Brands, Medical Use, Clinical Data
- Adjuvants, Anesthesia
- Anti-Arrhythmia Agents
- Bronchodilator Agents
- Muscarinic Antagonists
Brands / Synonyms
Atnaa; Atropair; Atropen; Atropen Auto-Injector; Atropin; Atropin [German]; Atropin-flexiolen; Atropina; Atropina [Italian]; Atropine; Atropine Care; Atropine Sulfate; Atropine Sulfate Ansyr Plastic Syringe; Atropine Sulfate S.O.P.; Atropinol; Atropisol; Atrosulf; Diphenoxylate and Atropine; DL-Hyoscyamine; DL-Tropyl tropate; Duodote; Enlon Plus; Enlon-Plus; Equipin; Eyesules; Homapin-10; Homapin-5; Hyoscyamine; I-Tropine; Isopto Atropine; Isopto-atropine; Lomotil; Minims Atropine; Motofen; Ocu-Tropine; PB Hyos; Protamine + Atropine; Protamine and Atropine; Tropic acid, ester with tropine; Tropine tropate; Troyl tropate
For the treatment of poisoning by susceptible organophosphorous nerve agents having cholinesterase activity as well as organophosphorous or carbamate insecticides.
Atropine, a naturally occurring belladonna alkaloid, is a racemic mixture of equal parts of d- and l-hyoscyamine, whose activity is due almost entirely to the levo isomer of the drug. Atropine is commonly classified as an anticholinergic or antiparasympathetic (parasympatholytic) drug. More precisely, however, it is termed an antimuscarinic agent since it antagonizes the muscarine-like actions of acetylcholine and other choline esters. 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 may also lessen the degree of partial heart block when vagal activity is an etiologic factor. Atropine 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.
Mechanism of Action
Generally, atropine lowers the "rest and digest" activity of all muscles and glands regulated by the parasympathetic nervous system. This occurs because atropine is a competitive inhibitor of the muscarinic acetylcholine receptors (acetylcholine is the neurotransmitter used by the parasympathetic nervous system).
Atropine is rapidly and well absorbed after intramuscular administration. Atropine disappears rapidly from the blood and is distributed throughout the various body tissues and fluids.
Oral, mouse: LD50 = 75 mg/kg. Symptoms of overdose includes widespread paralysis of parasympathetically innervated organs. Dry mucous membranes, widely dilated and nonresponsive pupils, tachycardia, fever and cutaneous flush are especially prominent, as are mental and neurological symptoms. In instances of severe intoxication, respiratory depression, coma, circulatory collapse and death may occur.
Biotrnasformation / Drug Metabolism
Much of the drug is destroyed by enzymatic hydrolysis, particularly in the liver. From 13 to 50% is excreted unchanged in the urine.
In the face of life-threatening poisoning by organophosphorous nerve agents and insecticides, there are
no absolute contraindications for the use of atropine.
When atropine and pralidoxime are used together, the signs of atropinization (flushing, mydriasis,
tachycardia, dryness of the mouth and nose) may occur earlier than might be expected than when atropine is used alone
because pralidoxime may potentiate the effect of atropine.
The following precautions should be kept in mind in the treatment of anticholinesterase poisoning
although they do not bear directly on the use of atropine and pralidoxime. Since barbiturates are potentiated by the
anticholinesterases, they should be used cautiously in the treatment of convulsions.