Injection Technique and Pen Needle Design Affect Leakage From Skin After Subcutaneous Injections

Backflow reduction in local injection therapy with gelatin formulations

The local injection of therapeutic drugs, including cells, oncolytic viruses and nucleic acids, into different organs is an administrative route used to achieve high drug exposure at the site of action. However, after local injection, material backflow and side effect reactions can occur. Hence, this study was carried out to investigate the effect of gelatin on backflow reduction in local injection. Gelatin particles (GPs) and hydrolyzed gelatin (HG) were injected into tissue models, including versatile training tissue (VTT), versatile training tissue tumor-in type (VTT-T), and broiler chicken muscles (BCM), using needle gauges between 23 G and 33 G. The backflow material fluid was collected with filter paper, and the backflow fluid rate was determined. The backflow rate was significantly reduced with 35 μm GPs (p value < .0001) at different concentrations up to 5% and with 75 μm GPs (p value < .01) up to 2% in the tissue models. The reduction in backflow with HG of different molecular weights showed that lower-molecular-weight HG required a higher-concentration dose (5% to 30%) and that higher-molecular-weight HG required a lower-concentration dose (7% to 8%). The backflow rate was significantly reduced with the gelatin-based formulation, in regard to the injection volumes, which varied from 10 μL to 100 μL with VTT or VTT-T and from 10 μL to 200 μL with BCM. The 35 μm GPs were injectable with needles of small gauges, which included 33 G, and the 75 μm GPs and HG were injectable with 27 G needles. The backflow rate was dependent on an optimal viscosity of the gelatin solutions. An optimal concentration of GPs or HG can prevent material backflow in local injection, and further studies with active drugs are necessary to investigate the applicability in tumor and organ injections.

Modeling drug transport and absorption in subcutaneous injection of monoclonal antibodies: Impact of tissue deformation, devices, and physiology

The pharmaceutical industry has experienced a remarkable increase in the use of subcutaneous injection of monoclonal antibodies (mAbs), attributed mainly to its advantages in reducing healthcare-related costs and enhancing patient compliance. Despite this growth, there is a limited understanding of how tissue mechanics, physiological parameters, and different injection devices and techniques influence the transport and absorption of the drug. In this work, we propose a high-fidelity computational model to study drug transport and absorption during and after subcutaneous injection of mAbs. Our numerical model includes large-deformation mechanics, fluid flow, drug transport, and blood and lymphatic uptake. Through this computational framework, we analyze the tissue material responses, plume dynamics, and drug absorption. We analyze different devices, injection techniques, and physiological parameters such as BMI, flow rate, and injection depth. Finally, we compare our numerical results against the experimental data from the literature.

Poroelastic Characterization and Modeling of Subcutaneous Tissue Under Confined Compression

Subcutaneous tissue mechanics are important for drug delivery. Yet, even though this material is poroelastic, its mechanical characterization has focused on its hyperelastic response. Moreover, advancement in subcutaneous drug delivery requires effective tissue mimics such as hydrogels for which similar gaps of poroelastic data exist. Porcine subcutaneous samples and gelatin hydrogels were tested under confined compression at physiological conditions and strain rates of 0.01%/s in 5% strain steps with 2600 s of stress relaxation between loading steps. Force-time data were used in an inverse finite element approach to obtain material parameters. Tissues and gels were modeled as porous neo-Hookean materials with properties specified via shear modulus, effective solid volume fraction, initial hydraulic permeability, permeability exponent, and normalized viscous relaxation moduli. The constitutive model was implemented into an isogeometric analysis (IGA) framework to study subcutaneous injection. Subcutaneous tissue exhibited an initial spike in stress due to compression of the solid and fluid pressure buildup, with rapid relaxation explained by fluid drainage, and longer time-scale relaxation explained by viscous dissipation. The inferred parameters aligned with the ranges reported in the literature. Hydraulic permeability, the most important parameter for drug delivery, was in the rangek 0 ∈ [ 0.142 , 0.203 ] mm4 /(N s). With these parameters, IGA simulations showed peak stresses due to a 1-mL injection to reach 48.8 kPa at the site of injection, decaying after drug volume disperses into the tissue. The poro-hyper-viscoelastic neo-Hookean model captures the confined compression response of subcutaneous tissue and gelatin hydrogels. IGA implementation enables predictive simulations of drug delivery.

