(1989; 60 pages) [French]
Group: anticholinergic agent
Tablet: 1 mg (sulfate)
Injection: 1 mg (sulfate) in 1-ml ampoule
Atropine is an alkaloid of Atropa belladonna that competitively antagonizes the muscarinic action of acetylcholine and other cholinergic drugs.
Atropine is readily absorbed from the gastrointestinal tract. Its half-life in plasma ranges from 2 to 3 hours. It is largely metabolized in the liver and excreted in the urine.
In general surgery:
• to inhibit salivary and bronchial secretions particularly during ether or ketamine anaesthesia (preoperative medication)
• to inhibit cardiac dysrhythmias, bradycardia and hypotension resulting from excessive vagal stimulation
• to block the parasympathomimetic effects of anticholinesterase agents used to restore muscular activity on completion of surgery.
Dosage and administration
Adults: 20 micrograms/kg i.m. 30-60 minutes before induction, or up to a maximum of 500 micrograms i.v. immediately before induction.
Children: 20 micrograms/kg i.m. 30-60 minutes before induction, or the same dose orally 2 hours before induction.
Inhibition of cardiac dysrhythmias
Adults: 400-1000 micrograms i.v.
Children: 10-30 micrograms/kg i.v.
Restoration of muscular activity
Adults: 600-1200 micrograms i.v. 2-3 minutes before administration of the anticholinesterase agent.
Children: 20 micrograms/kg administered as above.
Atropine should be used at reduced dosage in the elderly and in patients with cardiovascular insufficiency, hyperthyroidism, hypertension or hepatic or renal insufficiency.
Use in pregnancy
Atropine should be used during pregnancy only when the need outweighs any possible risk to the fetus.
Signs of parasympathetic blockade commonly occur within the therapeutic dosage range. These include dry mouth, blurred vision, raised ocular tension, flushing and dryness of skin, skin rashes and difficulty in micturition, which occasionally results in urinary retention.
Less common are atrial dysrhythmias, ventricular tachycardia or fibrillation and confusional states.
Heat prostration and convulsions can occur, especially in febrile children. This risk is intensified in a hot, humid environment.
Serious overdosage is characterized by signs of parasympathetic blockade, central excitation, skin rash and hyperpyrexia. Hallucinations, mania and delirium may be followed by convulsions. Circulatory and respiratory collapse are terminal events.
Treatment consists of symptomatic and supportive therapy. Activated charcoal should be administered followed by gastric aspiration. Neostigmine (250 micro-grams subcutaneously) will reverse the peripheral but not the central effects of atropine. Small doses of diazepam may help delay excitation. Fever may be reduced by sponging with tepid water. Mechanically assisted respiration may be required.
Atropine injection and tablets should be stored in hermetically closed containers protected from light, and should not be allowed to freeze.