Blinding Is Seeing: A Single-Centre Study Into the Viability of Auto-Injectors for Blinded-Drug Administration in Randomised Controlled Trials

Objective The aim of the study was to assess the viability of auto-injector systems (A-INJ) for preserving investigator blinding in randomized controlled trials (RCT). Background Blinding refers to the concealment of group allocation from one or more individuals involved in a clinical research study. In the dosing of subcutaneous (SC) and intramuscular (IM) investigational medicinal products (IMP), specific challenges arise in maintaining investigator blinding. These challenges primarily involve the active injectate's viscosity and visual appearance (colour/translucency) in comparison to the placebo. Existing methods to control these issues are not perfect. Common approaches include using unblinded investigators or applying films or additives to make the active and placebo injectates appear similar. Method A single-centre experimental and descriptive study was carried out to compare the use of an A-INJ (Owen Mumford, Autoject 2) with the use of a conventional syringe (CS) in delivering a 1 ml dose of both placebo and reference IMP. The percentage delivery of the injectate was compared between the A-INJ IMP and placebo groups. Additionally, eight trained research physicians serving as investigators recorded their assessments of safety and effectiveness after performing serial injections with the A-INJ into a human-tissue analogue. Results Overall, a mean of 95.38% of 1ml placebo injectate was released from the A-INJ, compared to 96.00% from the CS. A total of 94.715% of 1 ml IMP injectate was released from the A-INJ, as opposed to 94.74% from the CS. Independent t-test analyses showed no statistical significance between the experimental arms. The mean administration time was 8.5 seconds. Investigators were unable to differentiate between the two solutions when using the A-INJ. There were no recorded concerns about investigators becoming unblinded, which stands in contrast to concerns associated with using the CS. Conclusion In assessing the viability of A-INJ use in RCTs, we noted a marked improvement when blinding was used. A-INJ systems effectively administer both placebo and active injectates, thereby maintaining the benefit of blinding without the need to alter the placebo through the addition of colourants or viscosity additives. While audio cues from the A-INJ and the time required to administer the injectate pose challenges, solutions are suggested. Although our findings are preliminary, they add to the existing literature on the advantages of A-INJs for administering injectable compounds and offer new perspectives on their utility in RCTs.