Clinical Investigation of Large Volume Subcutaneous Delivery up to 25 mL for Lean and Non-Lean Subjects

PURPOSE

To evaluate the clinical feasibility and tolerability of large volume subcutaneous delivery at different injection depths for lean and non-lean subjects.

METHODS

A single-center, randomized, subject-blinded, crossover study in 62 healthy subjects was conducted to evaluate delivery of a 10-cP solution containing hyaluronic acid. Subjects were separated into lean and non-lean cohort by SC thickness. A syringe pump was used to study the effect of different volumes (5, 12, 25 mL) of a viscous placebo solution and needle lengths (6, 9 and 12 mm) delivered at 0.5 mL/min.

RESULTS

Across all treatments, injection sites were observed to have negligible leakage, ~34 kPa of back pressure, and VAS of mild pain with higher pain from needle insertion than during injection. While mild to moderate erythema was the most frequently reported ISR and edema was most prominent for 25 mL injections, all ISRs were resolved within 4 hours post injection. Subjects were unbothered by ISRs across all treatments and rated them as low distress scores (average 1.0-1.5 out of 6).

CONCLUSION

SC injection of 25 mL is feasible and tolerable using a low-pain formulation for abdomen injection irrespective of subcutaneous thickness and injection depths at a delivery rate of 0.5 mL/min.

Computational modeling of the effect of skin pinch and stretch on subcutaneous injection of monoclonal antibodies using autoinjector devices

Subcutaneous injection of monoclonal antibodies (mAbs) has experienced unprecedented growth in the pharmaceutical industry due to its benefits in patient compliance and cost-effectiveness. However, the impact of different injection techniques and autoinjector devices on the drug's transport and uptake is poorly understood. Here, we develop a biphasic large-deformation chemomechanical model that accounts for the components of the extracellular matrix that govern solid deformation and fluid flow within the subcutaneous tissue: interstitial fluid, collagen fibers and negatively charged proteoglycan aggregates. We use this model to build a high-fidelity representation of a virtual patient performing a subcutaneous injection of mAbs. We analyze the impact of the pinch and stretch methods on the injection dynamics and the use of different handheld autoinjector devices. The results suggest that autoinjector base plates with a larger device-skin contact area cause significantly lower tissue mechanical stress, fluid pressure and fluid velocity during the injection process. Our simulations indicate that the stretch technique presents a higher risk of intramuscular injection for autoinjectors with a relatively long needle insertion depth.

Mechanical characterisation of commercial artificial skin models

Understanding of the mechanical properties of skin is crucial in evaluating the performance of skin-interfacing medical devices. Artificial skin models (ASMs) have rapidly gained attention as they are able to overcome the challenges in ethically sourcing consistent and representative ex vivo animal or human tissue models. Although some ASMs have become commercialised, a thorough understanding of the mechanical properties of the skin models is crucial to ensure that they are suitable for the purpose of the study. In the present study, skin and fat layers of ASMs (Simulab®, LifeLike®, SynDaver® and Parafilm®) were mechanically characterised through hardness, needle insertion, tensile and compression testing. Different boundary constraint conditions (minimally and highly constrained) were investigated for needle insertion testing, while anisotropic properties of the skin models were investigated through different specimen orientations during tensile testing. Analysis of variance (ANOVA) tests were performed to compare the mechanical properties between the skin models. Properties of the skin models were compared against literature to determine the suitability of the skin models based on the material property of interest. All skin models offer relatively consistent mechanical performance, providing a solid basis for benchtop evaluation of skin-interfacing medical device performance. Through prioritising models with mechanical properties that are consistent with human skin data, and with limited variance, researchers can use the data presented here as a toolbox to select the most appropriate ASM for their particular application.

SubQ-Sim: A Subcutaneous Physiologically Based Biopharmaceutics Model. Part 1: The Injection and System Parameters

PURPOSE

To construct a detailed mechanistic and physiologically based biopharmaceutics model capable of predicting 1) device-formulation-tissue interaction during the injection process and 2) binding, degradation, local distribution, diffusion, and drug absorption, following subcutaneous injection. This paper is part of a series and focusses on the first aspect.

