Concentrations of Intact Insulin Concurs With FDA and EMA Standards When Measured by HPLC in Different Parts of the Distribution Cold Chain

Thermal stability and storage of human insulin

BACKGROUND

Health authorities stress the temperature sensitivity of human insulin, advising protection from heat and freezing, with manufacturers suggesting low-temperature storage for intact vials, and once opened, storage at room temperature for four to six weeks, though usage time and maximum temperature recommendations vary. For human insulin, the recommendations of current shelf life in use may range from 10 to 45 days, and the maximum temperature in use varies between 25 °C and 37 °C. Optimal cold-chain management of human insulin from manufacturing until the point of delivery to people with diabetes should always be maintained, and people with diabetes and access to reliable refrigeration should follow manufacturers' recommendations. However, a growing segment of the diabetes-affected global population resides in challenging environments, confronting prolonged exposure to extreme heat due to the climate crisis, all while grappling with limited access to refrigeration.

OBJECTIVES

To analyse the effects of storing human insulin above or below the manufacturers' recommended insulin temperature storage range or advised usage time, or both, after dispensing human insulin to people with diabetes.

SEARCH METHODS

We used standard, extensive Cochrane search methods. The latest search date was 12 July 2023.

SELECTION CRITERIA

We included clinical and laboratory studies investigating the storage of human insulin above or below manufacturers' recommended temperature storage range, advised usage time, or both.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. We used GRADE to assess the certainty of evidence for the clinical study. Most information emerged from in vitro studies, mainly from pharmaceutical companies. There is no validated risk of bias and certainty of evidence rating for in vitro studies. We thus presented a narrative summary of the results.

MAIN RESULTS

We included 17 eligible studies (22 articles) and additional information from pharmaceutical companies. Pilot clinical study One pilot clinical study investigated temperature conditions for insulin stored for six weeks in an unglazed clay pot with temperatures ranging between 25 °C and 27 °C. The mean fall in plasma glucose in eight healthy volunteers after clay pot-stored insulin injection was comparable to refrigerator-stored insulin injection (very low-certainty evidence). In-vitro studies Nine, three and four laboratory studies investigated storage conditions for insulin vials, insulin cartridges/pens and prefilled plastic syringes, respectively. The included studies reported numerous methods, laboratory measurements and storage conditions. Three studies on prefilled syringes investigating insulin potency at 4 °C up to 23 °C for up to 28 days showed no clinically relevant loss of insulin activity. Nine studies examined unopened vials and cartridges. In studies with no clinically relevant loss of insulin activity for human short-acting insulin (SAI), intermediate-acting insulin (IAI) and mixed insulin (MI) temperatures ranged between 28.9 °C and 37 °C for up to four months. Two studies reported up to 18% loss of insulin activity after one week to 28 days at 37 °C. Four studies examined opened vials and cartridges at up to 37 °C for up to 12 weeks, indicating no clinically relevant reduction in insulin activity. Two studies analysed storage conditions for oscillating temperatures ranging between 25 °C and 37 °C for up to 12 weeks and observed no loss of insulin activity for SAI, IAI and MI. Four studies, two on vials (including one on opened vials), and two on prefilled syringes, investigated sterility and reported no microbial contamination. Data from pharmaceutical companies Four manufacturers (BIOTON, Eli Lilly and Company, Novo Nordisk and Sanofi) provided previously unreleased human insulin thermostability data mostly referring to unopened containers (vials, cartridges). We could not include the data from Sanofi because the company announced the permanent discontinuation of the production of human insulins Insuman Rapid, Basal and Comb 25. BIOTON provided data on SAI after one, three and six months at 25 °C: all investigated parameters were within reference values, and, compared to baseline, loss of insulin activity was 1.1%, 1.0% and 1.7%, respectively. Eli Lilly and Company provided summary data: at below 25 °C or 30 °C SAI/IAI/MI could be stored for up to 25 days or 12 days, respectively. Thereafter, patient in-use was possible for up to 28 days. Novo Nordisk provided extensive data: compared to baseline, after three and six months at 25 °C, loss of SAI activity was 1.8% and 3.2% to 3.5%, respectively. Loss of IAI activity was 1.2% to 1.9% after three months and 2.0% to 2.3% after six months. Compared to baseline, after one, two and three months at 37 °C, loss of SAI activity was 2.2% to 2.8%, 5.7% and 8.3% to 8.6%, respectively. Loss IAI activity was 1.4% to 1.8%, 3.0% to 3.8% and 4.7% to 5.3%, respectively. There was no relevant increase in insulin degradation products observed. Up to six months at 25 °C and up to two months at 37 °C high molecular weight proteins were within specifications. Appearance, visible particles or macroscopy, particulate matter, zinc, pH, metacresol and phenol complied with specifications. There were no data for cold environmental conditions and insulin pumps.

