Practical aspects of insulin pen devices

New ways of insulin delivery

The predominant number of papers published from the middle of 2009 to the middle of 2010 about alternative routes of insulin administration (ARIA) were still about inhaled insulin. Long-term experience with Exubera was the topic of a number of publications that are also of relevance for inhaled insulin in general. The clinical trials performed with AIR insulin by Eli Lilly were published in a supplement issue of one diabetes technology journal and most of these will be presented. A number of other publications (also one in a high ranked journal) about their inhaled insulin were from another company: MannKind. The driving force behind Technosphere insulin (TI) - which is the only one still in clinical development - is Al Mann; he has put a lot of his personal fortune in this development. We will know the opinion of the regulatory authorities about TI in the near future; however, I am personally relatively confident that the Food and Drug Administration will provide TI with market approval. The more critical question for me is: will diabetologists and patients jump on this product once it becomes commercially available? Will it become a commercial success? In view of many negative feelings in the scientific community about inhaled insulin, it might be of help that MannKind publish their studies with TI systematically. Acknowledging being a believer in this route of insulin administration myself, one has to state that Exubera and AIR insulin had not offered profound advantages in terms of pharmacokinetic (PK) and pharmacodynamic (PD) properties in comparison with subcutaneously (SC) applied regular human insulin (RHI) and rapid-acting insulin analogues. The time-action profiles of these inhaled insulins were more or less comparable with that of rapid-acting insulin analogues. This is clearly different with TI which exhibits a strong metabolic effect shortly after application and a rapid decline in the metabolic effect thereafter; probably the duration of action is even too short (see postprandial glycaemic excursions with test meals in the publication by Rosenstock et al. in The Lancet (1)). In the end a number of aspects are of relevance for the success of a given product; one key aspect is clearly the price. However, for patients also practical aspects (handling, need for regular pulmonary function test etc.) are of importance. We shall have to see how creatively MannKind will handle all such questions. Until now Al Mann and his colleagues were able to manage a number of challenges during the clinical development process successfully, so one can have hopes for the market success of TI. However, it is clear that at the same time, if TI fails like Exubera did before, this will be the end for pulmonary insulin in general. Not too many original publications presenting data from clinical trials were published in the last year when it comes to oral insulin (OI), nasal insulin or transdermal insulin developments; simply none with transdermal insulin. Also at the last international congresses not many studies about ARIA were presented. At least in part this might be still a reflection of the shockwaves that the failure of Exubera has sent out to pharmaceutical companies and venture capitalists; they are quite reluctant to invest in any of these developments. However, a considerable number of reviews (in some cases more than original papers!) were published about ARIA. These reviews are listed for completeness, but in most cases are not further commented. OI is still the area of research most companies are active in; however, in some cases it is not clear how active they really are (e.g. Diabetology). Nevertheless, at least some companies are quite active and progressed in their clinical development programme close to market approval, e.g. the large Indian company Biocon is in late phase 3 with IN-105 and the small Israel-based company Oramed is in phase 2b. It appears that other interesting OI developments (e.g. Diasome) were not very active in the last year; at least they have not published new study results. It is clear that for companies that produce insulin themselves (e.g. Biocon) the costs of the good are not of such relevance as for companies that have to buy it commercially. For the latter ones a low bioavailability/biopotency compared with SC insulin administration can be a real hurdle when it comes to the price of their product. Despite some publications about nasal insulin, the overall activity with this route of insulin administration appears to be low; the same holds true for transdermal insulin. Insulin pens have gained more scientific interest in recent years, which is also reflected by an increase in publications, starting from practically nil 10 years ago to a solid number of five to 10 papers per year nowadays. Besides ARIA there are also attempts to increase the speed of insulin absorption after injection into the skin by applying it not into the SC tissue but intradermally or by heating up the skin above the SC insulin depot. Reading a number of papers that were not included in this chapter because they do not present any clinical data but are novel developments tested only in animal experiments so far, the clear message is that there is definitely not a lack of creativity/imagination amongst scientists; each year a plethora of new ideas for insulin application show up. Unfortunately not too many make it towards a full clinical development. As long as there is not a single successful product on the market that is based on a given ARIA approach, this area of research will not mature. For many patients, avoiding the need for SC injections is attractive; however, as long as no clear 'advantage' can be demonstrated, reimbursement will be difficult to achieve. Living in the time of evidence-based medicine it is clear that 'relevant' clinical advantages must be proven. The question is what is relevant. Is it just an improvement in metabolic control (= decrease in HbA1c)? Can this also mean that more patients are willing to start insulin therapy earlier than with conventional SC insulin therapy? With TI we have a product that has improved pharmacological properties (also in comparison to Exubera) for coverage of prandial insulin requirements. Subsequently, in the clinical trials performed, postprandial glycaemic excursions were lower than with SC injection of RHI or rapid-acting insulin analogues. This only in part (if at all) results in an improved metabolic control in general (= lower HbA1c) (see below). The outlook for 2011 is that there are chances that we shall have an inhaled insulin product on the market. Probably also the first OI will be submitted to the regulatory authorities for market approval or will even be available in less regulated markets. In order to select all relevant publications about new ways of insulin delivery I performed a PUBMED search and also checked the table of contents of a number of journals that publish heavily in this area of research as well references in the publications I found for additional references. Selection of the manuscripts from all publications was predominately based on the fact whether they presented data from clinical studies or not. The selected studies were critically reviewed for novelty and appropriate study design etc. In some cases also reviews about a given topic were selected if they provide relevant novel insights.