METHODS

A mathematical model, SubQ-Sim, was developed incorporating the details of the various substructures within the subcutaneous environment together with the calculation of dynamic drug disposition towards the lymph ducts and venous capillaries. Literature was searched to derive key model parameters in healthy and diseased subjects. External factors such as body temperature, exercise, body position, food or stress provide a means to calculate the impact of "life events" on the pharmacokinetics of subcutaneously administered drugs.

RESULTS

The model predicts the tissue backpressure time profile during the injection as a function of injection rate, volume injected, solution viscosity, and interstitial fluid viscosity. The shape of the depot and the concentrations of the formulation and proteins in the depot are described. The model enables prediction of formulation backflow following premature needle removal and the resulting formulation losses. Finally, the effect of disease (type 2 diabetes) or the presence of recombinant human hyaluronidase in the formulation on the injection pressure, are explored.

CONCLUSIONS

This novel model can successfully predict tissue back pressure, depot dimensions, drug and protein concentration and formulation losses due to incorrect injection, which are all important starting conditions for predicting drug absorption from a subcutaneous dose. The next article will describe the absorption model and validation against clinical data.

Design Development of the SMARTCLIC®/CLICWISE® Injection Device for Self-Administered Subcutaneous Therapies: Findings from Usability and Human Factor Studies

INTRODUCTION

An easy-to-use, multiuse, single-patient, electromechanical autoinjector, the SMARTCLIC®/CLICWISE® injection device, was recently developed to improve the self-administration options available to patients with chronic inflammatory disease treated with biologic agents. An extensive series of studies were conducted to guide the design and development of this device and to ensure its safety and effectiveness.

METHODS

Participants in two user preference studies and three formative human factor (HF) studies evaluated evolving iterations of the autoinjector device, dose dispenser cartridge, graphical user interface, and informational materials; participants in a summative HF test subsequently assessed the final proposed commercially representative product. In the user preference studies, rheumatologists and patients with chronic inflammatory disease, interviewed online and in-person, provided feedback on the design and functionality of four prototypes. In the HF studies, the safety, effectiveness, and usability of adapted prototypes were assessed under simulated-use conditions by patients with chronic inflammatory disease, caregivers, and healthcare professionals (HCPs). The safety and effectiveness of the final refined device and system were confirmed in a summative HF test by patients and HCPs in simulated-use scenarios.

RESULTS

Rheumatologists (n = 204) and patients (n = 39) interviewed in the two user preference studies provided feedback on the device size, feature ergonomics, and usability that guided prototype development in the subsequent formative HF studies. Observations from patients, caregivers, and HCPs (n = 55) participating in the latter studies yielded additional critical design revisions that culminated in development of the final device and system. Of 106 injection simulations conducted in the summative HF test, all resulted in successful medication delivery, and no potential harms were associated with injection-related use events.

CONCLUSION

Findings from this research facilitated development of the SmartClic/ClicWise autoinjector device and demonstrated that it could be used safely and effectively by participants representative of the intended-use population of patients, lay caregivers, and HCPs.

An analysis of the effect of syringe barrel volume on performance and user perception

In the market, there are many types and shapes of syringes. One of the groupings of syringe types is based on barrel volume. The shape of the product design affects performance and user perception. The aim of this study is to investigate the effect of barrel volume on its performance and user perception. We performed analysis following international organization for standardization 7886 procedures on syringe with 1 mL, 3 mL, 5 mL, and 10 mL volume. In addition, a user perception test was conducted on 29 respondents using a questionnaire with the Likert chart method. This study indicates that the bigger the syringe volume, the larger the dead space and the force to operate the piston are. A larger syringe volume also raises the volume that changes due to the plunger position increase. Meanwhile, the barrel volume does not affect water and water leakage, as we did not observe any leak during the syringe tests in our experiment. In addition, the user perception test shows that the barrel's length influences the ease of device control during the injection. The volume of the barrel negatively correlated with its effect to the environment. The safety features of all syringes are similar except for the 3 mL syringe, which has a value of 0.1 points difference to other syringes.

