Dose accuracy and durability of a durable insulin pen before and after simulated lifetime use

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.

Precision Dosing of Rapid-Acting Insulin Matters

Despite several molecular and technological advances in insulin therapy and insulin delivery, global evidence highlights inadequate glycemic control in populations with type 1 diabetes (T1D) and type 2 diabetes (T2D). In this review, we discuss the importance of more precise dosing of insulin as one of the approaches to improve glycemic control while reducing hypoglycemic events. This report is based on the expert opinion of authors and literature search of articles relevant to the past and present insulin delivery devices in diabetes management, especially half-unit insulin pens. We describe the various factors that facilitate better glycemic control, focusing on the impact of appropriate insulin delivery device selection on diabetes management. Precision dosing of insulin is a lesser-studied factor that contributes toward better glycemic control. Insulin pens have consistently outperformed syringes as delivery devices due to their greater accuracy and precision of dosing, ease-of-use, and patient preference. These advantages make them better suited to administer insulin in hypoglycemia-prone insulin-sensitive people with T1D, particularly younger children and geriatric patients. Half-unit insulin pens further extend this benefit by delivering half-unit doses of insulin accurately. They may contribute to better management of diabetes by allowing flexible dosing for mealtimes and physical activities even in erratic diet situations or illnesses by offering corrective doses in small increments. They are ideal delivery devices for insulin-sensitive people with T1D who require greater accuracy and precision in insulin delivery to achieve more stringent glycemic control.

Insulin-delivery methods for children and adolescents with type 1 diabetes

Efforts directed toward restoring normal metabolic levels by mimicking the physiological insulin secretion, thereby ensuring safety, efficacy, minimal invasiveness and conveniences, are of great significance in the management of type 1 diabetes among children and adolescents. Regardless of the various technologies being discovered in addressing invasiveness and enhancing medication adherence in the management of type 1 diabetes, yet limited success had been observed among children and adolescents. The multiple daily subcutaneous insulin injections route using vial and syringe, and occasionally insulin pens, remain the most predictable route for insulin administration among children and adolescents. However, this route has been associated with compromised patient compliance, fear of injections and unacceptability, resulting in poor glycemic control, which promote the demand for alternative routes of insulin administration. Alternative routes for delivering insulin are being investigated in children and adolescents with type 1 diabetes; these include the hybrid closed-loop 'artificial pancreas' system, oral, inhalation, intranasal routes, and others. This review article explores the current advances in insulin-delivery methods that address the needs of children and adolescents in the treatment of type 1 diabetes.

Dose Accuracy, Injection Force, and Usability Assessment of a New Half-Unit, Prefilled Insulin Pen

BACKGROUND

This study examines the utility of the first prefilled, rapid-acting insulin pen that can be dialed in half-unit increments. Dose accuracy and injection force were examined through a series of design-verification tests, and usability was established by human factors validation testing.

METHODS

Devices were tested for dose accuracy at 3 different doses and temperatures and under free fall, vibration, and cold storage conditioning. Injection force was measured at the maximum dose (30 units). Both experiments used the same semiautomated testing system. Usability was validated in a human factors simulated-use study that included 60 participants (patients with type 1 or type 2 diabetes [aged 10-79 years], adult caregivers, and health care providers).

RESULTS

The pen met the International Organization for Standardization (ISO) 11608-1:2014 requirements for dose accuracy at all settings and conditions tested. Furthermore, all individual results were within the ISO specification limits. Mean injection force across temperature settings ranged from 9.25 to 10.85 N at the highest dose. The usability validation study confirmed that use-related risks were reduced to the extent possible and that additional modifications were not likely to afford further reductions.

CONCLUSIONS

The results from these studies demonstrated accurate dosing over the dose range (0.5-30 units) at different temperatures and conditions with an injection force that should accommodate the intended users. Use safety and usability in patients with diabetes, caregivers, and health care professionals were validated. The added convenience of this new half-unit, prefilled pen may ease the burden of diabetes management for patients who require smaller incremental dosing.

Half-Unit Insulin Pens: Disease Management in Patients With Diabetes Who Are Sensitive to Insulin

BACKGROUND

Insulin pens represent a significant technological advancement in diabetes management. While the vast majority have been designed with 1U-dosing increments, improved accuracy and precision facilitated by half-unit increments may be particularly significant in specific patients who are sensitive to insulin. These include patients with low insulin requirements and in those requiring more precise dose adjustments, such as the pediatric patient population. This review summarized functional characteristics of insulin half-unit pens (HUPs) and their effect on user experience.

