Atropine

Atropine is a prescription drug that can be administered in several ways. It is in a class of drugs called anticholinergics, which blocks the receptors of the neurotransmitter, or nerve messenger, known as acetylcholine. Doctors use atropine to manage the symptoms of conditions such as Parkinson’s disease, treat some heart conditions (such as bradycardia) and some gastrointestinal disorders, and manage certain poisonings as an antidote.

Overview

Experts generally credit German pharmacist Heinrich Mein with isolating atropine in pure form in 1831. Atropine is a natural alkaloid. Alkaloids are nitrogen-containing plant compounds that can have significant physical effects on people and animals. Many plants containing alkaloids are poisonous, including Atropa belladonna, which produces atropine and provides its name. Belladonna is in the nightshade family, a category that includes many plants and plant parts that are poisonous to varying degrees.

Another German chemist Richard Willstätter first synthesized a derivative of atropine known as tropinone in 1901. Beginning in 1910, atropine was given to patients before surgery. One of the effects of atropine is that it helps to dry up mucus and other secretions in the nose, mouth, throat, lungs, and stomach. The anesthesia used to put patients to sleep during surgery prevents them from being able to swallow and slows other actions of the body. During surgery, mucus would build up in the mouth, presenting a choking hazard. Physicians used atropine to counteract this problem. In updated resuscitation guidance issued in 2025, routine or indiscriminate use of atropine before critical care intubation is not recommended, and its role in this setting remains controversial.

Scientists have found many other uses for atropine over the years. Doctors still sometimes use it as a pre-surgical treatment to help dry mucosal secretions. However, physicians in the twenty-first century use other agents more often. It is still used in some settings to treat bradycardia. For these purposes, doctors usually administer atropine by injection.

Some medications used for allergic rhinitis have atropine-like (anticholinergic) effects that reduce nasal secretions. It has also historically been used in medications intended to help with symptoms of gastrointestinal distress in conditions such as diarrhea, diverticulitis, infant colic, and irritable bowel syndrome, although in most cases the significant risk of side effects does not make this a standard treatment option. In these cases, it works by either reducing stomach acid or calming spasms in the digestive system.

In addition to the oral and injectable forms, atropine is also formulated into eye drops. These can be used to dilate the eye or widen the pupil, before eye exams, and to treat some eye conditions, including uveitis, which is a form of eye inflammation. Homatropine is often used in eye drops to dilate the eye because it is less powerful than atropine and its effects do not last as long, reducing the amount of time the patient needs to protect the eye from light. Low-dose atropine (particularly concentrations between 0.01% and 0.05%) continues to be studied and increasingly prescribed in some countries for slowing myopia progression in children.

Doctors sometimes use atropine off-label to manage specific neurological symptoms in some patients with brain cancer. It is also used to counteract poisoning caused by some mushrooms, certain types of insecticides, and nerve gases. Atropine has many off-label uses as well. This means that doctors prescribe the drug for uses that regulatory agencies have not officially approved. However, physicians often prescribe the drug because they believe there is evidence that it can help the patient anyway.

Bibliography

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