Pain Induced by m-Cresol as Preservative

Preservatives such as m-Cresol are essential components in many subcutaneously injected medications, including insulin or human growth hormone, to prevent bacterial growth. However, clinical reports have suggested that these preservatives may cause local discomfort or pain at the injection site, which can negatively impact treatment adherence. While m-Cresol is widely used, its direct contribution to injection-site pain has not yet been investigated in a prospective clinical trial. This study aims to investigate whether subcutaneous injection of m-Cresol at concentrations commonly used in clinical practice (0.1% and 0.25%) cause significantly more pain than a preservative-free control solution. In a randomized, double-blind crossover design, healthy volunteers will receive three separate injections in a belly fold. Participants will rate their pain every 5 seconds until it subsides. The findings will help determine if m-Cresol is a primary source of injection-site pain and could lead to the development of more comfortable drug formulations.