Theravance biopharma, a biopharmaceutical company primarily focused on the discovery and development of respiratory medicines, said that has started enrolment of patients for its phase 4 study of revefenacin (YUPLERI). The FDA had approved YUPLERI,  the first and only once-daily nebulized bronchodilator for the treatment of patients with COPD, for patient use sometime ago. The company said that the current trial is a randomized, double-blind, parallel-group study, comparing improvements in lung function in adults with severe to very severe COPD and suboptimal inspiratory flow rate following once-daily treatment over 12 weeks with either revefenacin inhalation solution delivered via standard jet nebulizer or tiotropium delivered via a dry powder inhaler.