AUTHORS' CONCLUSIONS

Under difficult living conditions, pharmaceutical companies' data indicate that it is possible to store unopened SAI and IAI vials and cartridges at up to 25 °C for a maximum of six months and at up to 37 °C for a maximum of two months without a clinically relevant loss of insulin potency. Also, oscillating temperatures between 25 °C and 37 °C for up to three months result in no loss of insulin activity for SAI, IAI and MI. In addition, ambient temperature can be lowered by use of simple cooling devices such as clay pots for insulin storage. Clinical studies on opened and unopened insulin containers should be performed to measure insulin potency and stability after varying storage conditions. Furthermore, more data are needed on MI, insulin pumps, sterility and cold climate conditions.

Regulatory Verification by Health Canada of Content in Recombinant Human Insulin, Human Insulin Analog, and Porcine Insulin Drug Products in the Canadian Market Using Validated Pharmacopoeial Methods Over Nonvalidated Approaches

BACKGROUND

For diabetes mellitus treatment plans, the consistency and quality of insulin drug products are crucial for patient well-being. Because biologic drugs, such as insulin, are complex heterogeneous products, the methods for drug product evaluation should be carefully validated for use. As such, these criteria are rigorously evaluated and monitored by national authorities. Consequently, reports that describe significantly lower insulin content than their label claims are a concern. This issue was raised by a past publication analyzing insulin drug products available in Canada, and, as a result, consumers and major patient organizations have requested clarification.

METHODS

To address these concerns, this study independently analyzed insulin drug products purchased from local Canadian pharmacies-including human insulin, insulin analogs, and porcine insulin-by compendial and noncompendial reversed-phase high-performance liquid chromatography (RP-HPLC) methods.

RESULTS

We demonstrated the importance of using methods fit for purpose when assessing insulin quality. In a preliminary screen, the expected insulin peak was seen in all products except two insulin analogs-insulin detemir and insulin degludec. Further investigation showed that this was not caused by low insulin content but insufficient solvent conditions, which demonstrated the necessity for methods to be adequately validated for product-specific use. When drug products were appropriately assessed for content using the validated type-specific compendial RP-HPLC methods for insulin quantitation, values agreed with the label claim content.

CONCLUSIONS

Because insulin drug products are used daily by over a million Canadians, it is important that researchers and journals present data using methods fit for purpose and that readers evaluate such reports critically.

Assessment of Regular and NPH Insulin Concentration via Two Methods of Quantification: The Washington State Insulin Concentration Study (WICS)

BACKGROUND

Recent reports have suggested that insulin vials purchased in community pharmacies do not meet the minimum required intact insulin concentration (≥95 U/mL) as defined by the United States Pharmacopeia. We sought to independently obtain multidose human insulin vials from a variety of community pharmacies across the state of Washington and quantitatively measure intact insulin.

METHODS

Sixty 10-mL vials of insulin (n = 30 regular human insulin and n = 30 neutral protamine Hagedorn insulin) were purchased and assayed. To ensure random selection of lots and supply chain sources, insulin samples were purchased on a variety of calendar dates from various pharmacy locations across Washington State, inclusive of both chain and independent pharmacies. All samples were assessed for intact insulin concentration via both Ultra Performance Liquid Chromatography coupled with UV detection (UPLC-UV) and Ultra Performance Liquid Chromatography-Mass Spectrometry (UPLC-MS).

RESULTS

When considering all samples (N = 60), the mean concentration was 101.8 ± 4.4and 91.5 ± 1.9 U/mL as determined by UPLC-UV and UPLC-MS, respectively. Measured concentrations ranged from 90.0 to 108.4 U/mL when assayed by UV UPLC and 86.1 to 95.4 U/mL for UPLC-MS.

CONCLUSION

To our knowledge, this is the first study following the report by Carter et al that assessed human insulin concentrations by both UPLC-UV and UPLC-MS. These findings are important because they demonstrate that the results obtained from these two methods differ and that the method used must be considered when interpreting findings.

