Final answer:
A nurse invalidates the manufacturer's expiration date of insulin by not storing or handling it according to recommendations, such as exposing it to extreme temperatures or shaking it. Conditions like exposure to heat, sunlight, or freezing, can degrade insulin, making it ineffective before the expiration date.
Step-by-step explanation:
The action by the nurse that invalidates the manufacturer's expiration date of insulin includes exposing the insulin to extreme temperatures, both hot and cold, opening the insulin but not storing it as recommended, or not handling it as per the instructions. For instance, insulin typically needs to be stored in a refrigerator to maintain efficacy, but if it's left out at room temperature for an extended period, especially if it's above 86°F (30°C), the insulin can degrade and lose potency. Similarly, if insulin freezes, its chemical structure can be damaged. Exposing insulin to direct sunlight or heat sources also compromises its integrity. Improper handling, such as shaking the insulin vigorously, which is not recommended for certain types, can lead to insulin denaturation. All of these conditions can render the insulin less effective or even unusable before the expiration date that the manufacturer has set.