What characteristic of an ampule limits its use after opening?

An ampule is designed for single-use, meaning that once it is opened, the contents must be used immediately and cannot be stored for later use. This characteristic is essential for maintaining the sterility and integrity of the medication inside. After breaking the neck of an ampule, exposure to air and potential contaminants occurs, making it unsafe to use again.

Using an opened ampule later could lead to significant risks, such as contamination or degradation of the medication, which could compromise patient safety. Once opened, the contents should either be used right away or discarded to ensure that the administration of the medication is effective and safe for the patient. This single-use nature is a fundamental guideline in sterile compounding practices.