Efficacy of liriope platyphylla extract for improving respiratory functions: Study protocol for a randomized, double-blinded, placebo-controlled pilot trial.

ABSTRACT

BACKGROUND: Respiratory disease has emerged as a global issue due to COVID-19. In particular, there has been an increased frequency of occurrence of symptoms such as cough, sputum, and dyspnea, which commonly accompany chronic obstructive pulmonary disease (COPD). Liriope platyphylla (LP) extract is known to improve respiratory function. LP extract ameliorates the symptoms commonly seen in bronchitis, asthma, and COPD and enhances immunity, as it has anti-inflammatory properties. In a previous study in rats, LP effectively improved respiratory inflammation levels. However, few randomized controlled trials have verified the effects of LP in respiratory disease and there have been no studies to determine the appropriate dose and duration to make it a more convenient functional health product. Based on previous studies, we would like to proceed with this clinical trial under the assumption that LP will help improve respiratory function and produce anti-inflammatory effects. METHODS: This will be a single-center, randomized, double-blind, placebo-controlled pilot trial. Participants will randomly be allocated to receive either 1000 mg LP or placebo. The total duration of the clinical trial will be 4 to 6 weeks. A follow-up assessment will be conducted 4 weeks after screening, and the effect and safety of LP application will be assessed at this second visit. The primary outcome will be the breathlessness, cough, and sputum scale score. Secondary outcomes will include pulmonary function, clinical symptoms of cough and sputum (reported through a questionnaire), changes in immune cells, changes in immune factors used to analyze allergic inflammation in bronchi, antioxidant enzyme activity, nitric oxide level, and COPD assessment test score. DISCUSSION: This study has limited inclusion and exclusion criteria and the intervention will be well-controlled. This will be the first randomized controlled trial to assess the efficacy and safety of LP extract in adults with cough and sputum. This study will provide insight into the mechanisms of the anti-inflammatory effects and improvement of respiratory function of LP.