Optimizing autoinjector devices using physics-based simulations and Gaussian processes

Autoinjectors are becoming a primary drug delivery option to the subcutaneous space. These devices need to work robustly and autonomously to maximize drug bio-availability. However, current designs ignore the coupling between autoinjector dynamics and tissue biomechanics. Here we present a Bayesian framework for optimization of autoinjector devices that can account for the coupled autoinjector-tissue biomechanics and uncertainty in tissue mechanical behavior. The framework relies on replacing the high fidelity model of tissue insertion with a Gaussian process (GP). The GP model is accurate yet computationally affordable, enabling a thorough sensitivity analysis that identified tissue properties, which are not part of the autoinjector design space, as important variables for the injection process. Higher fracture toughness decreases the crack depth, while tissue shear modulus has the opposite effect. The sensitivity analysis also shows that drug viscosity and spring force, which are part of the design space, affect the location and timing of drug delivery. Low viscosity could lead to premature delivery, but can be prevented with smaller spring forces, while higher viscosity could prevent premature delivery while demanding larger spring forces and increasing the time of injection. Increasing the spring force guarantees penetration to the desired depth, but it can result in undesirably high accelerations. The Bayesian optimization framework tackles the challenge of designing devices with performance metrics coupled to uncertain tissue properties. This work is important for the design of other medical devices for which optimization in the presence of material behavior uncertainty is needed.

Factors Affecting Performance of Insulin Pen Injector Technology: A Narrative Review

BACKGROUND

Insulin treatment is an essential hormone replacement therapy for the survival of people with type 1 diabetes and is often used for treatment in type 2 diabetes, particularly as the disease progresses. Advances in insulin therapy have been made since its discovery, including production of human insulin and development of insulin analogs with improved efficacy and safety profiles. The different types of available insulin formulations allow health care professionals to personalize treatment to an individual's needs. Generally, insulin requires parenteral administration via subcutaneous injection owing to very low oral bioavailability.

METHODS

This article reviews the human, technological, economical, and regulatory factors affecting the performance of insulin pens and the relationship between them. Opportunities and challenges that insulin pen injections may encounter in the future are also considered.

RESULTS

Insulin delivery devices, together with other factors, influence dose accuracy, convenience, and quality of life, contributing to easier medication administration with high efficacy and safety. For patients, ease of use, fast and accurate drug delivery, and painless injection are the most valuable features of an insulin injection device. For manufacturers, technological feasibility and economic viability also need to be considered when developing injection devices.

CONCLUSION

Insulin pen injectors are generally preferred over vial and syringe, although access may be limited in some health care systems. Insulin pen injectors can adapt to different insulin regimens and formulations and have the potential to acquire dosing data in real time.

Modeling large-volume subcutaneous injection of monoclonal antibodies with anisotropic porohyperelastic models and data-driven tissue layer geometries

Subcutaneous injection of therapeutic monoclonal antibodies (mAbs) has become one of the fastest-growing fields in the pharmaceutical industry. The transport and mechanical processes behind large volume injections are poorly understood. Here, we leverage a large-deformation poroelastic model to study high-dose, high-speed subcutaneous injection. We account for the anisotropy of subcutaneous tissue using of a fibril-reinforced porohyperelastic model. We also incorporate the multi-layer structure of the skin tissue, generating data-driven geometrical models of the tissue layers using histological data. We analyze the impact of handheld autoinjectors on the injection dynamics for different patient forces. Our simulations show the importance of considering the large deformation approach to model large injection volumes. This work opens opportunities to better understand the mechanics and transport processes that occur in large-volume subcutaneous injections of mAbs.

The hypodermic syringe performance based on the ISO 7886-1:2017: A narrative review

A syringe is used to inject fluid or medicine into the patient's soft tissue. The main components of the syringe were the needle, barrel, and plunger. The use of syringes in the medical world is relatively high, and especially since the COVID-19 pandemic, the use of hypodermic syringes increased sharply due to vaccination. The syringe used must be effective and of good quality, so the International Organization for Standardization (ISO) has published test procedures and minimum specifications for hypodermic syringes. The performance of the syringe can be observed from the dead space, force piston operation, water and air leakage, and fitting position of the plunger in the barrel. This review shows that most researchers use the weighing method to measure the dead space, although some use other methods. The researchers found that most of the products met the minimum specifications of the ISO, and that the dimensions and shape of the syringe affected the dead space. Researchers have not examined other performance measures recommended by the ISO. Researchers have focused more on force injection than force piston operation, leakage after injection or back spray than air and water leakage, and reduction the friction of the plunger without considering the fitting position of the plunger in the barrel.

