Double-Blind

A double-blind study is an experimental design in which neither the research participants nor the investigators administering the treatment or assessing outcomes know which subjects are receiving the active compound and which are receiving the placebo or comparator. This dual blinding eliminates both participant expectation bias and investigator assessment bias, providing the most rigorous framework for evaluating true treatment effects. The randomisation code is typically held by an independent data safety monitoring board and is only unblinded after data collection is complete or in case of serious safety concerns. Double-blinding is considered the gold standard for phase II and phase III clinical trials and is essential for regulatory submissions to agencies such as the FDA and EMA. In peptide research, maintaining double-blind conditions can be challenging when active compounds produce detectable physiological effects such as injection-site reactions or characteristic side effects that may inadvertently unblind participants or investigators, a phenomenon known as functional unblinding.