pilocarpine, naturally occurring alkaloid obtained from plants of the genus Pilocarpus (family Rutaceae). By mimicking the effects of acetylcholine, pilocarpine acts as a stimulant of the parasympathetic nervous system. It promotes the flow of saliva and urine and increases perspiration. Because it increases the outflow of fluid from the eye, reduces the pressure within the eye, and causes the pupil to contract, the drug is used to treat some types of glaucoma. It is also used for some tongue disorders.