Needle-free injection of basal insulin improves fasting glucose variability as assessed by continuous glucose monitoring in T2DM: a prospective randomized multicenter open-label crossover study

BACKGROUND

Fasting glucose variability (FGV) extensively promotes the onset and development of diabetic complications. This study aimed to evaluate the FGV in type 2 diabetes mellitus (T2DM) patients administered basal insulin using a needle-free insulin injector (NFII).

RESEARCH DESIGN AND METHODS

This was a prospective randomized multicenter open-label crossover study. We randomly assigned 48 T2DM patients to receive basal insulin by NFII or conventional insulin pen (CIP) for 7-14 days and were then crossed over after washout. We conducted continuous glucose monitoring to investigate the FGV, our primary outcome was a composite parameter of the FGV with a fasting blood glucose target between 4.4 and 6.1 mmol/L.

RESULTS

The coefficient of variation for sensor glucose at 6 a.m. with CIP was 11.67 (8.70,14.81)% vs. 9.48 (6.48,12.24)% with NFII (p = 0.003), and the coefficient of variation for mean sensor glucose at 5-6 a.m. with CIP was 12.70 (9.17,16.56)% vs. 9.23 (7.01,11.98)% with NFII (p < 0.001). The overall basal insulin dosage with CIP injection was 18.00 (16.00, 20.00) IU vs. 16.00 (12.00, 19.00) IU during NFII (p < 0.003).

CONCLUSION

Compared with CIP, the use of the NFII to inject basal insulin improved FGV in T2DM.

CLINICAL TRIAL REGISTRATION

https://www.chictr.org.cn Identifier is ChiCTR2000034674.

Investigation of Association Between Insulin Injection Technique and Blood Glucose Control in Patients with Type 2 Diabetes

BACKGROUND

The appropriate insulin injection skill is essential for optimal blood sugar control in patients with diabetes. However, the art of insulin injection is still not well understood in numerous medical centers.

OBJECTIVES

This study was designed to determine the association between appropriate insulin injection and blood glucose control in patients with type 2 diabetes in Yazd, Iran.

METHODS

This cross-sectional study was conducted on 301 patients with type 2 diabetes who referred to Diabetes Research Center in Yazd within August 2020 to February 2021. Based on simple random sampling, the subjects with inclusion criteria, such as age >18 years, using an insulin pen for at least 3 months, and self-injection, were selected. The insulin injection technique was evaluated by a 13-item researcher-made questionnaire. The total score of this questionnaire was 26, and its validity and reliability were confirmed. The data were analyzed using SPSS software (version 20).

RESULTS

The mean age of the participants was 59.83 ± 10.26 years, and 60.1% had primary school or less education. Most participants (87%) used a needle more than five times, and almost half of them (53.5%) did not rotate the injection sites properly. The patients who reported pain during injection had statically lower injection scores than others (17.90 vs. 19.38, P = 0.001). There was a significant negative correlation between insulin injection score with fasting blood sugar (β = -0.232, P < 0.001), two-hour postprandial glucose (β = -0.164, P = 0.005), and hemoglobin A1c (HbA1c) level (β = -0.263, P < 0.001).

CONCLUSIONS

None of the patients in this study fully followed the principles of a proper injection, which can lead to pain during injection, lipohypertrophy, hyperglycemia, and increased HbA1c levels.

Efficacy of mesenchymal stem cell-delivery using perpendicular multi-needle injections to the skin: Evaluation of post-ejection cellular health and dermal delivery

AIM

Mesenchymal stem cell (MSC)-therapy is increasingly being evaluated in clinical trials. Dermal delivery is not only time consuming but also unreliable, potentially hampering the therapeutic result. Therefore, qualification of cell delivery protocols is essential. This study evaluated a clinically relevant automated multi-needle injection method for cutaneous MSC-therapy, allowing the skin to be readily and timely treated, by assessing both the cellular health post-ejection and dermal delivery.

