scopolamine, alkaloid drug obtained from a number of plants of the family Solenaceae, including nightshade, henbane, and jimsonweed. Scopolamine is an effective remedy for motion sickness, probably because of its ability to depress the central nervous system (brain and spinal cord). Like atropine, it has a depressant action on parasympathetic nerves and in larger doses on autonomic ganglia. Scopolamine is also used to dry up secretions and dilate the bronchi during anesthesia and to dilate the pupil during ophthalmological procedures. The drug is the most pharmacologically active of several alkaloid substances found in belladonna, partly because of its greater solubility, which permits more rapid passage to the site of action.