Name of the Antimuscarinics drugs
- Atropine
- Hyoscine
- Procyclidine
Mechanism of Action:
Antimuscarinic medications are a group of anticholinergic agents, specifically known for blocking the activity of muscarinic receptors. These receptors play an important role in mediating the functions of the parasympathetic nervous system, which controls many involuntary functions to conserve energy, including the contraction of smooth muscle, dilation of blood vessels, increased bodily secretions, gastrointestinal activity, and heart rate.
Therefore, antimuscarinics work by inhibiting the functions of the parasympathetic nervous system.
Indications
- Atropine
- Bradycardia
- Mydriasis and cycloplegia
2. Procyclidine
- Parkinsonism
3. Hyoscine
- Sympotamatic relief of GI/GU muscle spasm
- Urinary incontinence
| Atropine |
| Dosage Forms & Strengths: Tablet: 0.4mg Sialorrhea, Pylorospasm & Other Spastic Conditions of the Gastrointestinal Tract: 0.4 mg PO q4-6hr PRN Pediatric : Tablet: 0.4mg Sialorrhea, Pylorospasm & Other Spastic Conditions of the Gastrointestinal Tract 3-7 kg: 0.1 mg, 8-11 kg: 0.15 mg, 11-18 kg: 0.2 mg, 18-29 kg: 0.3 mg, ≥30 kg: 0.4 mg Alternate Dosing :<5 kg: 0.02 mg/kg/dose initially, then q4-6hr PRN •≥5 kg: 0.01-0.02 mg/kg PO q4-6hr PRN; not less than 0.1 mg/dose, not to exceed 0.4 mg/dose |
| Intramuscular device: 0.25mg/0.3mL, 0.5mg/0.7mL, 1mg/0.7mL, 2mg/0.7mL injectable solution: 0.05mg/mL, 0.1mg/mL, 0.4mg/mL, 0.8mg/mL, 1mg/mL |
| Restrict dose to 2-3 mg (0.03-0.04 mg/kg) in patients with ischemic heart disease, to avoid atropine-induced tachycardia, increased myocardial oxygen demand and potential for worsening cardiac ischemia or increasing infarction size |
| Anaesthesia Premedication: 0.4-0.6 mg IV/IM/SC 30-60 minutes before anaesthesia; repeat q4-6hr PRN Sinus Bradycardia (ACLS): 0.5-1 mg or 0.04 mg/kg IV q5min, no more than 3 mg ET: Some experts suggest 2-3 times IV dose diluted in3- 5 mL sterile water for injection/NS (sterile water for injection may facilitate absorption better than NS, but may produce more negative effect on arterial oxygen pressure) Bronchospasm: 0.025 mg/kg in 2.5 mL NS q6-8hr via nebulizer; no more than 2.5 mg/dose |
| Organophosphate or Carbamate (Cholinesterase Inhibitors) Poisoning : AUTO INJECTOR Two or more mild symptoms of nerve agent (nerve gas) or insecticide exposure: Administer 1 injection (2 mg) IM Wait 10-15 minutes for drug to take effect; if, after 10-15 minutes, patient does not develop any severe symptoms, no additional injections recommended If after first dose, patient develops severe symptoms, administer 2 additional injections IM in rapid succession If possible, a person other than patient should administer second and third 2 mg autoinjector If patient is either unconscious or has any severe symptoms, immediately administer 3 injections intramuscularly into patient’s mid-lateral outer thigh in rapid succession. |
| PEDIATRICS : intramuscular device : 0.25mg/0.3mL, 0.5mg/0.7mL, 1mg/0.7mL, 2mg/0.7mL injectable solution : 0.05mg/mL, 0.1mg/mL, 0.4mg/mL, 0.8mg/mL, 1mg/mL |
| Anaesthesia Premedication: <5 kg: 0.02 mg/kg/dose 30-60 minutes preop; then q4-6hr PRN >5 kg: 0.01-0.02 mg/kg IV/IM/SC; no more than 0.4 mg Sinus Bradycardia: 0.02 mg/kg IV/IO q5min for 2-3 doses PRN; single dose no less than: 0.1 no more than 0.5 mg (children), 1 mg (adolescents)Total: No more than: 1 mg (children), 2 mg (adolescents) ET: Some experts suggest 0.03 mg/kg, diluted in NS Bronchospasm: 0.025-0.05 mg/kg in 2.5 mL NS q6-8hr via nebulizer; no more than 2.5 mg/dose |