METHODS

Following dispensation through the injector (31 G needles: 9- or 5-pin) the cellular health and potency (perceived- and long-term (12 h) viability, recovery, metabolism, adherence, proliferation and IDO1-expression) of adipose-derived stem cells (10-20-50 ×10⁶ cells/ml) were assessed in vitro in addition to dermal delivery of solution in human skin.

RESULTS

No significant detrimental effect on the perceived cell viability, recovery, metabolism, adherence or IDO1-expression of either cell concentration was observed. However, the overall long-term viability and proliferation decreased significantly regardless of cell concentration, nonetheless marginally. An injection depth above 1.0 mm resulted in all needles piercing the skin with dermal delivery from up to 89% needles and minimal reflux to the skin surface, and the results were confirmed by ultrasound and histology.

CONCLUSION

The automated injector is capable of delivering dermal cell-doses with an acceptable cell quality.

Reducing bruising and pain through enhancement of subcutaneous anticoagulant injection techniques: a best practice implementation project

INTRODUCTION

Subcutaneous delivery of anticoagulant therapy is a common treatment modality across multiple medical disciplines. However, postinjection complications of bruising and pain continues to be a problem that has the propensity to affect patients physically and psychologically. A review of literature revealed a set of recommended injection techniques that have shown to improve these clinical outcomes.

OBJECTIVES

The project aims to utilize an evidence implementation framework to introduce evidence-based injection technique, for the reduction of postinjection complications.

METHODS

A best practice implementation project was administered across three adult- cardiology and cardio-thoracic general wards in Singapore from March 2018 to February 2019. The Joanna Briggs Institute (JBI)'s framework of evidence implementation was utilized to enable change. A baseline audit was carried out to ascertain existing injection practices. Guided by the latest evidence, a new subcutaneous injection workflow was created and disseminated. Follow-up audits were held at 1 and 8-month postimplementation to assess compliance to the new subcutaneous injection workflow and the sustainment of change. Data were consolidated and analysed with the aid of JBI Practical Application of Clinical Evidence System. Barriers to change were also identified and addressed with the aid of JBI's Getting Research into Practice tool.

RESULTS

A large variation of subcutaneous injection techniques was observed at the baseline audit. At 1-month postimplementation, overall compliance with the new subcutaneous injection workflow was assessed to be 73.3%. Criteria 2 and 3 of the JBI Practical Application of Clinical Evidence System audit criteria improved from the baseline values (9.1-80%; 0-93.3%). At 8-month postimplementation, compliance rate remained high (83%) following strategies to reinforce and sustain change. Participants complied to Criteria 1 at all stages of the project. Correspondingly, the incidence of bruising reduced from baseline, with a relative risk reduction of 52% (1 month) and 29% (8 months). Median pain also decreased from the baseline, with an improvement from 2.0 (1.0-3.0) to 0.0 (0.0-1.0).

CONCLUSION

Introduction and sustainment of change requires careful planning and execution. JBI's framework of evidence implementation is an effective model to guide this process. This project also highlighted the value of continuous learning, clinical update and practice standardization. This is especially important in the current climate of nursing mobility worldwide and the associated practice variations based on nursing education and experience.

Insulin Injection Practices in a Population of Canadians with Diabetes: An Observational Study

INTRODUCTION

Proper insulin injection technique has demonstrated positive clinical outcomes in patients with diabetes. A Canadian-based practice reflective was undertaken to evaluate the current state of understanding of injection technique practices by patients administering insulin, and the importance physicians place on proper injection technique.

METHODS

Twenty-four sites across Canada completed a practice profile survey and enrolled adult non-pregnant patients with either type 1 or type 2 diabetes injecting insulin using an insulin pen. Seven areas of proper injection technique to be evaluated were identified by the study steering committee: size of injection site, use of a skin lift, needle reuse, length of the needle, duration of the needle in the skin, injection into lipohypertrophic tissue, and applied injection force. During a scheduled visit, each patient filled out the Injection Technique Survey and the physician documented the answers via an electronic database.