What can we learn from patient-reported outcomes of insulin pen devices?

Although a variety of effective treatment options are available for patients with type 1 or type 2 diabetes, many patients in the United States have difficulty reaching their glycemic goals. Patient adherence to insulin therapy, which often involves self-administered subcutaneous injections of insulin using either a vial and syringe or an insulin pen device, is often poor. Various factors associated with the type of injection device have been shown to influence the rate of patient adherence to insulin therapy. This article reviews patient-reported outcome (PRO) evidence from pediatric and adult studies that compared insulin pen devices with vial and syringe use. In a majority of these cases, patients preferred the pen devices over vial and syringe, stating advantages such as ease of use, convenience, greater confidence in their ability to properly administer the drug, and a greater perceived social acceptance. The pens were considered less painful than syringes and were associated with less needle fear. In addition, PRO evidence has directed pen technology design, leading to development of more advanced insulin pen devices. By appreciating the correlation between adherence to insulin regimens and a patient's device preference, clinicians can make improved treatment recommendations to facilitate achievement and maintenance of glycemic targets.

Usability and preference evaluation of a prefilled insulin pen with a novel injection mechanism by people with diabetes and healthcare professionals

OBJECTIVE

This cross-over usability study assessed the perceptions of, and preference for, FT (FlexTouch*), a new prefilled insulin pen, compared with KP (KwikPen†) another widely available prefilled insulin pen, among people with diabetes and healthcare professionals (physicians and nurses).

RESEARCH DESIGN AND METHODS

Participants were randomly assigned to start with either FT or KP. Following instruction on how to operate the pen, the participant performed several injections at different doses into a foam cushion and then answered written questions on ease of use, confidence and preference.

RESULTS

Seventy-nine people with diabetes and 81 healthcare professionals (40 physicians and 41 nurses) took part. Overall, most respondents preferred using FT (86%) to KP (7%; p < 0.001), found FT (85%) the easier pen to use versus KP (4%; p < 0.001), and would recommend FT (88%) rather than KP (6%; p < 0.001). Ratings for FT were also significantly higher than for KP on questions relating to the injection process, including ease of depressing the push-button and ease of injecting at three dose levels (20 International Units [IU], 40 IU and 60 IU [p < 0.001 for all]). Significantly more respondents chose FT as the pen that gave them most confidence in correct and complete insulin delivery (73% vs. 6% for KP; p < 0.001).

CONCLUSIONS

FT was rated significantly higher (all p < 0.001) for ease of use and confidence, and was preferred over KP by people with diabetes, physicians and nurses. The features of FT may improve the insulin injection experience for a wide range of users. A limitation of the usability questionnaire employed in this study is that it did not assess the factors that influence preference. Additional analyses could be conducted using multivariate regression to help elucidate the features of FT that appeal to different users.

Analysis: desirable attributes of insulin injection pens that drive patient preference and compliance

Insulin pens are used by approximately half of worldwide insulin users. Insulin pens have made insulin injections easier compared to traditional vial and syringe injections. In an article in this issue of Journal of Diabetes Science and Technology, Dr. Asakura discusses several important design parameters, which are considered during refillable insulin-injection pen design. Ease of cartridge replacement, insulin-dose setting dial use, injection, and prominence of audible clicks can all affect overall dose accuracy and user friendliness of insulin pens in patients suffering from diabetes and related comorbidities. These parameters, along with patient introduction from prescribing physicians and level of training provided, drives patient pen selection and injection-regimen compliance to control their blood sugar.

Analysis: linking laboratory data to human factors and inclusion of persons with disabilities in diabetes technology research

In this issue of Journal of Diabetes Science and Technology, Friedrichs and colleagues present a study of the injection force of four reusable insulin pens and another study of the dosing accuracy of three different insulin pens. For the study of injection force, the authors claim that lower injection force has numerous advantages for patients, including making use of pens easier for people with decreased hand strength. For the study of dosing accuracy, the authors state that dose accuracy is critical for glycemic control. Both study designs have significant strengths, including measurements of the variable of interest using two different methodologies and thorough documentation of methods and materials. However, the careful, precise measurements of injection force and dosing accuracy are not matched by equivalent precision supporting the significance of the studies. The authors do not provide any information about what measured injection force is easy or difficult for individuals with and without manual problems or what level of dosing inaccuracy is clinically significant. Therefore, the implications for practice remain unclear. Data about these and other relevant human factors are needed to provide meaningful context for laboratory measurements of diabetes technologies. Furthermore, researchers conducting studies of diabetes technology that include human subjects should intentionally recruit persons with disabilities so diabetes care professionals can know whether and how technical information about diabetes technology applies to the full range of patients, including those with disabilities.

