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Ch. 11 anticholinergic drugs

Ch. 11 anticholinergic drugs. R1. 이송이. Anticholinergic Drugs. Anticholinergic drugs : group of drugs that block muscarinic receptors Commonly Used Atropine Scopolamine Glycopyrrolate. Mechanism of Action. Anticholinergics Muscarinic Rc. subgroups M1 – Neuronal M2 – Cardiac

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Ch. 11 anticholinergic drugs

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  1. Ch. 11 anticholinergic drugs R1. 이송이

  2. Anticholinergic Drugs • Anticholinergic drugs : group of drugs that block muscarinic receptors • Commonly Used • Atropine • Scopolamine • Glycopyrrolate

  3. Mechanism of Action • Anticholinergics • Muscarinic Rc. subgroups • M1 – Neuronal • M2 – Cardiac • M3 - Glandular Ester Link Organic Base Aromatic Acid Ester linkage is essential for effective binding of Anticholinergic s to Acetylcholine Rc. Competitively blocks Ach & Prevents further activation

  4. Clinical Pharmacology • In clinical doses only Muscarinic Receptors are blocked  Extent of effect depends on the degree of baseline vagal tone

  5. Clinical Pharmacology • Cardiovascular • SA node  tachycardia useful in reversing bradycardia d/t vagal reflexes (e.g. baroreceptor reflex, peritoneal stimuli, oculocardiac reflex) • AV node facilitation of conduction PR interval shortening • Ventricle, Pph. Vasculature little effect • Modestly enhance sympathetic activity • Large dose dilatation of cutaneous vessels (atropine flush)

  6. Clinical Pharmacology • Respiratory • Inhibit secretions of respiratory mucosa (nose ~ bronchi) • Relaxation of bronchial smooth musculature • Reduce airway resistance • Increase anatomic dead space • Effects pronounced in COPD or Asthma pts.

  7. Clinical Pharmacology • Cerebral • Cause a spectrum of CNS effects ; stimulation ~ depression • Depends on drug choice and dose • Stimulation : excitation, restlessness or hallucination • Depression : sedation & amnesia • Physostigmine : reverses these actions

  8. Clinical Pharmacology • Gastrointestinal • Salivary & Gastric secretions are reduced • Intestinal motility and peristalsis decrease • Prolong gastric emptying time • LES is reduced • Risk of aspiration pneumonia increases • Opthalmic : Mydriasis & Cycloplegia • GU : Decreased ureter & bladder tone urinary retention • Thermoregulation : Inhibit sweat gl. rise in body temp. (atropine fever)

  9. Specific Anticholinergic Drugs

  10. Atropine • Physical Structure • Dosage • Premedication • 0.001-0.02mg/kg (up to 0.4-0.6mg in adults) IV or IM • Treating severe bradycardia – up to 2mg

  11. Atropine • Clinical Consideration • Potent effect on the heart & bronchial smooth muscle • Treatment in bradyarrhythmias • CAD pts may not tolerate the increased myocardial O2 demand & decreased O2 supply • Ipratropium bromide (Atropine derivative) : used in the treatment of bronchospasm • CNS effects : minimal • Mild postop. memory loss • Toxic doses  excitatory reaction • Antisialagogue effect : 0.01 ~ 0.02 mg/kg IM • Use cautiously in 1. Narrow angle glaucoma 2. PH 3. Bladder Obx

  12. Scopolamine • Physical Structure • Dosage • Premedication • 0.01-0.02mg/kg IM (up to 0.4-0.6mg in adults)

  13. Scopolamine • Clinical Considerations • More potent antisialagogue • Greater CNS effects • Causes Drowsiness & Amnesia • Restlessness & Delirium is possible • Prevents motion sickness • Pronounced ocular effects • Should be avoided in closed angle glaucoma

  14. Glycopyrrolate • Physical Structure • Dosage • Half dose of Atropine • Premedication • 0.005-0.001mg/kg (up to 0.2-0.3mg in adults)

  15. Glycopyrrolate • Clinical Considerations • cannot cross the BBB Devoid of CNS & Opthalmic activity • Potent inhibitor of salivary gl. & respiratory tract secretion • HR increases after IV injection but not IM • Longer duration of action than Atropine (2~4hr vs. 30 min)

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