Adult: In mild poisoning: Initially, 1-2 mg via IV inj every 5-60 minutes followed by subsequent 2 mg dose via IV/IM inj every 5-60 minutes until muscarinic signs and symptoms subside. In moderate-severe poisoning: Initially, 2-6 mg via IV inj followed by subsequent 2-6 mg dose via IV/IM inj every 5-60 minutes until muscarinic signs and symptoms subside. Max: 50 mg in 1st 24 hours. Child: Infants and children: Initially, 0.05-0.1 mg/kg via IV/IM inj every 5-10 minutes repeated until muscarinic signs and symptoms subside.
Adult: Initially, 0.5 mg repeated every 3-5 minutes. Max total: 3 mg. Child: Initially, 0.02 mg/kg per dose. May repeat once every 5 minutes. Max: 0.5 mg/dose.
Ophthalmic Mydriasis and cycloplegia for refraction
Adult: As 1% solution: Instill 1-2 drop(s) in the conjunctiva 40 minutes to 1 hour prior to procedure. May be repeated bid as necessary. As 1% ointment: Apply 0.3-0.5 cm into the conjunctival sac up to 3 times daily. Child: As 1% solution: Instill 1 drop into each eye bid for 1-3 days prior to procedure. As 1% ointment: Apply 0.3 cm into the conjunctival sac up to thrice daily for 1-3 days before the procedure.
Ophthalmic Iritis, Uveitis
Adult: As 1% solution: Instill 1-2 drop(s) into the eye up to 4 times daily. Child: As 1% solution: Instill 1 drop into each eye up to 3 times daily.
Adult: 0.3-0.6 mg via IM/SC inj 30-60 minutes prior to anaesthesia induction. Alternatively, 0.3-0.6 mg via IV inj immediately before anaesthesia induction. Child: <3 kg: 0.1 mg; 7-9 kg: 0.2 mg; 12-16 kg: 0.3 mg; >20 kg: 0.4-0.6 mg. All doses to be given via IM/SC inj administered 30-60 minutes before anaesthesia.
May be taken with or without food.
IV/IM/SC: Incompatible with hydroxybenzoate preservatives, bromides, iodides, alkalis, noradrenaline bitartrate, metaraminol bitartrate, Na bicarbonate, methohexital Na ampicillin Na, nitrofurantoin, thiopentone Na, vitamin B complex with ascorbic acid, warfarin Na and heparin Na.
Angle-closure glaucoma, narrow angle between the iris and cornea, 2nd or 3rd degree AV block, achalasia of oesophagus, paralytic ileus, severe ulcerative colitis, intestinal atony, toxic megacolon, pyloric stenosis, prostatic hypertrophy, obstructive uropathy, myasthenia gravis. Lactation (IV).
Patients with Down’s syndrome, brain damage, autonomic neuropathy, increased intraocular pressure, spastic paralysis, hiatal hernia, hyperthyroidism, gastric ulcers, GERD, diarrhoea, COPD, heart failure, myocardial ischaemia, hypertension, and cardiac surgery. Patients with fever or those exposed to high ambient temperature. Hepatic and renal impairment. Children. Pregnancy and lactation.
Significant: Tachycardia, transient bradycardia, pulmonary oedema, urinary retention, delirium, agitation, amnesia; photophobia, blurred vision (ophthalmic). Rarely, hypertensive crisis and seizures. Cardiac disorders: Palpitations, chest pain. Eye disorders: Decreased lacrimation. Gastrointestinal disorders: Dry mouth, dysphagia, constipation, nausea, vomiting. General disorders and admin site conditions: Fever, irritability, asthenia, ataxia. Investigations: Irregular pulse, increased intraocular pressure, abnormal EEG, ECG changes. Metabolism and nutrition disorders: Increased thirst, hypokalaemia, hyperglycaemia. Nervous system disorders: Dysgeusia, restlessness, dizziness, headache. Psychiatric disorders: Confusion, hallucination, disorientation, insomnia. Renal and urinary disorders: Difficulty in micturition, urinary urgency. Respiratory, thoracic and mediastinal disorders: Dyspnoea, reduced bronchial secretion, laryngitis. Skin and subcutaneous tissue disorders: Anhidrosis, hot and dry skin, rash, dermatitis. Vascular disorders: Flushing. Potentially Fatal: Asystole, MI, atrioventricular arrhythmia, atrial fibrillation, AV dissociation, ventricular tachycardia, respiratory depression, coma. Rarely, angioedema.
This drug may cause confusion, dizziness or blurred vision, if affected, do not drive or operate machinery.
