What type of system prevents exposure of contents to air when opened?

A closed system is designed to prevent exposure of its contents to air when opened. This is particularly important in sterile compounding, where maintaining sterility is critical to prevent contamination. Closed systems are designed with integrity in mind, often using barriers or seals that maintain the environment inside without allowing outside air or contaminants to interact with the sterile materials.

In contrast, open systems do not provide this level of protection. They allow for the free exchange of air, which can expose the contents to potential contaminants and compromise sterility. Open containers similarly lack the protective seals found in closed systems, making them unsuitable for applications requiring strict sterility. Punctured systems, while potentially designed to minimize exposure, often still allow some air interaction when breached.

The effectiveness of closed systems in maintaining sterility and preventing contamination makes them the preferred choice in settings where the integrity of a product must be preserved.