METHODS

The literature search was restricted to articles published in English between January 1, 2000, and January 1, 2015. A total of 17 publications met the set criteria and were included in the review.

RESULTS

Overall, studies outlined characteristics for 4 insulin HUPs. Based on their functionality, the pens were generally similar and all met the ISO 11608-1 criteria for accuracy. However, some had specific advantageous features in terms of size, weight, design, dialing torque, and injection force. Although limited, the currently available user preference studies in children and adolescents with diabetes and their carers suggest that the selection of an HUP is likely to be influenced by a combination of factors such as these, in addition to the prescribed insulin and dosing regimen.

CONCLUSIONS

Insulin HUPs are likely to be a key diabetes management tool for patients who are sensitive to insulin; specific pen features may further advance diabetes management in these populations.

NovoPen Echo(®) insulin delivery device

The introduction of insulin pen devices has provided easier, well-tolerated, and more convenient treatment regimens for patients with diabetes mellitus. When compared with vial and syringe regimens, insulin pens offer a greater clinical efficacy, improved quality of life, and increased dosing accuracy, particularly at low doses. The portable and discreet nature of pen devices reduces the burden on the patient, facilitates adherence, and subsequently contributes to the improvement in glycemic control. NovoPen Echo^® is one of the latest members of the NovoPen^® family that has been specifically designed for the pediatric population and is the first to combine half-unit increment (=0.5 U of insulin) dosing with a simple memory function. The half-unit increment dosing amendments and accurate injection of 0.5 U of insulin are particularly beneficial for children (and insulin-sensitive adults/elders), who often require small insulin doses. The memory function can be used to record the time and amount of the last dose, reducing the fear of double dosing or missing a dose. The memory function also provides parents with extra confidence and security that their child is taking insulin at the correct doses and times. NovoPen Echo is a lightweight, durable insulin delivery pen; it is available in two different colors, which may help to distinguish between different types of insulin, providing more confidence for both users and caregivers. Studies have demonstrated a high level of patient satisfaction, with 80% of users preferring NovoPen Echo to other pediatric insulin pens.

Potential Insulin Underdelivery from Prefilled and Reusable Insulin Pens in Cases of Premature Needle Withdrawal: A Laboratory Evaluation

BACKGROUND

Devices for the treatment of diabetes are not always used as recommended in good practice. Our aim was to evaluate potential insulin underdelivery in cases of premature needle withdrawal after injection with insulin pens, which is a commonly observed misuse, especially in young type 1 diabetes patients.

MATERIALS AND METHODS

Potential insulin underdelivery was evaluated using five prefilled insulin pens (lispro Kwikpen(®) [Eli Lilly, Indianapolis, IN], aspart Flexpen(®) [Novo Nordisk, Bagsvaerd, Denmark], glulisine Solostar(®) [Sanofi, Paris, France], detemir Flexpen(®) [Novo Nordisk], and glargine Solostar(®) [Sanofi]) and three reusable insulin pens (Humapen(®) Luxura HD with lispro cartridge [Eli Lilly], Novopen(®) Echo with aspart and detemir cartridge [Novo Nordisk], and JuniorSTAR(®) with glulisine and glargine cartridge [Sanofi]) in a laboratory. For each pen and insulin, we simulated premature needle withdrawal 2 and 3 s after an insulin injection of 5 and 10 units, respectively.

RESULTS

With prefilled pens, mean potential insulin underdelivery was 0.43±0.30 and 0.44±0.32 units after injection of 5 and 10 units, respectively. With reusable pens, mean potential insulin underdelivery was lower (0.29±0.13 and 0.29±0.12 units after injection of 5 and 10 units, respectively; P<0.001). The results were heterogeneous across pens, ranging from 2.6%/1.6% to 20.2%/8.6% of the selected insulin dose for prefilled/reusable pens, respectively (P<0.001).

CONCLUSIONS

Potential insulin underdelivery varies across prefilled and reusable insulin pens but may represent up to one-fifth of the total injected dose. Clinicians should be aware of the potential consequences of premature needle withdrawal and should reinforce insulin injection education.

Dose accuracy of a durable insulin pen with memory function, before and after simulated lifetime use and under stress conditions

OBJECTIVES

The objective of this study was to assess the dose accuracy of NovoPen® 5 in delivering low, medium and high doses of insulin before and after simulated lifetime use. A secondary objective was to evaluate the durability of the pen and its memory function under various stress conditions designed to simulate conditions that may be encountered in everyday use of an insulin pen.