Monitor blood pressure, pulse rate, heart rate, and ECG. Check for signs and symptoms of atropine toxicity (e.g. fever, muscle fasciculations, delirium, and mental status).
Symptoms: Hyperthermia, hypertension, increased respiratory rate, tachycardia, dry mouth, nose or throat; dilated pupils, blurred vision, dizziness, drowsiness, nausea and vomiting. CNS stimulation characterised by restlessness, confusion, excitement, ataxia, incoordination, psychotic reactions, delirium, seizures. Severe intoxication may lead to CNS depression, coma, respiratory failure and death. Management: Symptomatic and supportive treatment. Administer fluid replacement and standard treatment for shock. Correct hypoxia, hypotension and metabolic acidosis with IV Na bicarbonate. Reduce body temperature using cold packs or mechanical cooling devices. Control excitement by administering diazepam or short-acting barbiturate. Urine catheterisation may help avoid urinary retention. Give activated charcoal for oral overdose. Reserve IV physostigmine for patients with extreme delirium or agitation, repetitive seizures, severe sinus tachycardia, supraventricular tachycardia and unresponsive hyperthermia. Administer IV propranolol as alternative treatment for conditions contraindicated to physostigmine (e.g. asthma, gangrene, cardiac conduction defect, ventricular tachyarrhythmia, gastrointestinal and urinary obstruction).
Additive antimuscarinic effect with amantadine, antiarrhythmics (e.g. disopyramide, quinidine), anticholinergics, TCA, MAOIs, antipsychotics (e.g. phenothiazine, clozapine, haloperidol), antiparkinsonian drugs, antispasmodics (e.g. domperidone), and some antihistamines (e.g. promethazine). Reduces absorption of ketoconazole and mexiletine. Antagonises therapeutic effects of synthetic choline esters (e.g. bethanechol, carbachol), anticholinesterase drugs (e.g. physostigmine, neostigmine, pyridostigmine), and cholinomimetic alkaloids (e.g. pilocarpine). May increase risk of severe constipation with opioid analgesics. Antagonises miotic actions of ophthalmic long-acting cholinergic antiglaucoma agents (e.g. echothiopate). May increase toxic effects of antimyasthenics, K citrate, K supplements. May antagonise gastrointestinal motility effects of cisapride, domperidone and metoclopramide.
Alcohol may markedly impair attention.
Description: Mechanism of Action: Atropine is an anticholinergic agent which competitively blocks the binding of acetylcholine to muscarinic receptors at the parasympathetic sites in the CNS and peripheral tissues such as the heart, intestines, bronchial muscles, iris and secretory glands. Atropine abolishes bradycardia by diminishing vagal activity thereby increasing heart rate. It promotes bronchodilation by inhibiting secretions in the respiratory tract and relaxing the bronchial smooth muscles. Topical atropine onto the eyes induces mydriasis and cycloplegia by inhibiting circular pupillary sphincter muscle contraction and paralysing the ciliary muscles responsible for accommodation respectively. Onset: Ophthalmic: Within minutes. Increased heart rate: 2-4 minutes (IV); Approx 15-30 minutes (IM). Inhibition of salivation: Approx 30 minutes (IM). Duration: Inhibition of salivation: ≤4 hours (IM). Mydriasis: 7-12 days (ophthalmic). Cycloplegia: >14 days (ophthalmic). Pharmacokinetics: Absorption: Rapidly absorbed from the gastrointestinal tract. Well absorbed from mucous membranes, eyes, and through intact skin. Bioavailability: Approx 90% (oral); Approx 19-95% (ophthalmic). Time to peak plasma concentration: Approx 1 hour (oral); approx 2-4 minutes (IV); approx 30 minutes (IM); 3 minutes (IM autoinjector); approx 3-60 minutes (ophthalmic). Distribution: Widely distributed throughout the body. Crosses placenta and enters breast milk in small quantities. Crosses the blood-brain barrier. Volume of distribution: Approx 2-4 L/kg. Plasma protein binding: 14-44% mainly to serum albumin. Metabolism: Incompletely metabolised in the liver via enzymatic hydrolysis to several metabolites such as tropic acid, tropine, and glucuronide conjugates. Excretion: Via urine (13-50% as unchanged drug; 33% as metabolites). Elimination half-life: Approx 2-5 hours.
Tab/IV/IM/SC/Ophthalmic ointment: Store between 15-30°C. Do not freeze. Ophthalmic solution: Store between 2-25°C. Protect from light.
A03BA01 - atropine ; Belongs to the class of belladonna alkaloids, tertiary amines. Used in the treatment of functional gastrointestinal disorders. S01FA01 - atropine ; Belongs to the class of anticholinergics used as mydriatics and cycloplegics.
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