Atropine Injection

Introduction

Atropine sulfate is a naturally occurring anticholinergic agent that is primarily used to treat bradycardia (slow heart rate), reduce salivation and bronchial secretions during surgery, and as an antidote to organophosphate poisoning. It works by blocking the action of acetylcholine, a neurotransmitter involved in the parasympathetic nervous system, leading to increased heart rate and decreased glandular secretions.

Uses

Atropine sulfate is used in several medical conditions, including:

Bradycardia (to increase heart rate)
Pre-anesthetic to reduce secretions in the respiratory tract
Organophosphate poisoning antidote
Mydriasis (dilation of the pupils) for ophthalmic procedures
Relief of gastrointestinal spasms
Treatment of peptic ulcers (in the past, though less common now)

Brand Name	Atropine
Type	Injection
Weight	0.6 mg/ml
Generic	Atropine Sulfate
Manufacturer	Chemist Laboratories Ltd.
Available in	English বাংলা

Mechanism of Action

Atropine sulfate is an antimuscarinic agent that works by blocking muscarinic receptors in the body, inhibiting the action of acetylcholine. This results in various effects, including increased heart rate, decreased secretion of glands, dilation of pupils, and relaxation of smooth muscle in the gastrointestinal and urinary tracts.

How Long Does It Take to Work?

Atropine sulfate typically takes effect within minutes when administered intravenously or intramuscularly. The onset of action is usually within 1 to 2 minutes when given via IV, and it can take up to 30 minutes when administered via IM injection. The duration of action can last from 30 minutes to several hours depending on the route of administration and the dose.

Absorption

Atropine sulfate is rapidly absorbed when given via intravenous (IV) or intramuscular (IM) routes. It is also absorbed through the gastrointestinal tract when administered orally, but oral administration is less common for emergency situations.

Route of Elimination

Atropine sulfate is metabolized in the liver and excreted primarily through the kidneys. Approximately 50% of the drug is excreted unchanged in the urine, with the remainder being excreted as metabolites.

Dosage

Pre-anaesthetia:

Dog & Cat: 1 ml/25 kg body weight subcutaneously.
Sheep/Goat: 1 ml/5 kg body weight intravenously.

Treatment: Intramuscular/Subcutaneous use only.

Cattle/Horse: 1.5-3.0 ml/50 kg body weight.
Sheep/Goat: 0.8-1.6 ml/10 kg body weight.
Dog/Cat: 0.3-0.5 ml/10 kg body weight
Pigs: 0.2-0.4 ml/10 kg body weight.

Organophosphorus/Mushroom Poisoning: 0.25-2.0 ml/10 kg body weight upto 5 ml/10 kg body weight subcutaneously. In severe cases, 1/4 th of the dose to be administered by IV/IM and the remainder by SC. This dose can be repeated on an interval of 4 to 6 hours until clinical signs of poisoning relieved. Or as directed by the veterinary physician.

The dosage of atropine sulfate depends on the condition being treated:

Bradycardia: 0.5 to 1 mg IV every 3 to 5 minutes as needed (maximum dose of 3 mg).
Pre-anesthetic: 0.4 to 0.6 mg IM or IV 30 to 60 minutes before surgery.
Organophosphate poisoning: 2 mg IV or IM every 5 to 10 minutes until symptoms are controlled.
Mydriasis (for eye examination): 1-2 drops of a 1% solution in the eye.

Administration

Atropine sulfate can be administered through various routes, including intravenous (IV), intramuscular (IM), subcutaneous (SC), oral, and ophthalmic (eye drops). The route depends on the clinical situation. IV administration is commonly used in emergencies like bradycardia or poisoning, while IM or SC is used for pre-anesthetic purposes. Ophthalmic drops are used for pupil dilation in eye examinations.

