Atropine is a medication used to treat certain types of nerve agent and pesticide poisonings, 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 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 poisonings.
Common side effects include a dry mouth, large pupils, urinary retention, constipation, and a fast heart rate. It should generally not be used in people with glaucoma. While there is no evidence that its use during pregnancy causes birth defects, it has not been well studied. It is likely safe during breastfeeding. It is an antimuscarinic (also known as an anticholinergic) that works by inhibiting the parasympathetic nervous system.
Atropine occurs naturally in a number of plants of the nightshade family including deadly nightshade, Jimson weed, and mandrake. It was first isolated in 1833. Atropine is on the WHO Model List of Essential Medicines, the most important medications needed in a basic health system. It is available as a generic medication and not very expensive. A one-milligram vial costs wholesale between 0.06 and 0.44 USD.
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.
Atropine eye drops have been shown to be effective in slowing the progression of myopia in children in several studies, but it is not available for this use, and side effects would limit its use.
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, may repeat every 3 to 5 minutes up to a total dose of 3 mg (maximum 0.04 mg/kg).
Atropine is also useful in treating second-degree heart block Mobitz Type 1 (Wenckebach block), and also third-degree heart block with a high Purkinje or AV-nodalescape rhythm. It is usually not effective in second-degree heart block Mobitz type 2, and in third-degree heart block with a low Purkinje or ventricular escape rhythm.
Atropine's actions on the parasympathetic nervous system inhibit salivary and mucus glands. The drug may also inhibit sweating via the sympathetic nervous system. This can be useful in treating hyperhidrosis, and can prevent the death rattle of dying patients. Even though atropine has not been officially indicated for either of these purposes by the FDA, it has been used by physicians for these purposes.
Atropine is not an actual antidote for organophosphate poisoning. However, by blocking the action of acetylcholine at muscarinic receptors, atropine also serves as a treatment for poisoning by organophosphateinsecticides and nerve gases, such as tabun (GA), sarin (GB), soman (GD) and VX. Troops who are likely to be attacked with chemical weapons often carry autoinjectors with atropine and obidoxime, for rapid injection into the muscles of the thigh. Atropine is often used in conjunction with pralidoxime chloride.
Atropine is given as a treatment for SLUDGE syndrome (salivation, lacrimation, urination, diaphoresis, gastrointestinal motility, emesis) symptoms caused by organophosphate poisoning. Another mnemonic is DUMBBELSS, which stands for diarrhea, urination, miosis, bradycardia, bronchoconstriction, excitation (as of muscle in the form of fasciculations and CNS), lacrimation, salivation, and sweating (only sympathetic innervation using muscarinic receptors).
Some of the nerve agents attack and destroy acetylcholinesterase by phosphorylation, so the action of acetylcholine becomes prolonged. Pralidoxime (2-PAM) is the cure for organophosphate poisoning because it can cleave this phosphorylation. Atropine can be used to reduce the effect of the poisoning by blocking muscarinic acetylcholine receptors, which would otherwise be overstimulated, by excessive acetylcholine accumulation.
Adverse reactions to atropine include ventricular fibrillation, supraventricular or ventricular tachycardia, dizziness, nausea, blurred vision, loss of balance, dilated pupils, photophobia, dry mouth and potentially extreme confusion, dissociative hallucinations and excitation especially amongst the elderly. Most of available ampules are carried on sulphate which can cause histamine release and anaphylaxis to susceptible patients or patients with allergy to sulpha products.These latter effects are because atropine is able to cross the blood–brain barrier. Because of the hallucinogenic properties, some have used the drug recreationally, though this is potentially dangerous and often unpleasant.
In overdoses, atropine is poisonous. Atropine is sometimes added to potentially addictive drugs, particularly anti-diarrhea opioid drugs such as diphenoxylate or difenoxin, wherein the secretion-reducing effects of the atropine can also aid the anti-diarrhea effects.
Although atropine treats bradycardia (slow heart rate) in emergency settings, it can cause paradoxical heart rate slowing when given at very low doses (i.e.