Sepracor in the US is developing arformoterol [R,R-formoterol], a single isomer form of the β2-adrenoceptor agonist formoterol [eformoterol]. This isomer contains two chiral centres and is being developed as an inhaled preparation for the treatment of respiratory disorders. Sepracor believes that arformoterol has the potential to be a once-daily therapy with a rapid onset of action and a duration of effect exceeding 12 hours.In 1995, Sepracor acquired New England Pharmaceuticals, a manufacturer of metered-dose and dry powder inhalers, for the purpose of preparing formulations of levosalbutamol and arformoterol.Phase II dose-ranging clinical studies of arformoterol as a longer-acting, complementary bronchodilator were completed successfully in the fourth quarter of 2000. Phase III trials of arformoterol began in September 2001. The indications for the drug appeared to be asthma and chronic obstructive pulmonary disease (COPD). However, an update of the pharmaceutical product information on the Sepracor website in September 2003 listed COPD maintenance therapy as the only indication for arformoterol.In October 2002, Sepracor stated that two pivotal phase III studies were ongoing in 1600 patients. Sepracor estimates that its NDA submission for arformoterol, which is projected for the first half of 2004, will include approximately 3000 adult subjects.Sepracor stated in July 2003 that it had completed more than 100 preclinical studies and initiated or completed 15 clinical studies for arformoterol inhalation solution for the treatment of bronchospasm in patients with COPD. In addition, Sepracor stated that the two pivotal phase III studies in 1600 patients were still progressing.In 1995, European patents were granted to Sepracor for the use of arformoterol in the treatment of asthma, and the US patent application was pending.