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. Atropine or diphenhydramine can be used to treat muscarine intoxication. Irinotecan induced diarrhea
Atropine has been observed to prevent or treat irinotecan induced acute diarrhea. Side effects
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, deliriant hallucinations, and excitation especially among the elderly. 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 antidiarrhea opioid drugs such as diphenoxylate or difenoxin, wherein the secretion-reducing effects of the atropine can also aid the antidiarrhea 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. <0.5 mg), presumably as a result of central action in the CNS. One proposed mechanism for atropines paradoxical bradycardia effect at low doses involves blockade of inhibitory presynaptic muscarinic autoreceptors, thereby blocking a system that inhibits the parasympathetic response.Atropine is incapacitating at doses of 10 to 20 mg per person. Its LD50 is estimated to be 453 mg per person (by mouth) with a probit slope of 1.8.
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. Heart
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, 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-nodal escape rhythm.