Scopolamine

Scopolamine or Hyoscine, formula C₁₇H₂₁ NO₄, which occurs in the roots of certain herbs belonging to the nightshade family. A viscous liquid, it dissolves fairly readily in water. The monohydrate of the alkaloid forms crystals of melting point 59° C (138° F). Scopolamine is optically active and levorotary—that is, it rotates the plane of polarized light to the left. Scopolamine is used medically to dilate the eye; to depress the central nervous system, which effect makes it valuable as a sedative and preanesthetic; and to prevent motion sickness.

Scopolamine's effect on the central nervous system also makes it useful as a “truth serum,” by means of which uncooperative persons may be forced to answer questions. This method of interrogation is common in popular fiction, but cannot be used legally in the United States without consent, and because evidence so obtained is unreliable, it is often inadmissible in court. See Anesthesia.