Side Effects

Common side effects of atropine sulfate include:

Dry mouth
Blurred vision
Tachycardia (increased heart rate)
Constipation
Urinary retention

Serious side effects may include:

Severe tachycardia or arrhythmias
Confusion or hallucinations (especially in older adults)
Difficulty breathing
Severe allergic reactions (rare)

Toxicity

Atropine toxicity can occur with high doses and presents with symptoms such as severe dry mouth, blurred vision, photophobia, hyperthermia, delirium, and seizures. In severe cases, it can cause respiratory failure or death. Treatment includes supportive care, administration of activated charcoal (if appropriate), and the use of cholinesterase inhibitors such as physostigmine to counteract the effects of atropine.

Precautions

Atropine sulfate should be used with caution in patients with certain conditions:

Glaucoma, as it can increase intraocular pressure
Prostatic hypertrophy, as it can worsen urinary retention
Myasthenia gravis, as it may exacerbate muscle weakness
Coronary artery disease, as it can increase heart rate and worsen ischemia

Interaction

Atropine sulfate may interact with:

Antihistamines, leading to increased anticholinergic effects
Tricyclic antidepressants, which may enhance the anticholinergic effects
Antipsychotic medications, increasing the risk of anticholinergic side effects
Cholinesterase inhibitors (e.g., donepezil), which may reduce the efficacy of atropine in treating bradycardia

Disease Interaction

Atropine should be used with caution in patients with:

Glaucoma
Obstructive uropathy
Gastrointestinal obstructive disorders
Ulcerative colitis, as it may exacerbate symptoms

Drug Interaction

Atropine may interact with:

Other anticholinergic agents (e.g., scopolamine), leading to additive effects
MAO inhibitors, which may increase atropine’s effects
Beta-blockers, potentially reducing the heart rate-modulating effects of both drugs

Food Interactions

Food does not have a significant impact on the efficacy or absorption of atropine. However, certain foods that cause dry mouth or dehydration (e.g., caffeine-containing beverages) may worsen anticholinergic side effects like dry mouth or constipation.

Pregnancy Use

Atropine is classified as pregnancy category C. It should be used during pregnancy only if the potential benefit outweighs the risks to the fetus. There is limited data on its safety in pregnancy, so caution is advised.

Lactation Use

Atropine can be excreted in breast milk in small amounts. While it is generally considered safe for short-term use during lactation, prolonged use may result in adverse effects in the nursing infant, including decreased milk production due to atropine's anticholinergic effects.

Acute Overdose

Acute overdose of atropine sulfate may cause symptoms such as severe dry mouth, blurred vision, hallucinations, hyperthermia, and coma. In extreme cases, it can result in respiratory failure or death. Treatment includes supportive care, cooling for hyperthermia, and the use of cholinesterase inhibitors like physostigmine as an antidote.

Contraindication

Atropine sulfate is contraindicated in patients with:

Narrow-angle glaucoma
Tachyarrhythmias
Severe prostatic hypertrophy with urinary retention
Hypersensitivity to atropine or any of its components

Use Direction

Atropine sulfate is used based on the indication. For bradycardia, it is administered intravenously in emergency situations. Pre-anesthetic doses are administered IM or SC. For ophthalmic use, it is applied as eye drops. Dosage and frequency depend on the condition being treated and the patient's response to therapy.

Storage Conditions

Atropine sulfate should be stored at room temperature (20-25°C), protected from light and moisture. It should be kept out of reach of children and discarded if past its expiration date.

Volume of Distribution

The volume of distribution of atropine is approximately 3-4 L/kg, indicating wide tissue distribution, including penetration into the central nervous system (CNS).

Half-Life

The half-life of atropine is approximately 2 to 4 hours in adults, but this can be longer in elderly patients due to reduced clearance.

Clearance

Atropine is primarily cleared through the kidneys, with about 50% excreted unchanged in the urine. The remaining fraction is metabolized in the liver. Reduced clearance may be seen in patients with renal or hepatic impairment.

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