====== Antimuscarinics (SAMA / LAMA) ======

{{tag>respiratory bronchodilator antimuscarinic}}

Antimuscarinics bronchodilate by blocking vagal bronchoconstriction rather than stimulating dilation.

They are the **foundation maintenance bronchodilators in COPD** and adjunct therapy in asthma.

<WRAP round tip 80%>
These medications are a respiratory application of  
[[autonomics:antimuscarinics|muscarinic receptor blockade]].
</WRAP>

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===== Drugs in Class =====

==== Short-Acting (SAMA) ====
  * [[respiratory:antimuscarinics:ipratropium|Ipratropium]]

==== Long-Acting (LAMA) ====
  * [[respiratory:antimuscarinics:tiotropium|Tiotropium]]
  * [[respiratory:antimuscarinics:umeclidinium|Umeclidinium]]
  * [[respiratory:antimuscarinics:glycopyrrolate|Glycopyrrolate]]
  * [[respiratory:antimuscarinics:aclidinium|Aclidinium]]
  * [[respiratory:antimuscarinics:revefenacin|Revefenacin]]

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===== Mechanism of Action =====

**Receptor Blocked**
  * M3 muscarinic receptor  
  (see [[autonomics:antimuscarinics|Autonomic Antimuscarinics]])

**Normal Physiology**
  * Vagus nerve → acetylcholine → bronchoconstriction + mucus secretion

**Drug Effect**
  * Prevents bronchial smooth muscle contraction
  * Decreases mucus production

Net effect:
  * Sustained bronchodilation

----

===== Clinical Role =====

Primary therapy:
  * COPD maintenance (first-line bronchodilator)

Adjunct therapy:
  * Asthma add-on therapy
  * Acute exacerbations (ipratropium + SABA)

Often combined with:
  * [[respiratory:beta2_agonists:start|β2 Agonists]]
  * [[respiratory:inhaled_corticosteroids:start|Inhaled Corticosteroids]]

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===== Onset and Duration =====

<WRAP center 80%>
^ Class ^ Onset ^ Duration ^ Clinical Role ^
| SAMA | ~15 min | ~6 hr | Exacerbation adjunct |
| LAMA | 30–60 min | 24+ hr | Maintenance therapy |
</WRAP>

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

^ Effect ^ Mechanism ^
| Dry mouth | Reduced secretions |
| Urinary retention | Bladder detrusor inhibition |
| Blurred vision | Ocular exposure |
| Constipation | GI smooth muscle inhibition |

Minimal systemic absorption due to inhaled route.

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===== Contraindications =====

  * Narrow-angle glaucoma (avoid eye exposure)
  * Urinary retention / BPH caution

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

<WRAP round tip 90%>
COPD is primarily cholinergic-mediated bronchoconstriction  
→ LAMA therapy is foundational treatment
</WRAP>

  * More effective in COPD than β2 agonists
  * Add ipratropium during exacerbations
  * Combine LAMA + LABA for maximal bronchodilation
  * Not anti-inflammatory drugs

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===== Comparison Within Bronchodilators =====

^ Drug Class ^ Mechanism ^ Best Disease Target ^
| β2 agonists | Stimulate dilation | Asthma |
| Antimuscarinics | Block constriction | COPD |

----

===== Related =====

  * [[autonomics:antimuscarinics|Autonomic Antimuscarinics]]
  * [[respiratory:beta2_agonists:start|β2 Agonists]]
  * [[respiratory:copd|COPD]]
  * [[respiratory:asthma|Asthma]]