atropine

Actions and Spectrum: 

• atropine is a medication that belongs to a class of drugs known as anticholinergics. It acts by blocking the action of acetylcholine, a neurotransmitter in the parasympathetic nervous system, which is responsible for the “rest and digest” functions of the body. 
• atropine’s mechanism of action involves binding to and inhibiting the muscarinic receptors in the parasympathetic nervous system, thereby blocking the effects of acetylcholine. This leads to an increase in the activity of the sympathetic nervous system, which is responsible for the “fight or flight” response. 

DRUG INTERACTION

Contraindicated  

Serious Use Alternative  

Monitor Closely  

Minor  

Frequency not defined 

Coma 

Delirium 

Drowsiness 

Headache 

Nervousness 

Flushing 

Tachycardia 

Ataxia 

Confusion 

Dizziness 

Hallucinations 

Insomnia 

Arrhythmia 

Hypotension 

Palpitation 

Pulmonary edema 

Constipation 

Bloating 

Dyspnea 

Delayed gastric emptying 

Loss of taste 

Vomiting 

Xerostomia 

Fever 

Urticaria 

Urinary hesitancy and retention 

Anaphylaxis 

Blurred vision 

Ocular pressure increased 

Paralytic ileus 

Nasal dryness 

Rash 

Scarlantiniform rash 

Angle-closure glaucoma 

Dry eyes 

Nausea 

Anhidrosis 

Contraindications/caution: 

Contraindications: 

• Hypersensitivity: Patients hypersensitive or allergic to atropine or its derivatives should not receive this medication. 
• Glaucoma: atropine can increase intraocular pressure and exacerbate closed-angle glaucoma, making it contraindicated in patients with this condition. 
• Gastrointestinal obstruction: atropine can cause smooth muscle relaxation, which may worsen gastrointestinal obstruction. 
• Prostatic hypertrophy: atropine can cause urinary retention in patients with prostatic hypertrophy, making it contraindicated in these patients. 
• Cardiac arrhythmias: atropine can worsen some cardiac arrhythmias, particularly those related to ventricular tachycardia. 
• Myasthenia gravis: atropine can worsen the symptoms of myasthenia gravis, making it contraindicated in these patients. 
• Pregnancy and breastfeeding: atropine should be used cautiously during pregnancy and breastfeeding, as its safety in these populations has not been established. 

Caution: 

• Elderly patients: Elderly patients may be more sensitive to the effects of atropine, particularly those related to the central nervous system (CNS), such as confusion and delirium. 
• Patients with cardiac disease: atropine can increase heart rate and worsen certain cardiac arrhythmias, so caution should be taken when administering it to patients with pre-existing cardiac disease. 
• Patients with liver or kidney disease: atropine is metabolized in the liver and excreted by the kidneys, so caution should be taken when administering it to patients with impaired liver or kidney function. 
• Concurrent use of other medications: atropine may interact with other medications, particularly those with anticholinergic effects, such as tricyclic antidepressants, antihistamines, and antipsychotics. 
• Patients with hyperthyroidism: atropine can worsen the symptoms of hyperthyroidism, such as tachycardia and hypertension. 
• Patients with Down syndrome: Individuals with Down syndrome may be more sensitive to the CNS effects of atropine and may be more prone to developing delirium or confusion. 
• Patients with ulcerative colitis: atropine can worsen symptoms of ulcerative colitis, so caution should be taken when administering it to patients with this condition. 

Pregnancy consideration: Insufficient data available 

Lactation: Excretion of the drug in human breast milk is unknown 

Pregnancy category: 

Category A: well-controlled and Satisfactory studies show no risk to the fetus in the first or later trimester.   

Category B: there was no evidence of risk to the fetus in animal studies, and there were not enough studies on pregnant women. 

Category C: there was evidence of risk of adverse effects in animal reproduction studies, and no adequate evidence in human studies must take care of potential risks in pregnant women.    

Category D: adequate data with sufficient evidence of human fetal risk from various platforms, but despite the potential risk, and used only in emergency cases for potential benefits.    

Category X: Drugs listed in this category outweigh the risks over benefits. Hence these categories of drugs need to be avoided by pregnant women.    

