Atropine is an alkaloid (naturally occurring amine produced by a plant) extracted from the deadly nightshade (Atropa belladonna) and other plants of the nightshade family (Figure 1). It can also be chemically synthesized by the reaction of tropine with tropic acid in the presence of hydrochloric acid.

Figure 1.Atropa belladonaflowers (left) and berries (right).

Atropine is a muscarinic receptor blocker in the autonomic nervous system. This means that it preventsacetylcholinefrom binding to and activating the receptor and therefore it reduces the muscle contraction.