| Organophosphate or Carbamate (Cholinesterase Inhibitors) Poisoning : IV: 0.03-0.05 mg/kg IV/IM/IO/ET q10-20min PRN to effect; then q1-4hr for at least 24 hours |
| Hyoscine |
| Availability: Transdermal System: (Trans-Derm Scop): 1.5 mg |
| Administration/handling: Transdermal • Apply patch to hairless area behind one ear. • If dislodged or on for more than 72 hrs, replace with fresh patch. • Do not cut/trim. • Limit contact with water |
| Prevention of Motion Sickness Transdermal: Adults: One system at least 4 hrs prior to exposure and q72h as needed. |
| Post-op Nausea/Vomiting Transdermal: Adults, elderly: 1 system no sooner than 1 hr before surgery and removed 24 hrs after surgery. |
Cautions and contraindications:
- Myasthenia gravis
- Paralytic ileus
- Pyloric stenosis
- Prostatic enlargement
- Narrow angle glaucoma
- Urinary obstruction
- Gastric ulcers.
Side – Effects:
- Constipation
- Urinary retention
- Dry mouth
- Blurred vision
- Drowsiness
- Sore throat
- Tachycardia
- Mood changes
- Hallucinations
- Disorientation
Metabolism and Half – life:
Highly variable – t ½ for atropine is 2-4h and metabolized by the liver to inactive metabolites; t ½ for hyoscine is 5h; t ½ for procyclidine is 12hrs.
Monitoring:
Administration of atropine requires cardiac and blood pressure monitoring.
Drug interactions:
The increased sedative effect when hyoscine gave with alcohol.
Nursing Considerations:
- As with all anticholinergics, use with caution with the elderly, because elderly patients may react with agitation or drowsiness.
- Heat stroke may occur in the presence of high temperatures.
- Immediately report symptoms of overdose: urine retention, abnormal heartbeat, dizziness, passing out, difficulty breathing, weakness, or tremors.
- Physostigmine has been used to reverse anticholinergic effects.
Patient Teaching & Education:
- Advise patients that use of these medications may cause dizziness and drowsiness, so patients should be aware of potential impact on their level of alertness. Additionally, use of medications may cause dry mouth, and frequent oral hygiene is encouraged.
- The use of atropine may cause urinary retention in males with benign prostatic hypertrophy (BPH).
Important Points:
- Hyoscine may be used for GI colic and excessive respiratory secretions in end-of- life care.
- It is also used to reduce respiratory secretions during anesthesia.
- Atropine is used as part of the Resuscitation Council UK guidelines for symptomatic bradycardia and in cardiac arrests when pulseless electrical activity is below 60 complexes per minute.
REFERENCES
- Robert Kizior, Keith Hodgson, Saunders Nursing Drug handbook,1st edition 2024, Elsevier Publications. ISBN-9780443116070
- McGraw Hill- Drug Handbook, Seventh Edition, 2013, McGraw Hill Education Publications,9780071799430.
- April Hazard, Cynthia Sanoski, Davi’s Drug Guide for Nurses -Sixteenth Edition 2019, FA Davis Company Publications,9780803669451.
- Jones and Bartlet, Pharmacology for Nurses, Second Edition, 2020, Jones and Bartlet Learning Publications, ISBN 9781284141986.
- Nursebro.com, Search – Nursebro
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