NPH insulin is an intermediate-acting insulin used to help manage blood sugar levels in individuals with diabetes.
Storing Unopened NPH Insulin
Unopened NPH insulin vials, pens, or cartridges require refrigeration until their expiration date. The recommended storage temperature range for unopened insulin is typically between 36°F and 46°F (2°C and 8°C). Keep unopened insulin in the main compartment of the refrigerator, rather than the door, to minimize exposure to temperature fluctuations. Protection from direct light and freezing temperatures is necessary, as both can degrade the insulin.
Storing Opened NPH Insulin
Once an NPH insulin vial or pen has been opened, storage requirements change. Opened NPH insulin can generally be kept at room temperature, typically ranging from 59°F to 86°F (15°C to 30°C). This allows for more comfortable injections, as cold insulin can sometimes cause discomfort. The duration for which opened NPH insulin can be used at room temperature varies by manufacturer, but it is commonly between 14 and 28 days. For instance, some NPH products like Humulin N pens might be used for up to 14 days, while Novolin N can extend to 28 days.
Check the specific product’s insert for precise manufacturer recommendations. Discarding the insulin after the specified period, even if some remains, is important because its effectiveness may diminish, potentially leading to inadequate blood sugar control. Insulin should be kept away from direct heat and sunlight during this period.
Identifying Damaged Insulin
NPH insulin appears as a cloudy, white suspension. Before each use, it should be gently rolled between the palms to ensure the contents are uniformly mixed and cloudy.
Several visual cues indicate that NPH insulin may have been compromised. These signs include the presence of clumps, granules, or solid particles that do not disperse after gentle mixing. A frosted appearance on the inside of the vial or pen, a clear appearance when it should be cloudy, or any discoloration also suggest spoilage. If the insulin has been frozen, it should not be used, as freezing can irreversibly affect its structure. Using insulin that shows any of these signs of degradation can lead to unpredictable effects on blood sugar levels.
The Importance of Correct Storage
Insulin is a protein-based medication, making it sensitive to environmental factors like extreme temperatures and light exposure. When insulin is exposed to temperatures that are too hot or too cold, or to direct sunlight, its protein structure can degrade. This degradation reduces the insulin’s effectiveness.
Using degraded insulin can result in hyperglycemia because the medication is not providing the expected therapeutic effect. Consistent and accurate blood sugar control is important for individuals with diabetes, and compromised insulin can disrupt this balance, potentially leading to health complications. Proper storage helps ensure that each dose of NPH insulin delivers its full intended potency, supporting stable blood sugar levels and overall health.