Open-Label Study
A clinical trial where both participants and researchers know which treatment is being given. Open-label designs are used when blinding is impractical or in long-term extension studies where participants continue on active treatment after completing a blinded trial.
Technical Context
Open-label designs are used when: blinding is technically impossible (e.g. comparing injectable vs oral formulations), the study is primarily assessing safety rather than efficacy, in compassionate use settings, or for Phase I dose-finding where investigators need to observe real-time effects. Open-label extension studies are the most common application in peptide drug development — participants who completed a blinded trial continue on active treatment for 1-5+ years, providing long-term safety data (adverse events, immunogenicity, laboratory parameters) and durability of efficacy data. Open-label extension data for GLP-1 RAs have demonstrated sustained weight loss and glycaemic control over 2-4+ years of continuous treatment.