Atropine Injection

Information from Drugs.com, provided by Covetrus:

Atropine sulfate Injection Caution

Federal law restricts this drug to use by or on the order of a licensed veterinarian.

For intravenous, intramuscular, or subcutaneous use

Dosage and Administration

Dogs and cats: Inject 1 mL for each 20 lbs of body weight as a pre-anesthetic adjuvant or to reduce salivation, bronchial secretion or internal peristalsis associated with colic or diarrhea.

As an antidote for parasympathomimetic drugs, 1 mL for each 7.5 lbs of body weight. It is suggested that 1/4 of the dosage be injected intravenous and the remainder intramuscular or subcutaneous.

Warning

Poisonous alkaloid.

Keep out of reach of children.

Antidotes: Warmth, emetics, cholinergics.

For additional information about adverse drug experience reporting for animals contact FDA at 1-888-FDA-VETS or http://www.fda.gov/AnimalVeterinary/SafetyHealth

Questions? (855) 724-3461

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Information from PetPlace, by Dr. Dawn Ruben:

• Atropine is administered to block the effect of certain nervous system impulses (acetylcholine) on receptors throughout the body. In animals, like dogs and cats, it is most often used when an animal is undergoing anesthesia for surgery to block the undesirable effects of nervous system stimulation.
• The involuntary nervous system is divided into the sympathetic (flight or fight response) and parasympathetic branches. In general, these two systems oppose each other.
• When stimulated, the sympathetic system increases heart rate, blood pressure, and cardiac activity. The pupils dilate and gastrointestinal function reduces.
• The parasympathetic system, working largely through a nerve called the vagus nerve, slows heart rate, reduces blood pressure, and stimulates gastrointestinal function, salivation, and digestion.
• Cells contain targets, called receptors, that are stimulated by chemicals released from nerves. In the parasympathetic system, the chemical transmitter released by nerves is acetylcholine and the receptors are called muscarinic receptors.
• Atropine blocks the muscarinic receptor and thereby inhibits the effect of acetylcholine, reducing the parasympathetic activity of this chemical.
• Therefore, atropine belongs to the class of drugs known as anti-muscarinic agents. Sometimes they are also called “anti-cholinergics” or “parasympatholytics,” terms that also describe the actions.
• When the muscarinic part of the parasympathetic nervous system is blocked, the sympathetic system becomes more prominent.
• Atropine is a prescription drug and can only be obtained from a veterinarian or by prescription from a veterinarian.
• Atropine is used prior to anesthesia for surgery to reduce drooling and respiratory tract secretions.
• Atropine is often administered with many anesthetic agents to prevent slowing of the heart rate.
• It is also used to treat dangerously slow heart rates and is an important drug in CPR.
• Atropine is an antidote for some insecticide (e.g. cholinesterase inhibitors) and mushroom poisonings.
• Atropine is also used to reduce drooling (salivation), vomiting and nausea.
  • Atropine will antagonize compounds that constrict the airways and cause coughing. Therefore, atropine, and similar compounds can be used in animals that may have difficulty breathing (such as asthma – like conditions).

• Precautions and Side Effects

  • While generally safe and effective when prescribed by a veterinarian, atropine can cause side effects in some animals.
  • Atropine should not be used in animals with known hypersensitivity or allergy to the drug.
  • It should also not be used if a gastrointestinal obstruction or infection is suspected.
  • Do not use atropine if inflammation of the large bowel is present.
  • Never give atropine to an animal that has been diagnosed as having glaucoma.
  • Atropine may interact with other medications. Consult with your veterinarian to determine if other drugs your pet is receiving could interact with atropine. Such drugs include certain antihistamines, meperidine, diazepam, metoclopramide and procainamide.
  • Atropine should be used with caution in animals with rapid heart rates or with impaired kidney, heart or liver function.
  • When the eye formulation for atropine is given, the animal, especially cats, may profusely drool due to the bitter taste of the drug.
  • Some side effects include dry mouth, constipation, central nervous system stimulation (excitement), blurred vision, drowsiness or ataxia (a wobbly walking pattern or gait). Because of the dry mouth, atropine may cause some animals to drink excess water.

Information from Plumb's Veterinary Handbook, 7th Edition, by Donald C. Plumb:

Atropine is contraindicated in patients with narrow-angle glaucoma, synechiae (adhesions) between the iris and lens, hypersensitivity to anticholinergic drugs, tachycardias secondary to thyrotoxicosis or cardiac insufficiency, myocardial ischemia, unstable cardiac status during acute hemorrhage, GI obstructive disease, paralytic ileus, severe ulcerative colitis, obstructive uropathy, and myasthenia gravis (unless used to reverse adverse muscarinic effects secondary to therapy). Atropine may aggravate some signs seen with amitraz toxicity, leading to hypertension and further inhibition of peristalsis.

Antimuscarinic agents should be used with extreme caution in patients with known or suspected Gi infections. Atropine or other antimuscarinic agents can decrease GI motility and prolong retention of the causative agent(s) or toxin(s) resulting in prolonged clinical signs. Antimuscarinic agents must also be used with extreme caution in patients with autonomic neuropathy. 

Atropine is reportedly not effective in treating bradycardias in puppies before 14 days of age or kittens younger than 11 days old. It may also damage hypoxic myocardia in neonates. 

Glycopyrrolate is usually the anticholinergic of choice when treating rabbits, as a large percentage have endogenous atropinesterase present.

Antimuscarinic agents should be used with caution in patients with hepatic or renal disease, geriatric or pediatric patients, hyperthyroidism, hypertension, CHF, tachyrrythmias, prostatic hypertrophy, or esophageal reflux.

Adverse effects are basically extensions of the drug's pharmacologic effects and are generally dose related. At usual doses, effects tend to be mild in relatively healthy patients. The more severe effects listed tend to occur with higher or toxic doses. GI effects can include dry mouth (xerostomia), dysphagia, constipation, vomiting, and thirst. GU effects may include urinary retention or hesitancy. CNS effects may include stimulation, drowsiness, ataxia, seizures, respiratory depression, etc. Ophthalmic effects include blurred vision, pupil dilation, cycloplegia, and photophobia. Cardiovascular effects include sinus tachycardia (at a higher dose), bradycardia (initially or at very low doses), hypertension, hypotension, arrhythmias (ectopic complexes), and circulatory failure. 

Atropine may interact with the following drugs:amantadine, other anticholinergic agents, anticholinergic muscle relaxants, antihistamines, disopyramide, meperidine, phenothiazines, procainamide, primidone, tricycline antidepressants, alpha-2 agonists, amitraz, antacids, corticosteroids, digoxin, ketoconazole, and metoclopramide.