A Study to Test Tetrandrine Tablets for Connective Tissue Disease-Related Lung Disease

This multicenter, randomized, double-blind, placebo-controlled study enrolls 100 adults with connective tissue disease-related interstitial lung disease. Patients are randomized 1:1 to receive tetrandrine tablets (60 mg TID) or placebo for 24 weeks, alongside standard treatment. The primary outcome is the change in forced vital capacity (FVC) at 24 weeks. Secondary outcomes include changes in serum inflammatory markers (TGF-β1, KL6, TNF-α, IL-6), lung HRCT scores, other Lung function parameters (TLC, VC, DLCO, PaO2), St. George's Respiratory Questionnaire (SGRQ) score, safety parameters, and all-cause mortality. Visits occur at weeks 4, 8, 12, and 24 for efficacy and safety assessments.

Inclusion criteria

• Patients who voluntarily participate and sign the informed consent form
• Male or female patients aged 18-80 years (inclusive)
• Patients meeting the diagnostic criteria for connective tissue disease-related interstitial lung disease per the 2018 Chinese Expert Consensus at screening
• FVC ≥40% of predicted value at screening
• Fertile male or female patients must agree to use effective contraception from signing informed consent until 3 months after the last study drug dose (Exemptions: postmenopausal women >50 years with amenorrhea for >1 year, or surgically sterilized women)
• Patients on stable doses of prednisone (≤20 mg/day or equivalent) or immunosuppressants for at least 4 weeks prior to study entry, with dose adjustments not exceeding this during the double-blind period

Exclusion criteria

• Treatment with tetrandrine or other antifibrotic drugs within 1 month before screening
• Diabetes with fasting blood glucose greater than 11.1 mmol per L
• Resting arterial oxygen partial pressure less than 50 mmHg
• Active peptic ulcers or bleeding disorders
• Tumors with expected survival less than 1 year
• Active pulmonary tuberculosis
• Alanine aminotransferase (ALT) or aspartate aminotransferase (AST) 5 times the upper limit of normal (ULN) or higher, or ALT or AST 3 times ULN or higher with total bilirubin 2 times ULN or higher
• Creatinine clearance less than 30 mL per min (per Cockcroft-Gault formula) or patients receiving dialysis
• Known allergy to tetrandrine or its excipients
• Severe psychological, mental, cognitive, or intellectual impairments that may affect compliance
• Pregnant or breastfeeding women, or those planning pregnancy within 3 months after the last study drug dose
• Participation in another clinical trial within 3 months before screening
• Patients deemed unsuitable for the study by the investigator
• Clinically significant environmental exposure history that may cause pulmonary fibrosis (e.g., amiodarone, asbestos, beryllium, radiation)