Category N: There is no data available for the drug under this category 

Pharmacology: 

• atropine is a medication that belongs to the class of anticholinergic drugs, which means it blocks the effects of the neurotransmitter acetylcholine in the body. 
• atropine works by competitively inhibiting acetylcholine binding to its receptors, thereby preventing its stimulatory effects on the parasympathetic nervous system.  
• This results in an increase in heart rate, dilation of the pupils, decreased secretion of saliva and other secretions, and relaxation of smooth muscle in the bronchi and gastrointestinal tract. 

Pharmacodynamics: 

The pharmacodynamics of atropine involves its effects on the cholinergic receptors in the body. atropine is a competitive antagonist of acetylcholine at muscarinic receptors found in the parasympathetic nervous system. 

When atropine binds to these receptors, it blocks the effects of acetylcholine, leading to a decrease in parasympathetic activity and an increase in sympathetic activity. This results in a variety of physiological effects, including: 

Increased heart rate: atropine blocks the effects of acetylcholine on the heart, leading to an increase in heart rate. 

• Bronchodilation: atropine relaxes the smooth muscle in the bronchi, leading to increased airflow and improved respiration. 
• Pupil dilation: atropine blocks the effects of acetylcholine on the pupillary sphincter muscle, leading to dilation of the pupils. 
• Decreased secretions: atropine reduces the secretion of saliva, sweat, and other bodily fluids. 
• Decreased gastrointestinal motility: atropine reduces the activity of smooth muscle in the gastrointestinal tract, leading to decreased motility and a reduction in the secretion of gastric acid. 

Pharmacokinetics: 

Absorption 

atropine can be administered via several routes, including oral, intravenous, intramuscular, and subcutaneous. The bioavailability of orally administered atropine is relatively low, with only about 25-30% of the dose being absorbed. In contrast, the bioavailability of parenterally administered atropine is much higher, approaching 100%.  

Distribution 

atropine is distributed widely throughout the body, with high concentrations found in organs such as the liver, kidneys, and brain. At therapeutic doses, atropine does not cross the blood-brain barrier easily, but at higher doses or in patients with compromised barrier function, central nervous system (CNS) effects may occur.  

Metabolism 

atropine is metabolized primarily in the liver by a process known as hydrolysis, which involves the breakdown of the molecule by water. The primary metabolite of atropine is tropic acid, which is excreted in the urine.  

Elimination and Excretion 

atropine and its metabolites are excreted primarily in the urine, with a small amount also eliminated in the feces. The elimination half-life of atropine is around 2.5 hours. 

Administration: 

• atropine can be administered via several routes, including oral, intravenous (IV), intramuscular (IM), and subcutaneous (SC). The appropriate route of administration depends on the clinical indication and the patient’s condition. 
• In emergencies, atropine is usually administered intravenously or intramuscularly to achieve rapid onset of action. The IV route is preferred for patients who are critically ill or who require immediate treatment, as it provides the fastest onset of action. The recommended IV dose of atropine for adults is 0.5 to 1 mg, repeated every 3 to 5 minutes to achieve the desired effect. 
• In non-emergency situations, atropine can be administered orally or subcutaneously. The oral route is commonly used to treat gastrointestinal disorders, such as irritable bowel syndrome, and the subcutaneous route is sometimes used to treat excessive sweating. The usual oral dose of atropine for adults is 0.4 to 0.6 mg, taken 2 to 4 times per day. 

Patient information leaflet 

Generic Name: atropine 

Why do we use atropine? 

atropine is a medication that can be used for various purposes, depending on the dose, route of administration, and clinical indication. Here are some of the common uses of atropine: 

• Bradycardia: atropine can be used to treat slow heart rates (bradycardia) by blocking the effects of the vagus nerve, which slows down the heart rate. It is often used in emergencies to increase the heart rate and improve cardiac output. 
• Anesthesia: atropine can reduce secretions and prevent bradycardia during surgery and anesthesia. 
• Gastrointestinal disorders: atropine can treat gastrointestinal disorders, such as irritable bowel syndrome, by reducing smooth muscle spasms and cramping. 
• Ophthalmology: atropine is used as an eye drop to dilate the pupil and relax the ciliary muscle, which is helpful for eye examinations and certain eye conditions, such as uveitis. 
• Respiratory disorders: atropine can reduce secretions and dilate the airways in patients with respiratory disorders, such as chronic obstructive pulmonary disease (COPD). 
• Poisoning: atropine can be used as an antidote for certain types of poisoning, such as organophosphate insecticide poisoning, by blocking the effects of acetylcholine in the nervous system.