Analysis of patient satisfaction with a prefilled insulin injection device in patients with type 1 and type 2 diabetes

In this issue of Journal of Diabetes Science and Technology, Hancu and colleagues present an observational 6-8-week Pan-European and Canadian prospective survey on patient satisfaction with a prefilled insulin injection device, the SoloSTAR pen device, in patients with type 1 and 2 diabetes (n = 6542). The SoloSTAR pen is one of several up-to-date insulin pens of high quality and characteristics that fit many of our patients with diabetes. The mainly excellent-good votes of the participants for the SoloSTAR are not surprising, as we have seen continuous improvements with prefilled pens, such as the SoloSTAR device. Several years ago, patients as well as health care providers found considerable differences between the available pen options. Nowadays, as almost all pen providers have clearly improved their products, the differences are much smaller; we are closer to a "perfect" prefilled pen device. Nevertheless, there is a need for more randomized controlled trials, ideally sponsored not by just one manufacturer, to be able to make clear statements toward different pen device aspects (e.g., accuracy of dosing, adherence to therapy, ease of use, and patient satisfaction). An additional handicap is the difficulty to get blinded study designs.

Evolution of devices in diabetes management

Recent technological advancements in insulin administration and glucose monitoring have allowed patients with diabetes to become increasingly involved in their own care. Devices replacing the traditional vial and syringe, such as insulin pens, are gaining popularity and offer simple and convenient insulin administration. Pen devices are associated with improved dose accuracy, reducing the risk of hypo- or hyperglycemia, and are continually being updated with new safety features in order to optimize their performance. In patients for whom glucose variability remains a problem, continuous subcutaneous insulin infusion via an implanted canula or continuous intraperitoneal insulin infusion via an implanted pump is safe and effective when used correctly, although cost can be a limitation. More accurate retrospective and real-time continuous monitoring devices, which can better detect blood glucose excursions, have become standard components of modern-day diabetes management. The most recent devices have sensor-signaling capabilities with wireless data transmission, leading to reduced time delay and more accurate alerts. Ultimately, though, while self-management remains a critical factor in improving glycemic control at present, human error may undermine even the most accurate treatment interventions. A key long-term goal in diabetes management is, therefore, to develop an automated and accurate closed-loop system for blood glucose monitoring and insulin delivery to better reflect the physiological mechanisms of glucose homeostasis and remove the "human" element. This "artificial pancreas" would offer the most innovative intervention for diabetes management and has the potential to considerably reduce the patient's burden of self-care.

Dose accuracy and injection force of disposable pens delivering pramlintide for the treatment of diabetes

BACKGROUND

The pen injection format, typically used for insulin administration, has been adapted for the injectable, noninsulin diabetes therapy pramlintide. Administered before major meals, pramlintide therapy requires two to four injections/day in addition to the patients' usual insulin injections. The dose accuracy and injection force was determined for the 60 and 120 µg pramlintide pens.

METHODS

Dose accuracy testing was conducted at two sites on multiple 60 µg (15, 30, and 60 µg doses) and 120 µg pens (60 and 120 µg doses) at prespecified temperatures (5-40 °C) and humidities (0-75%) using 29 G half-inch needles. All pens were stabilized under testing conditions for 4 h prior to testing. One site used a compression load cell (Zwick device) to test pens; one site performed tests manually. Injection-force testing was conducted at one site on multiple 60 and 120 µg pens at multiple temperatures (18-28 °C) and humidities (25-75%) using 29 and 31 G half-inch needles and an injection speed of 150 m/min. Injection-force testing was performed using a Zwick device.

RESULTS

Dose accuracy for all pens tested, regardless of location, reproducibly met/exceeded acceptance criteria. Mean percentage of dose accuracy was 96.04 to 102.45% [standard deviations (SDs) 0.3 to 1.4 µg] for the 60 µg pen and 98.16 to 101.83% (SDs 0.4 to 2.5 µg) for the 120 µg pen. The average injection force across both pens did not exceed 7 N regardless of needle size.

CONCLUSIONS

High dose accuracy and low injection force were observed for the 60 and 120 µg pens under a variety of conditions.

Analysis of symposium articles on insulin pen devices and alternative insulin delivery methods

Insulin therapy is a fundamental component of diabetes management, yet there is often resistance to insulin initiation by both prescribers and patients. A barrier to insulin use is the perceived shortcomings with the traditional vial-and-syringe administration method (inconvenience, difficulty of use, association with disease and addiction, etc.). This symposium in the journal discusses the advantages of alternative insulin delivery methods, primarily insulin pen devices. Although these administration methods, especially insulin pens, have some clear advantages over the vial/syringe, there are also limitations to their use and careful patient selection and education are still needed.