By Marcello Cherchi, MD PhD
For patients
Scopolamine is a motion sickness medication usually given as a patch attached behind the ear. If you touch the patch and then touch your eyes, it may make your pupil larger or make your vision blurry.
For clinicians
Practical summary
Scopolamine is a parasympatholytic whose anti-emetic properties are useful in otoneurology for the management of constitutional motion sensitivity (motion sickness). It is typically administered in a transdermal patch formulation. Adverse effects include ophthalmologic (mydriasis, impaired accommodation) and cognitive (sedation, amnesia). It is generally considered safe for pregnancy and nursing.
Pharmacology
Scopolamine is an alkaloid that functions as a nonselective antagonist of peripheral and central muscarinic acetylcholine receptors, giving it parasympatholytic properties whose effects include sedation, amnesia, and anti-emetic (Renner et al. 2005).
Adverse effects
Scopolamine’s parasympatholytic effects can have ophthalmological consequences of mydriasis and reduction in the near point of accommodation (Firth and Walker 2006) resulting in symptoms such as photophobia, glare and blurred vision. When scopolamine is systemically administered, both eyes can be affected. However, when patients use the transdermal scopolamine patch, they may inadvertently touch the patch and then touch one eye, causing lateralizing ophthalmological effects (e.g., unilateral mydriasis) (Rosen 1986).
Cautions and contraindications
Frequent or prolonged use of scopolamine increases the risk of withdrawal when the drug is discontinued (Saxena and Saxena 1990).
Scopolamine does cross the placenta, but has not been shown to have any teratogenic effects, so it is generally classified as safe to take during pregnancy and nursing (Renner et al. 2005).
Relevance in otoneurology
Scopolamine is sometimes used to control postoperative nausea. In otoneurology and general medicine the most common use of scopolamine is to manage constitutional motion sensitivity (motion sickness) (Spinks et al. 2007).
Other notes
Scopolamine is available in oral formulation, but is more commonly administered via a transdermal patch (Nachum et al. 2006). Advantages of the patch include that the effects of the drug can be aborted, if necessary, simply by removing the patch.
References
Firth AY, Walker K (2006) Visual side-effects from transdermal scopolamine (hyoscine). Dev Med Child Neurol 48: 137-8. doi: 10.1017/s0012162206000296
Nachum Z, Shupak A, Gordon CR (2006) Transdermal Scopolamine for Prevention of Motion Sickness. Clinical Pharmacokinetics 45: 543-566. doi: 10.2165/00003088-200645060-00001
Renner UD, Oertel R, Kirch W (2005) Pharmacokinetics and pharmacodynamics in clinical use of scopolamine. Ther Drug Monit 27: 655-65. doi: 10.1097/01.ftd.0000168293.48226.57
Rosen NB (1986) Accidental mydriasis from scopolamine patches. J Am Optom Assoc 57: 541-2.
Saxena K, Saxena S (1990) Scopolamine withdrawal syndrome. Postgrad Med 87: 63-6. doi: 10.1080/00325481.1990.11704520
Spinks AB, Wasiak J, Villanueva EV, Bernath V (2007) Scopolamine (hyoscine) for preventing and treating motion sickness. Cochrane Database Syst Rev: Cd002851. doi: 10.1002/14651858.CD002851.pub3