RESULTS

Almost all physicians surveyed agreed (96%) that proper insulin injection technique is important or very important and 80% indicated they were either completely confident or fairly confident in discussing overall insulin injection technique. All patients surveyed were making at least one insulin injection technique error within the following categories: applied injection force (76%), area size of injection site (64%), duration of pen needle in skin (61%), pen needle reuse (39%), performs a skin lift with a 4 or 5 mm needle (38%), uses a longer pen needle than required (34%), and injection of insulin into lipohypertrophic tissue (37%).

CONCLUSION

Patients commonly make insulin injection errors. Patient and physician education on optimal insulin injection technique continues to be an unmet medical need for the treatment of patients with diabetes. Prospective trials examining the impact of new technology, diabetes educational teams, and e-learning as educational interventions are potential avenues to explore in future studies to support improved insulin injection technique.

The Injection Technique Factor: What You Don't Know or Teach Can Make a Difference

IN BRIEF To be consistently effective, insulin must be delivered into subcutaneous tissue. If insulin is delivered intramuscularly, its uptake and action become variably faster, leading to suboptimal, inconsistent glucose control. The best strategy to avoid intramuscular injection is to use the shortest needles available. Injection sites should be rotated systematically to prevent lipohypertrophy, which also substantially affects insulin uptake and action. New evidence-based insulin delivery recommendations are available, and awareness of them should lead to more effective use of insulin therapy, improved clinical outcomes, and considerable cost savings.

Subcutaneous Administration of Biotherapeutics: An Overview of Current Challenges and Opportunities

Subcutaneous delivery of biotherapeutics has become a valuable alternative to intravenous administration across many disease areas. Although the pharmacokinetic profiles of subcutaneous and intravenous formulations differ, subcutaneous administration has proven effective, safe, well-tolerated, generally preferred by patients and healthcare providers and to result in reduced drug delivery-related healthcare costs and resource use. The aim of this article is to discuss the differences between subcutaneous and intravenous dosing from both health-economic and scientific perspectives. The article covers different indications, treatment settings, administration volumes, and injection devices. We focus on biotherapeutics in rheumatoid arthritis (RA), immunoglobulin-replacement therapy in primary immunodeficiency (PI), beta interferons in multiple sclerosis (MS), and monoclonal antibodies (mAbs) in oncology. While most subcutaneous biotherapeutics in RA, PI, and MS are self-administered at home, mAbs for oncology are still only approved for administration in a healthcare setting. Beside concerns around the safety of biotherapeutics in oncology, a key challenge for self-administration in this area is that doses and dosing volumes can be comparatively large; however, this difficulty has recently been overcome to some extent by the development of high-concentration solutions, the use of infusion pumps, and the coadministration of the dispersion enhancer hyaluronidase. Furthermore, given the increasing number of biotherapeutics being considered for combination therapy and the high dosing complexity associated with these, especially when administered intravenously, subcutaneous delivery of fixed-dose combinations might be an alternative that will diminish these burdens on healthcare systems.

Efficacy, safety and acceptability of the new pen needle 34G × 3.5 mm: a crossover randomized non-inferiority trial; AGO 02 study

OBJECTIVE

Insulin injection aspects, such as fear of injection and pain, directly affect glycemic control, patient adherence and quality of life. Use of thinner and shorter needles could increase acceptance of injections. The aim of the study is to evaluate the non-inferiority of the new 34G × 3.5 mm needle compared to a 32G × 4 mm in patients with diabetes treated with insulin.

METHODS

This is an open, randomized, two-period crossover, non-inferiority trial. Every treatment period lasted 3 weeks. Patients with type 1 or type 2 diabetes, treated with multiple daily insulin injections, were randomly assigned to receive a 34G × 3.5 mm or a 32G × 4 mm pen needle. The primary endpoint was the non-inferiority of the 34G × 3.5 mm in comparison with the 32G × 4 mm pen needle in terms of percentage absolute change of blood fructosamine (% |ΔFru|), using a non-inferiority margin of 20%.