Insulin Storage: A Critical Reappraisal

Insulin, as a peptide hormone drug, is susceptible to changes in stability when exposed to environmental factors under storage. Proper storage according to the manufacturer's recommendations is important to maintain its potency and enable precise dosing for people with diabetes (PwD). While it is reasonable to assume that transport conditions and temperature are well controlled during the supply chain, little is known about insulin storage after dispensing and insulin potency at the moment of administration. Insulin is exposed to various environmental factors when carried by PwD and storage recommendations are often not met when it is stored in household refrigerators. It is difficult to assess changes in insulin potency in clinical practice, and there is a gap in the current scientific literature on insulin stability. Package leaflet recommendations only give limited information on the impact of improper storage conditions on insulin stability and guidelines by health organizations are inconsistent. Given the importance of precise dosing in diabetes care, there is a need for more transparency on insulin stability, awareness for proper storage among health care professionals and PwD as well as clear guidelines and practical storage recommendations from manufacturers and health organizations.

Commercially Available Insulin Products Demonstrate Stability Throughout the Cold Supply Chain Across the U.S

OBJECTIVE

A recent publication questioned the integrity of insulin purchased from U.S. retail pharmacies. We sought to independently validate the method used, isotope dilution solid-phase extraction (SPE) liquid chromatography mass spectrometry (LC-MS), and expand analysis to two U.S. Pharmacopeia (USP) methods (high-performance LC with ultraviolet detection and LC-MS).

RESEARCH DESIGN AND METHODS

Each method was used to evaluate nine insulin formulations, purchased at four pharmacies, within five geographic locations in the U.S.

RESULTS

All human and analog insulins measured by the USP methods (n = 174) contained the expected quantity of active insulin (100 ± 5 units/mL). When using isotope dilution SPE-LC-MS, units-per-milliliter values were well below product labeling due to unequal recovery of the internal standard compared with target insulin.

CONCLUSIONS

Insulin purchased from U.S. pharmacies is consistent with product labeling.

Concentration and Chemical Stability of Commercially Available Insulins: A High-Resolution Mass Spectrometry Study

Adequacy of insulin concentration in commercially available insulin formulations has recently been challenged. We therefore repeatedly evaluated insulin content and stability of 58 insulin vials containing 5 different insulin formulations (human insulin, standard/faster-acting insulin aspart, insulin lispro, and insulin glargine) over a period of 85 days. High-resolution mass spectrometry was used to quantify intact monomeric insulin in glass vials and plastic pump cartridges exposed to three different temperatures (4°C, 22°C, 37°C), simulating real-life conditions. In all cases, measured insulin concentration was in accordance with FDA and European Medicines Agency (EMA) requirements without evidence of chemical instability.

NMR Spectroscopic Analysis to Evaluate the Quality of Insulin: Concentration, Variability, and Excipient Content

Known and consistent bioactivity between samples of insulin is essential to correctly estimate the dose. Insulin concentration is not the same thing as bioactivity, however, and methods to correctly determine both are required. Here we show that one dimensional nuclear magnetic resonance (1D NMR), in contrast to, for example, reverse phase high pressure liquid chromatography, can be used to determine both insulin concentration as well as confirm the structural integrity required for activity. In response to the report by Carter and Heinemann, we decided to investigate insulin intended for public use. Insulin from several manufacturers was investigated. Correct insulin concentrations were found in all tested samples although the general sample variability, which possibly could influence the bioactivity, varied depending on insulin type and manufacturer.

The Effect of Temperature on the Stability of In-Use Insulin Pens

BACKGROUND

Improper storage of insulin could decrease its potency. Manufacturers recommend that in-use insulin pens should be kept at between 25-30°C, but room temperature in tropical countries often exceeds this range. This study investigates the effect of temperature on the stability of basal insulin in cartridges 28 days after opening.

METHODS

Four different basal insulins were evaluated. Five opened pens of each insulin type were included for each of three storage conditions and 5 unopened insulin pens of each type were stored in the refrigerator as a control. The opened pens were stored for 28 days in either a refrigerator (2-8 °C), at room temperature, or in an incubator (37 °C). Each day insulin pens were mixed 20 times and 2 units were discarded to mimic daily usage. Insulin quantity was evaluated using an ultra-high-performance liquid chromatography assay.

RESULTS

The average room temperature during the study period was 29.7 °C. After 28 days, the percentage amount of insulin stored at refrigerator, room temperature or incubator, compared with control was 99.0, 99.7, 101.1% for long-acting insulin; 97.4, 97.2, 99.0% for NPH-1; 101.4, 101.5, 100.7% for NPH-2; and 98.7, 97.8, 98.5% for NPH-3. There were no statistically significant differences. However, we observed a trend toward different stability between clear insulin analog and turbid NPH insulin.

CONCLUSIONS

Temperature as high as 37°C and cyclic temperature,had no effect on the stability of in-use insulin pen.