Hyoscine

Hyoscine, also known as scopolamine, is a tropane alkaloid drug that acts as a competitive antagonist at muscarinic acetylcholine receptors. It is primarily used to prevent and treat motion sickness, nausea, and vomiting. The compound is naturally found in plants of the nightshade family, particularly in species such as Datura stramonium and Hyoscyamus niger, from which it derives its name.

The medication works by blocking the action of acetylcholine in the central nervous system and peripheral tissues, particularly affecting the vestibular system responsible for balance and spatial orientation. This mechanism helps reduce the conflicting signals that trigger motion sickness symptoms. Hyoscine is available in several formulations including transdermal patches, tablets, and injectable solutions.

When applied as a transdermal patch behind the ear, hyoscine provides sustained release over several days, making it particularly effective for extended travel. Oral tablets are typically taken 30 minutes before travel, while injectable forms are used in medical settings for severe nausea and vomiting. Common side effects include dry mouth, drowsiness, blurred vision, and constipation. The drug can impair cognitive function and reaction time, so patients are advised to avoid driving or operating machinery while taking it.

Hyoscine is contraindicated in certain medical conditions including glaucoma, urinary retention, and severe liver disease. It may interact with other medications that affect the central nervous system. The drug has also been studied for its potential use in treating depression and as a research tool in neuroscience due to its effects on memory and cognition.

First isolated in the 1880s, hyoscine has remained an important medication in travel medicine and anesthesia. Its effectiveness in preventing motion sickness has made it a popular choice among travelers, though its sedating effects limit its use in situations requiring alertness.