RESEARCH DESIGN AND METHODS

All testing was conducted according to International Organization for Standardization guideline 11608-1, 2000 for pen injectors. Dose accuracy was measured for the delivery of 1 unit (U) (10 mg), 30 U (300 mg) and 60 U (600 mg) test medium in standard, cool and hot conditions and before and after simulated lifetime use. Dose accuracy was also tested after preconditioning in dry heat storage; cold storage; damp cyclical heat; shock, bump and vibration; free fall and after electrostatic charge and radiated field test. Memory function was tested under all temperature and physical conditions.

RESULTS

NovoPen 5 maintained dosing accuracy and memory function at minimum, medium and maximum doses in standard, cool and hot conditions, stress tests and simulated lifetime use. The pens remained intact and retained dosing accuracy and a working memory function at all doses after exposure to variations in temperature and after physical challenge.

CONCLUSIONS

NovoPen 5 was accurate at all doses tested and under various functionality tests. Its durable design ensured that the dose accuracy and memory function were retained under conditions of stress likely to be encountered in everyday use.

Dose accuracy of new versus used Novopen 4 insulin pens

OBJECTIVE

To our knowledge, no studies have been performed testing dose accuracy in both new and used patient insulin injection pens. We hypothesized that the dose accuracy of used (>1 year) insulin pens to be less accurate than that of new insulin pens and investigated whether possible differences influence the treatment. This study compared the dosing accuracy of 11 new and 11 used (>1 year) Novopen(®) 4 pens (Novo Nordisk, Bagsvaerd, Denmark).

MATERIALS AND METHODS

Dosing accuracy differences between new and used pens were studied by weighing the volume of the dosage of 8 international units of insulin (IU) and 32 IU of 11 pens. Each measurement was repeated 15 times. Whether the pens complied with the International Organization for Standardization (ISO) limits of 10% for 8 IU and 5% for 32 IU was tested. The statistical analyses were performed using the Mann-Whitney rank sum test (within Sigmaplot version 12.0; Systat Software, Chicago, IL), and a P value of <0.05 was considered to be statistically significant.

RESULTS

For the 8 IU dose, the mean delivered dose was 8.04 IU in new pens and 7.91 IU in used insulin pens. For the 32 IU dose, the mean delivered dose was 31.90 in new pens and 31.68 IU in used insulin pens. The difference in the median values between the two groups was statistically significant (P<0.001). Three individual doses in the 32 IU dose exceeded the ISO range in the lower range. The difference in mean variation coefficient between the two groups was also statistically significant (P<0.001).

CONCLUSIONS

There was a significant difference between the accuracy of new versus used insulin pens. More studies with larger sample sizes are necessary to confirm our findings and further elucidate the relationship between age of insulin pens and dose accuracy.

Safety and patient perception of an insulin pen with simple memory function for children and adolescents with type 1 diabetes--the REMIND study

OBJECTIVES

NovoPen Echo * is a durable pediatric insulin pen incorporating half-unit dosing starting at 0.5 units and a last-dose memory function. The REMIND † (Rating the Effects of Memory function in pediatric INsulin Devices) study primarily examined the safety of this new device by collecting data on technical complaints (TCs) related to adverse reactions (ARs) during use in a clinical setting.

METHODS

REMIND was an observational, multicenter study involving patients with type 1 diabetes on injection therapy, aged 2-18 years, from Canada, Finland, Israel and Sweden. Questionnaires and case report forms were completed at baseline and after using NovoPen Echo for 12-18 weeks.

RESULTS

In total, 358 patients participated and 315 completed. No serious ARs were reported. Three ARs related to TCs were reported, equated to one every 29 patient-years. Most patients found it 'easy' or 'somewhat easy' to read amount (99%) and hours lapsed (95%) since last dose using the memory function. The proportion of children self-injecting was significantly higher (71%) compared with those on previous device (66%, p=0.006). 80% of physicians answers reported they could train users in ≤10 minutes.

CONCLUSIONS

Only three device safety events were reported for NovoPen Echo. Physicians found it easy and quick to educate users. Patients/caregivers missed fewer injections and reported greater confidence in managing their insulin injections. As this was an observational study without controls or centralized laboratory testing, caution should be used in interpreting outcomes in glycemic control. Further studies are required to examine the effects of features such as memory function and half-unit dosing on HbA1c and hypoglycemia over a longer time period.