A Study to Evaluate the Preliminary Efficacy and Safety of Terfenadine in Patients With Relapsing-Remitting Multiple Sclerosis

Multiple sclerosis (MS) is a chronic immune-mediated disease of the central nervous system that can cause neurological disability and disease progression. Current disease-modifying therapies can reduce relapses and MRI disease activity, but limitations remain in preventing disability progression and promoting remyelination or neuroprotection. Terfenadine is a histamine H1 receptor antagonist. Preclinical evidence suggests that histamine signaling may be involved in immune and inflammatory processes relevant to MS. This study will evaluate the safety and tolerability of terfenadine as an adjunct to standard first-line disease-modifying therapy and explore its potential clinical effects in people with MS. This is a single-center, open-label, randomized controlled clinical trial. Approximately 100 participants will be enrolled and randomly assigned in a 2:1 ratio to a terfenadine treatment group or a control group. Participants in the terfenadine group will receive terfenadine 60 mg orally once daily at bedtime for 1 month in addition to standard first-line disease-modifying therapy. Participants in the control group will receive standard first-line disease-modifying therapy alone. Participants will be followed for 12 months. Study assessments will include physical examinations, vital signs, laboratory tests, electrocardiograms, imaging examinations, neurological and functional assessments, quality-of-life assessments, and collection of blood, stool, and cerebrospinal fluid samples at scheduled visits. Safety will be assessed throughout the study by recording and following adverse events and by reviewing relevant clinical and laboratory findings.