Glass delamination is a phenomenon which can occur when top layers of a glass surface separate and flake off or detach from the inner surface, typically in the microscopic range. Glass delamination is the result of several factors, including the product formulation, the glass resistance and the glass manufacturing process itself. The formation of glass lamellae has a significant impact on product and patient safety. USP details the testing requirements for assessing the durability of glass container surfaces. The purpose of this presentation is to recommend “approaches to predict the potential of a drug product to cause formation of glass particles and delamination and to detect their occurrence.” These methods are not only applicable to the common vials encountered, but also to syringes, ampules and other glass containers that house drug products. USP describes the various types of glass encountered, how molded/tubing glass containers are manufactured and glass surface chemistry. After discussing the variables that affect the durability of the inner surface of glass containers, both predictive and aggressive screening suggestions are outlined. A common question that often arises is when to utilize USP in its entirety versus other protocols to simply identify the presence or absence of glass lamellae. Suggested methodologies may differ when selecting appropriate vials by a drug manufacturer versus identifying the presence or absence of glass delamination in a final product.
