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Atropine Sulphate

Anticholinergic, Antidote

Generic name: Atropine sulphate (ah´troe-peen sul´fate)
Brand names: Tropine 0.6mg injection. Atrops 0.6mg injection
Dosage form: Atropine is available in 0.6mg/ml, 400-, 500-, and 540-mcg/mL injection and 15-mg/mL injection. Injectable solution (0.4 mg/mL; 1 mg/mL), Intramuscular solution (2 mg/0.7 mL), Intravenous solution (0.05 mg/mL; 0.1 mg/mL; 0.4 mg/mL; 0.4 mg/mL-NaCl 0.88% preservative-free; 0.4 mg/mL-NaCl 0.9%; 1 mg/mL)
Drug class: Anticholinergic chronotropic agent, Antispasmodic, Antidote

Pharmacology and Mechanism of Action: An anticholinergic agent, also known as a para-sympatholytic, works by competitively blocking the effects of acetylcholine or other cholinergic stimulants at postganglionic parasympathetic/muscarinic receptors. As an antimuscarinic, it inhibits cholinergic stimulation, leading to reduced gastrointestinal motility and secretions, decreased respiratory secretions, an increase in heart rate (due to its antivagal effect), and mydriasis.

  • At low doses, atropine inhibits salivation, bronchial secretions, and sweating (though not in horses).
  • At moderate systemic doses, it causes pupil dilation, inhibits accommodation, and increases heart rate.
  • High doses reduce motility in the gastrointestinal and urinary tracts, while very high doses can suppress gastric secretion.

Pharmacokinetics: Atropine sulfate is efficiently absorbed through oral administration, intramuscular injection, inhalation, or endotracheal administration. When administered intravenously, peak effects on heart rate are typically observed within 3–4 minutes. The drug is widely distributed throughout the body, crossing into the CNS, placenta, and small amounts can also be found in milk. Atropine is metabolized in the liver and excreted in the urine, with approximately 30–50% of a dose being eliminated unchanged. The plasma half-life of atropine in humans is reported to be between 2–3 hours.

Indications and Clinical Uses:

  • Atropine is primarily used as an Preanesthetic or other procedures to raise heart rate and reduce respiratory and gastrointestinal secretions.
  • Treat sinus bradycardia, sinoatrial arrest, incomplete AV block
  • It is the drug of choice for counteracting excessive vagal stimulation in certain clinical situations.
  • Additionally, atropine serves as an antidote for organophosphate poisoning, antidote for overdoses of cholinergic agents (e.g., physostigmine, etc.),carbamate, muscarinic mushroom, blue-green algae intoxication.
  • To treat Hypersialism

Instructions for Use: Atropine is typically used as an adjunct during anesthesia or other procedures. In dogs, a dose of 0.06 mg/kg has proven more effective than 0.02 mg/kg. Atropine can also be used in cardiac resuscitation; however, high doses may lead to sustained tachycardia and increased myocardial oxygen demand. For cardiac resuscitation, an intravenous dose of 0.04 mg/kg can be used, while lower doses of 0.01 mg/kg are recommended for treating sinus bradycardia.

Precautions: Dose dependent and anticholinergic Side effects include Mydriasis/cycloplegia, Dry mouth(xerostomia), ileus, constipation, Initial bradycardia then tachycardia, Slow gut and urine retention.
Contraindications: Do not use in patients with glaucoma, intestinal ileus, GI obstructive disease- gastroparesis, suspected GI infections, tachycardia, obstructive uropathy
High doses (e.g., 0.04 mg/kg) increase oxygen demand.

Drug Interactions: Do not mix with alkaline solutions. Atropine(Anticholinergic) will antagonize the effects of any cholinergic drugs administered (e.g., metoclopramide).

Dogs:

  • Preanesthetic adjuvant: 0.02-0.04 mg/kg q6-8h IV, IM, or SQ (complete dose range has been from 0.01 mg/kg to 0.06 mg/kg, depending on the indication).
  • Sinus bradycardia: 0.005-0.01 mg/kg, but for use during cardiopulmonary resuscitation (CPR) up to 0.04 mg/kg.
  • For organophosphate and carbamate toxicosis: 0.2-0.5 mg/kg as needed, 1/4th dose IV, and reminder dose  IM, or SQ.
  • For treatment of bronchoconstriction: 0.02–0.04 mg/kg for a duration of effect of 1–1.5 hours

Cats:

  • Preanesthetic adjuvant: 0.02-0.04 mg/kg  IV, IM, or SC.
  • For organophosphate and carbamate toxicosis: 0.2-0.5 mg/kg as needed, 1/4th dose IV, and reminder dose  IM, or SQ.

N.B. : In large animals, atropine has a potent effect on inhibiting gastrointestinal motility.

Ferrets:

  • As a premed: 0.05 mg/kg SC or IM

Horse

  • Antidote to organophosphates or cholinesterase inhibitors: 0.02-0.04 mg/kg IM or SQ, and repeat as needed.
  • Recurrent airway obstruction (RAO): 0.022 mg/kg, once, IV.

Pigs

  • Antidote to organophosphates or cholinesterase inhibitors: 0.1 mg/kg IV followed by 0.4 mg/kg IM.
  • Anesthesia adjunct: 0.02 mg/kg IV or 0.04 mg/kg IM.

Ruminants

  • Antidote to organophosphates or cholinesterase inhibitors: 0.1 mg/kg IV, followed by 0.4 mg/kg IM and repeat q3–4h for 1–2 days as needed. or  0.5 mg/kg (average dose); give ¼th of the dose IV and the remainder SC or IM; may repeat q3–4h for 1–2 days.
  • Anesthesia adjunct to prevent salivation: 0.02 mg/kg IV or 0.04 mg/kg IM.\

 

Patient Monitoring and Laboratory Tests: Monitor patient’s heart rate and rhythm, Thirst/appetite; urination/defecation capability, Mouth/secretions dryness

Stability and Storage :Store in a tightly sealed container at room temperature. Atropine sulfate for injection should be stored at room temperature; avoid freezing.

Drug Compatibility: Atropine sulfate is reported physically incompatible with norepinephrine bitartrate, metaraminol bitartrate, methohexital sodium, and sodium bicarbonate. Do not mix with alkaline solutions.