The primary difference between single-dose and multi-dose vials is that single-dose vials do not contain what?

Single-dose vials are specifically formulated to be used for a single patient and administration session, meaning they do not contain preservatives. The absence of preservatives is a crucial feature, as these vials are intended to hold medication that will be used immediately after opening. This design minimizes the risk of contamination, as any preservative would potentially allow for the bacteria to grow if the vial were stored for any length of time after its initial use.

In contrast, multi-dose vials contain preservatives to extend the shelf life of the medication and allow for multiple withdrawals of medication without significant risk of contamination. These preservatives are essential for ensuring the safety and efficacy of the medication over time.

The other options, such as additives, diluents, or pyrogens, do not fundamentally differentiate single-dose from multi-dose vials in the same manner as preservatives do. Additives may be present in both types of vials depending on the medication, while diluents are typically used to reconstitute medications but aren't specific to the number of doses in a vial. Pyrogens are unwanted contaminants, and both single and multi-dose vials must be free from them to ensure patient safety. Thus, it is the lack of preservatives that is the primary distinction between these two