Asthma drugs known as anticholinergics (muscarinic antagonists) inhibit acetylcholine-induced bronchoconstriction to help open narrowed airways. Short-acting anticholinergics (ipratropium bromide) provide add-on rescue relief during severe emergency room exacerbations, while long-acting anticholinergics (tiotropium) serve as maintenance add-on therapy for refractory asthma cases....