A critical opinion-based review of hospital pharmacy compounding with respect to the risk of leachable substances due to the off-label use of plastic primary packaging.

Hospital pharmacies play a unique role in healthcare by regularly compounding drug products (DPs) in response to hospital demands and practices, for example, drug shortages, to cater to frail and vulnerable patients with infectious, chronic or nutrition-related conditions. Drugs are compounded in precise concentrations for extended durations, sometimes involving complex formulations. A significant challenge in this context is the off-label use of short-term plastic primary packaging for long-term storage of compounded DPs, which could be due to a lack of awareness, financial constraints and inadequate regulation. Without proper risk assessments, such packaging can release potentially harmful leachable compounds, posing a serious threat to patient safety. Evaluating hospital pharmacy compounding procedures to mitigate this risk is essential. While off-label drug use is a well-known concept in hospitals, off-label use of plastic primary packaging is an entirely different practice. In both the United States and Europe, healthcare professionals, including pharmacists, are allowed to use medical devices, including primary packaging, in ways that are not explicitly approved by regulators based on their clinical judgement and best practices, taking into account the patient's best interest. However, this off-label use could bring about unique risks and challenges, especially in the highly controlled environment of hospital pharmacy compounding, where patient safety is crucial. Therefore, the current review explores the historical context and the current landscape of hospital pharmacies, investigates the potential root causes of container closure integrity issues in pharmaceutical compounding, discusses the materials of construction as well as their physical-chemical properties influencing their roles in most popular primary packaging and finally presents expert opinions aimed at identifying long-term solutions to the existing challenges regarding their off-label uses in hospital pharmacy compounding.