====== Antimuscarinics / AntiCholinergics (Muscarinic Antagonists) ======

Antimuscarinics block acetylcholine at muscarinic receptors and therefore inhibit parasympathetic activity.

They produce predictable organ effects — remembering the physiology is more important than memorizing drugs.

<WRAP center round important 70%>
Antimuscarinics = "Turn OFF rest-and-digest" → Sympathetic-like effects
</WRAP>

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===== Muscarinic Receptors =====

<WRAP center 80%>
^ Receptor ^ Location ^ Normal Function ^
| M1 | CNS, gastric parietal cells | Cognition, acid secretion |
| M2 | Heart | ↓ Heart rate |
| M3 | Smooth muscle & glands | Contraction & secretion |
</WRAP>

Blocking these receptors produces opposite physiologic effects.

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===== Core Physiologic Effects =====

<WRAP center round box 85%>
  * Dry as a bone → ↓ secretions  
  * Blind as a bat → mydriasis + cycloplegia  
  * Hot as a hare → ↓ sweating  
  * Red as a beet → vasodilation  
  * Mad as a hatter → delirium
</WRAP>

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===== Organ System Effects =====

^ Organ ^ Parasympathetic Action ^ Antimuscarinic Effect ^
| Eye | Constrict pupil | Mydriasis |
| Heart | Slow heart | Tachycardia |
| Lungs | Bronchoconstriction | Bronchodilation |
| GI | Motility & secretion | Constipation |
| Bladder | Detrusor contraction | Urinary retention |
| Glands | Salivation | Dry mouth |

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===== Major Clinical Uses =====

==== Bronchodilation ====
  * [[respiratory:antimuscarinics:ipratropium|Ipratropium]]
  * [[respiratory:antimuscarinics:tiotropium|Tiotropium]]
  * [[respiratory:antimuscarinics:aclidinium|Aclidinium]]
  * [[respiratory:antimuscarinics:umeclidinium|Umeclidinium]]
  * [[respiratory:antimuscarinics:glycopyrrolate|Glycopyrrolate]]
  * [[respiratory:antimuscarinics:revefenacin|Revefenacin]]

==== Overactive Bladder ====
  * [[gu:antimuscarinics:oxybutynin|Oxybutynin]]
  * [[gu:antimuscarinics:tolterodine|Tolterodine]]
  * [[gu:antimuscarinics:solifenacin|Solifenacin]]
  * [[gu:antimuscarinics:darifenacin|Darifenacin]]
  * [[gu:antimuscarinics:trospium|Trospium]]

==== GI Antispasmodic ====
  * [[gi:antispasmodics:dicyclomine|Dicyclomine]]
  * [[gi:antispasmodics:hyoscyamine|Hyoscyamine]]

==== Motion Sickness / CNS ====
  * [[cns:antimuscarinics:scopolamine|Scopolamine]]
  * [[cns:antimuscarinics:benztropine|Benztropine]]

==== Ophthalmic Mydriasis ====
  * [[ophthalmology:antimuscarinics:atropine|Atropine]]
  * [[ophthalmology:antimuscarinics:tropicamide|Tropicamide]]
  * [[ophthalmology:antimuscarinics:cyclopentolate|Cyclopentolate]]

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===== Adverse Effects =====

All antimuscarinics share predictable toxicity:

  * Dry mouth
  * Constipation
  * Urinary retention
  * Blurred vision
  * Tachycardia
  * Delirium (elderly)

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===== Contraindications =====

  * Narrow-angle glaucoma
  * Urinary retention / BPH
  * Elderly with cognitive impairment

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===== Clinical Pearls =====

<WRAP round tip 90%>
If a symptom involves excessive secretion or smooth muscle contraction → antimuscarinics treat it.
</WRAP>

Common real-world uses:
  * COPD bronchodilation
  * Overactive bladder
  * Motion sickness
  * Organophosphate poisoning antidote (atropine)

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===== Related Systems =====

  * [[respiratory:antimuscarinics:start|Respiratory Antimuscarinics]]