13 Anticholinergic Rx Flashcards
Anticholinergic mechanism of action
Anti-muscarinic -
Ester linkage essential for effective binding to ACh receptor
Competitively blocks binding by ACh and prevents receptor activation
Receptor subtypes:
- M1: neuronal
- M2: cardiac
- M3: glandular
Cardiovascular Rx effects
SA node muscarinic receptor blockade
- Tachycardia - also reverses bradycardia due to vagal reflexes
- Paradoxical bradycardia with small IV doses - MoA unknown
- Shorten P-R interval, decreases vagal heart block
- Little effect on ventricular function of peripheral vasculature
Respiratory Rx effects
Inhibit secretions of respiratory tract (nose to bronchi)
Relax bronchial smooth musculature - reduces airway resistance & increases anatomic dead space - most pronounced in COPD/asthmatics
Cerebral Rx effects
Spectrum of CNS ranging from stimulation to depression
Gastrointestinal Rx effects
Reduce salivary secretions
Reduce gastric secretions (requires larger doses)
Decreased intestinal motility and peristalsis - prolong gastric emptying
Lower esophageal sphincter pressure reduced
Ophthalmic Rx effects
Mydriasis - pupillary dilation
Cycloplegia - inability to accommodate to near vision
Genitourinary Rx effects
Decrease ureter and bladder tone (b/c smooth muscle relaxation)
Leads to urinary retention
Thermoregulation Rx effects
Inhibition of sweat glands - rise to body temp
Atropine
Premed: 0.01-0.02 mg/kg (upto adult dose 0.4-0.6 mg)
Pts with CAD may not tolerate increased myocardia O2 demand and decreased O2 supply from tachycardia
Ipratropium bromide - derivative of atropine
Glcopyrrolate
Premed dose is 1/2 of atropine
Premed dose: 0.005-0.1 mg/kg (up to 0.2-0.3 mg in adults)
Cannot cross BBB
More inhibition of salivary and respiratory secretions than atropine
Longer duration than atropine (2-4 h vs 30 min) after IV admin
