeding 12 mL in 24 hours.
• Pediatric patients 2 to under 12 years of age: 1/4 to 1 mL every four hours or as needed, not exceeding 6 mL in 24 hours. However, there is no information provided for the usage of hyoscyamine for motion sickness in the given drug label. 2

From the Research

Recommended Dosage and Usage of Hyoscyamine (Scopolamine)

The recommended dosage and usage of hyoscyamine (scopolamine) for motion sickness and gastrointestinal disorders are as follows:

• For motion sickness, a single transdermal therapeutic system (TTS) patch containing 1.5 mg of scopolamine can be applied to the postauricular area at least 6-8 hours before the anti-motion sickness effect is required 3.
• The patch releases 0.5 mg of scopolamine over a period of 3 days, with a steady-state concentration achieved after 8-12 hours 3.
• For faster protection, the patch can be applied 1 hour before the journey in combination with oral scopolamine (0.3 or 0.6 mg) 3.
• After 72 hours, the patch should be removed and a new one applied behind the opposite ear 3.
• The recommended oral dose for adults is one to two tablets of scopolamine hydrobromide 0.3 mg as a single dose, repeated four to six hours later if required, with a maximum dose of four tablets over a 24-hour period 4.

Pharmacokinetics and Pharmacodynamics

The pharmacokinetics and pharmacodynamics of scopolamine depend on the dosage form, with the transdermal patch providing a constant release of the drug and minimizing adverse effects 5, 3.

• The protective plasma concentration of scopolamine is estimated to be 50 pg/mL, which is achieved after 6 hours with the TTS patch 3.
• The steady-state concentration of scopolamine is approximately 100 pg/mL, which is achieved after 8-12 hours with the TTS patch 3.
• Scopolamine has a limited bioavailability if orally administered, with a maximum drug concentration occurring approximately 0.5 hours after oral administration 5.

Adverse Effects

The adverse effects of scopolamine include:

• Dry mouth, which occurs in about 50-60% of subjects 3.
• Drowsiness, which occurs in up to 20% of subjects 3.
• Allergic contact dermatitis, which occurs in 10% of subjects 3.
• Transient impairment of ocular accommodation, which can be caused by finger-to-eye contamination 3.
• Anticholinergic syndrome, which can occur with unintentional overdose of scopolamine 4.