Effect of Silymarin as Add on Therapy on Oxidative Stress, Pulmonary Function and Quality of Life in Stable COPD Patients; A Randomized Double-Blind Placebo-Controlled Trial

Chronic Obstructive Pulmonary Disease (COPD) is a leading cause of morbidity and mortality worldwide, characterized by persistent airflow limitation and an exaggerated inflammatory response. Oxidative stress plays a pivotal role in disease progression, contributing to worsening pulmonary function, increased exacerbations, and poor quality of life. Current pharmacological interventions, including inhaled corticosteroids (ICS), bronchodilators, and mucolytics (e.g., acetylcysteine, carbocysteine, erdosteine), have limitations such as increased risk of infections, systemic side effects, and suboptimal long-term efficacy in mitigating oxidative stress. Antioxidant vitamins (A, C, E) have been explored for oxidative stress management but demonstrate inconsistent clinical benefits.

Silymarin, a bioflavonoid complex derived from Silybum marianum, possesses potent antioxidant, anti-inflammatory, and hepatoprotective properties. Silymarin is safe in human at therapeutic doses and is well tolerated even at high dose of 700 mg three times a day for 24 weeks. It scavenges reactive oxygen species (ROS), upregulates endogenous antioxidant defense mechanisms, and modulates inflammatory pathways, making it a promising candidate for managing oxidative stress in COPD. Despite extensive use in hepatic disorders, its therapeutic potential in pulmonary diseases remains underexplored.

Aim: This study aims to evaluate the effect of Silymarin on oxidative stress, pulmonary function, and quality of life in stable COPD patients.

Methodology: This research will be conducted in Pharmacology department of Bangabandhu Sheikh Mujib Medical University (BSMMU) and outpatient department of Respiratory Medicine of BSMMU from the day of approval by IRB to January, 2026. It will be single centered, randomized, double-blind, placebo-controlled trial involving stable COPD patients receiving 'Indacaterol plus Glycopyrronium'. 70 Participants will be enrolled, 35 in each group, randomly assigned to receive either Silymarin 140 mg thrice daily or placebo thrice daily for 12 weeks period. The primary outcome will be changes in oxidative stress markers (e.g., malondialdehyde, erythrocyte glutathione). Secondary outcomes include pulmonary function test (FEV1), quality of life (SGRQ-C scores). Data will be collected about various socio-demographic variables such as age, sex, smoking history, other co-morbidities. Silymarin 140 mg capsule and placebo will be purchased from Square Pharmaceutical Limited. We have an initial discussion and have a commitment that they will provide medicine and placebo along with quality control certificate. Descriptive statistics will be used for demographic variables. Means and standard deviation for continuous variables and number, percentage for categorical variables will be used. For independent samples; t-test will be utilized to analyze the average differences in MDA conc., erythrocyte glutathione conc. between the group receiving Silymarin supplement and the group receiving placebo. The Chi-square test will be employed to compare the percentage of participants may show a significant change in MDA, erythrocyte glutathione conc. in the group that received Silymarin versus the group that received placebo. Pearson or Spearman correlation tests will be used to explore any relationships between baseline MDA, erythrocyte glutathione conc. and baseline FEV1, SGRQ-C score as well as change among in MDA, erythrocyte glutathione conc. and the change in FEV1, SGRQ-C score. This study will adhere to ethical guidelines for human research, ensuring informed consent, patient safety, and data confidentiality.

Conclusion: Given the limitations of current antioxidant therapies in COPD, Silymarin offers a novel, potentially safer approach to mitigating oxidative stress and improving patient outcomes. If effective, it could serve as an adjunctive therapy to conventional COPD management, reducing the reliance on ICS and mucolytics while addressing the underlying pathophysiology of the disease and mitigating disease progression.