Atropine

Atropine is a tropane alkaloid and anticholinergic medication used to treat certain types of nerve agent and pesticide poisonings as well as some types of slow heart rate, and to decrease saliva production during surgery. It is typically given intravenously or by injection into a muscle. Eye drops are also available which are used to treat uveitis and early amblyopia. The intravenous solution usually begins working within a minute and lasts half an hour to an hour. Large doses may be required to treat some poisonings.

Common side effects include dry mouth, abnormally large pupils, urinary retention, constipation, and a fast heart rate. It should generally not be used in people with closed-angle glaucoma. While there is no evidence that its use during pregnancy causes birth defects, this has not been well studied so sound clinical judgment should be used. It is likely safe during breastfeeding. It is an antimuscarinic (a type of anticholinergic) that works by inhibiting the parasympathetic nervous system.

Atropine occurs naturally in a number of plants of the nightshade family, including deadly nightshade (Atropa belladonna), jimsonweed (Datura stramonium), mandrake (Mandragora officinarum) and angel's trumpet (Brugmansia). Atropine was first isolated in 1833. It is on the World Health Organization's List of Essential Medicines. It is available as a generic medication.

Topical atropine is used as a cycloplegic, to temporarily paralyze the accommodation reflex, and as a mydriatic, to dilate the pupils. Atropine degrades slowly, typically wearing off in 7 to 14 days, so it is generally used as a therapeutic mydriatic, whereas tropicamide (a shorter-acting cholinergic antagonist) or phenylephrine (an α-adrenergic agonist) is preferred as an aid to ophthalmic examination.

In refractive and accommodative amblyopia, when occlusion is not appropriate sometimes atropine is given to induce blur in the good eye. Evidence suggests that atropine penalization is just as effective as occlusion in improving visual acuity.

Antimuscarinic topical medication is effective in slowing myopia progression in children; accommodation difficulties and papillae and follicles are possible side effects. All doses of atropine appear similarly effective, while higher doses have greater side effects. The lower dose of 0.01% is thus generally recommended due to fewer side effects and potential less rebound worsening when the atropine is stopped.

Injections of atropine are used in the treatment of symptomatic or unstable bradycardia.

Atropine was previously included in international resuscitation guidelines for use in cardiac arrest associated with asystole and PEA but was removed from these guidelines in 2010 due to a lack of evidence for its effectiveness. For symptomatic bradycardia, the usual dosage is 0.5 to 1 mg IV push; this may be repeated every 3 to 5 minutes, up to a total dose of 3 mg (maximum 0.04 mg/kg).