atory rate and (sometimes) increased depth of respiration produced by Atropine are more probably the result of bronchiolar dilatation. Accordingly, Atropine is an unreliable respiratory stimulant and large or repeated doses may depress respiration.
Adequate doses of Atropine abolish various types of reflex vagal cardiac slowing or asystole. The drug also prevents or abolishes bradycardia or asystole produced by injection of choline esters, anticholinesterase agents or other parasympathomimetic drugs, and cardiac arrest produced by stimulation of the vagus. Atropine also may lessen the degree of partial heart block when vagal activity is an etiologic factor. In some patients with complete heart block, the idioventricular rate may be accelerated by Atropine; in others, the rate is stabilized. Occasionally a large dose may cause atrioventricular (A-V) block and nodal rhythm.
Atropine Sulfate Injection, USP in clinical doses counteracts the peripheral dilatation and abrupt decrease in blood pressure produced by choline esters. However, when given by itself, Atropine does not exert a striking or uniform effect on blood vessels or blood pressure. Systemic doses slightly raise systolic and lower diastolic pressures and can produce significant postural hypotension. Such doses also slightly increase cardiac output and decrease central venous pressure. Occasionally, therapeutic doses dilate cutaneous blood vessels, particularly in the “blush” area (Atropine flush), and may cause Atropine “fever” due to suppression of sweat gland activity in infants and small children.
Atropine disappears rapidly from the blood following injection and is distributed throughout the body. Much of the drug is destroyed by enzymatic hydrolysis, particularly in the liver; from 13 to 50% is excreted unchanged in the urine. Traces are found in various secretions, including milk. Atropine readily crosses the placental barrier and enters the fetal circulation.
Sodium chloride added to render the solution isotonic for injection of the active ingredient is present in amounts insufficient to affect serum electrolyte balance of sodium (Na+) and chloride (Cl¯) ions.
Indications and Usage for Atropine
Atropine Sulfate Injection, USP is indicated (1) as an antisialogogue for preanesthetic medication to prevent or reduce secretions of the respiratory tract, (2) to restore cardiac rate and arterial pressure during anesthesia when vagal stimulation produced by intra-abdominal surgical traction causes a sudden decrease in pulse rate and cardiac action, (3) to lessen the degree of atrioventricular (A-V) heart block when increased vagal tone is a major factor in the conduction defect as in some cases due to digitalis, (4) to overcome severe bradycardia and syncope due to a hyperactive carotid sinus reflex, (5) as an antidote (with external cardiac massage) for cardiovascular collapse from the injudicious use of a choline ester (cholinergic) drug, (6) in the treatment of anticholinesterase poisoning from organophosphorus insecticides, and (7) as an antidote for the “rapid” type of mushroom poisoning due to the presence of the alkaloid, muscarine, in certain species of fungus such as Amanita muscaria.
Contraindications
Atropine generally is contraindicated in patients with glaucoma, pyloric stenosis or prostatic hypertrophy, except in doses ordinarily used for preanesthetic medication.
Warnings
Atropine is a highly potent drug a |
