Oxitropium bromide is an mAChR antagonist used as an anticholinergic bronchodilator drug for the treatment of asthma and chronic obstructive pulmonary disease.
Oxitropium bromide is a muscarinic antagonist which blocks musucarinic acetylcholine receptors (mAChR). Incubation with oxitropium bromide of untreated diaphragm muscle and diaphragm muscle injected with endotoxin does not increase the force-frequency curves dose-dependently in vitro; however, it causes both types of muscle to be fatigue resistant[1].
Oxitropium bromide inhalation shifts force-frequency curves upward at 2 h after inhalation and inhibits the decrease of force-frequency curves due to endotoxin injection in vivo[1]. Oxitropium bromide strongly and persistently inhibits the acetylcholine (ACh)-induced resistance. The increase in resistance induced by histamine, serotonin, leukotriene D4 or antigen is prevented by oxitropium bromide oxitropium bromide[2]. Inhalation of the anticholinergic agent oxitropium bromide at doses of 1.5 μg and higher greatly attenuates the decrease in mucus score produced by intravenous histamine but not by inhaled histamine[3].
[1]. Shindoh C, et al. Effects of inhalation or incubation of oxitropium bromide on diaphragm muscle contractility in mice. Allergol Int. 2011 Sep;60(3):365-72. [2]. Kohno SW, et al. Effect of oxitropium bromide (Ba253) on increased airway resistance induced by various agonists and antigen in the guinea pig. Jpn J Pharmacol. 1989 Aug;50(4):455-66. [3]. Takeyama K, et al. Effect of oxitropium bromide on histamine-induced airway goblet cell secretion. Am J Respir Crit Care Med. 1996 Jul;154(1):231-6.