Atropine is the active principle of belladonna, the juice of the deadly nightshade. Because of its action in dilating the pupils, it was at one time used as a cosmetic to give the eyes a full, lustrous appearance. Atropine acts by antagonising the action of the PARASYMPATHETIC NERVOUS SYSTEM. It temporarily impairs vision by paralysing accommodative power (see ACCOMMODATION). It inhibits the action of some of the nerves in the AUTONOMIC NERVOUS SYSTEM. The drug relaxes smooth muscle. It has the eﬀect of checking the activity of almost all the glands of the body, including the sweat glands of the SKIN and the SALIVARY GLANDS in the mouth. It relieves spasm by paralysing nerves in the muscle of the intestine, bile ducts, bladder, stomach, etc. It has the power, in moderate doses, of markedly increasing the rate of the heartbeat, though by very large doses the heart, along with all other muscles, is paralysed and stopped.
Uses In eye troubles, atropine drops are used to dilate the pupil for more thorough examination of the interior of the eye, or to draw the iris away from wounds and ulcers on the centre of the eye. They also soothe the pain caused by light falling on an inﬂamed eye, and are further used to paralyse the ciliary muscle and so prevent accommodative changes in the eye while the eye is being examined with the OPHTHALMOSCOPE. Given by injection, atropine is used before general ANAESTHESIA to reduce secretions in the bronchial tree. The drug can also be used to accelerate the heart rate in BRADYCARDIA as a result of coronary thrombosis.