RESULTS

Overall 77 patients were randomized and 73 completed the study. Patients characteristics were: 52% male, 80.5% affected by type 1 diabetes, mean age 52 years (±14.6), mean BMI 24.5 kg/m² (±5.6), HbA1c 8% (±1.1) and baseline fructosamine level 350 µmol/l (±84). Mean fructosamine levels increased by 0.56 µmol/l with the 34G needle, while a reduction of 7.29 μmol/l was documented with the 32G needle. The difference between the two groups (7.84 μmol/l) was not statistically significant (p = .27). The % |ΔFru| between the two groups was 7.55% (95% CI 5.67-9.44), meeting the non-inferiority criterion. Glycemic variability, expressed as standard deviation of fasting blood glucose and post-prandial glucose, was not different between the two treatment groups (p = .63 and p = .77, respectively).

CONCLUSIONS

The 34G × 3.5 mm needle was non-inferior to the 32G × 4 mm needle regarding fructosamine levels and glycemic variability supporting the suitability of the 34G × 3.5 mm needle for insulin injection in patients with diabetes.

CLINICAL TRIAL REGISTRATION

NCT02690467.

Impact of Injection Speed, Volume, and Site on Pain Sensation

BACKGROUND

Painful subcutaneous insulin injections may decrease treatment compliance. Improving injection comfort therefore represents a particular area of technological research in which steady progress has been made since the introduction of the insulin pen in 1985. Injection pain can be influenced by many variables, but relatively little is known about their impact. This study investigated the impact of injection volume (range 0-2250 µL), speed (range 0-800 µL/sec), and site (abdomen vs thigh) on pain sensation.

METHOD

In random order, patients (n = 80) with type 1 or type 2 diabetes received 24 saline injections subcutaneously through a 27G ultra-thin-wall needle. Injections were performed in the abdomen (n = 19) and thigh (n = 5) with predefined speed-volume combinations. For each injected speed-volume combination, patients scored their pain sensation on a 100 mm visual analog scale (VAS).

RESULTS

The mean pain scores for speed-volume combinations were all in the lower part (<20 mm) of the VAS, indicating zero to mild pain. Pain sensation was statistically higher ( P < .05) with the 2250 µL volume compared to other injection volumes (range 4.3-5.1 mm) and with thigh compared to abdomen injections (2.1 mm). Pain sensation did not change with increasing injection speed. Patient acceptance of the injection pain was high for all injections (range 93.7-98.7%).

CONCLUSIONS

In summary, large volume and thigh injections are rated more painful, but the clinical impact of these findings is likely marginal considering the low absolute pain levels and high patient acceptance rates. Injection speed does not influence pain sensation.

Safety of the reuse of needles for subcutaneous insulin injection: A systematic review and meta-analysis

OBJECTIVE

Many people with diabetes often reuse disposable needles for subcutaneous insulin injection. We aimed to identify, critically appraise and summarize the available evidence about the safety of this practice.

DESIGN

Systematic review in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement.

DATA SOURCES

MEDLINE (via PubMed), CINALH (via EBSCO), SCOPUS, Web of Science, Cochrane Central Register of Controlled Trials and Open Grey were searched from their inception to December 2015, with no language restrictions.

REVIEW METHODS

Epidemiologic and experimental studies assessing adverse effects of reusing needles in people of any age or sex, with or without diabetes, were included. Two reviewers independently assessed the methodological quality of included studies using a multi-design tool.

RESULTS

In total, 25 studies were included. All studies had a high risk of bias and data from only nine studies could be pooled. Five studies showed no association between infection at site of injection and reuse of needles (risk difference=-0.00; 95% confidence interval=-0.12-0.11; P=0.99); heterogeneity between these studies was substantial (I(2)=66%; P=0.02). Five cross-sectional studies showed an association between lipohypertrophy and needle reuse (risk difference=0.16, 95% confidence interval=0.05-0.28, P=0.006); there was strong evidence of heterogeneity between these studies (I(2)=87%; P<0.001). Pooled data of two studies with no evidence of heterogeneity between them showed more perceived pain among reusers (risk difference=0.24; 95% confidence interval=0.06-0.43; P=0.006). Reusing a pen needle or disposable syringe-needle was not associated with worse glycaemic control.

CONCLUSIONS

There is currently no clear scientific evidence to suggest for or against the reuse of needles for subcutaneous insulin injection. This practice is very common among people with diabetes; consequently, further research is necessary to establish its safety.