Tiotropium bromide

Tiotropium bromide, sold under the brand name Spiriva among others, is a long-acting bronchodilator (LAMA: long acting muscarinic antagonist) used in the management of chronic obstructive pulmonary disease (COPD) and asthma.^[1][2] Specifically it is used during periods of breathing difficulty to prevent them from getting worse, rather than to prevent them from happening.^[1] See also Tiotropium bromide.

Tiotropium is a muscarinic receptor antagonist, often referred to as an antimuscarinic or anticholinergic agent. Although it does not display selectivity for specific muscarinic receptors, when topically applied it acts mainly on M3 muscarinic receptors^[3] located on smooth muscle cells and submucosal glands. This leads to a reduction in smooth muscle contraction and mucus secretion and thus produces a bronchodilatory effect.

M3 muscarinic acetylcholine receptor bound to the antagonist tiotropium (4u14).

Tiotropium binding site.