From the Guidelines
Spiriva (tiotropium) works as a long-acting anticholinergic bronchodilator by selectively blocking muscarinic receptors in the airways, specifically binding to M3 muscarinic receptors on airway smooth muscle, preventing acetylcholine from binding to these receptors. This mechanism of action results in reduced bronchial smooth muscle contraction, leading to bronchodilation that lasts approximately 24 hours 1. The medication is typically administered as an inhaled powder (18 mcg once daily) via the HandiHaler device or as a soft mist inhaler (Respimat, 2.5 mcg, two inhalations once daily). By reducing airway constriction, Spiriva improves airflow, reduces air trapping, and decreases breathlessness in patients with chronic obstructive pulmonary disease (COPD) or asthma. Some key points to consider about Spiriva's mechanism of action and its effects include:
- Tiotropium has a slow dissociation rate from M3 receptors, which explains its long duration of action 1.
- Unlike short-acting bronchodilators, Spiriva is not intended for immediate relief of acute bronchospasm but rather for maintenance therapy to provide sustained bronchodilation throughout the day.
- Long-acting muscarinic antagonists (LAMAs) like tiotropium have been shown to have a greater effect on exacerbation reduction compared to long-acting β-agonists (LABAs) and decrease hospitalizations 1. Overall, Spiriva's mechanism of action as a long-acting anticholinergic bronchodilator makes it an effective treatment option for patients with COPD or asthma, improving symptoms and reducing the risk of exacerbations.
From the FDA Drug Label
Tiotropium is a long-acting, muscarinic antagonist which is often referred to as an anticholinergic. It has similar affinity to the subtypes of muscarinic receptors, M1 to M5. In the airways, it exhibits pharmacological effects through inhibition of M3-receptors at the smooth muscle leading to bronchodilation
The mechanism of action for Spiriva (tiotropium) is through inhibition of M3-receptors at the smooth muscle, leading to bronchodilation. Tiotropium is a long-acting, muscarinic antagonist, also referred to as an anticholinergic. It has a similar affinity to the subtypes of muscarinic receptors, M1 to M5. 2
From the Research
Mechanism of Action of Spiriva
The mechanism of action of Spiriva (tiotropium) involves the antagonism of muscarinic receptors in the airway smooth muscle, specifically the M1, M2, and M3 receptors 3, 4, 5, 6, 7.
- Tiotropium bromide is a quaternary ammonium derivative that binds to these receptors, causing a long-lasting bronchodilation effect.
- The kinetic selectivity of tiotropium for M1 and M3 receptors over M2 receptors allows for a sustained bronchodilator effect without significant tachyphylaxis 3, 4.
- The drug works by reversing vagally mediated bronchoconstriction, resulting in improved lung function, dyspnea, and health-related quality of life in patients with chronic obstructive pulmonary disease (COPD) 3, 4, 5, 6, 7.
Key Features of Tiotropium
Some key features of tiotropium include:
- Long-acting anticholinergic bronchodilator effect, lasting at least 24 hours 3, 4, 6.
- Once-daily dosing, allowing for convenient administration and improved patient compliance 3, 4, 5, 6, 7.
- Selective antagonist of pulmonary M1 and M3 muscarinic receptor subtypes, resulting in a targeted therapeutic effect 4, 5, 7.
- Improved lung function, symptom control, and quality of life in patients with COPD, as well as reduced frequency of exacerbations and hospitalizations 3, 4, 5, 6, 7.