Skin and subcutaneous adipose layer thickness in adults with diabetes at sites used for insulin injections: implications for needle length recommendations

Pharmacokinetic differences between subcutaneous injection and intradermal microneedle delivery of protein therapeutics

Protein therapeutics are essential in the treatment of various diseases, but most of them require parenteral administration. Since intravenous and subcutaneous injections are associated with discomfort and pain, other routes have been investigated including intradermal microneedle delivery. Microneedles are shorter than hypodermic needles and therefore minimize contact with pain receptors in deeper skin layers. But the differences in anatomical and physiological characteristics of dermis and subcutis can potentially result in varying protein penetration through the skin, absorption, and metabolism. This review summarizes pharmacokinetic studies that compare the administration of protein therapeutics by subcutaneous injections and different types of microneedles intradermally including hollow, dissolvable, coated, and hydrogel-forming microneedles. Across animal and human studies, hollow microneedle delivery resulted in quicker and higher peak plasma levels of proteins and comparable bioavailability to subcutaneous injections potentially due to the extensive network of lymphatic and blood vessels in the dermis. In case of dissolvable and coated microneedles, drug release kinetics depend on component materials. The dissolution of polymer excipients can slow the release and permeation of protein therapeutics at the administration site and thereby delay absorption. The understanding of drug penetration through different skin layers, its absorption into blood capillaries or lymphatics, and dermal metabolism remains limited. Additionally, the effects of these processes on the differences in pharmacokinetic profiles of proteins following intradermal microneedle administration are not well understood. Greater insights are required for the development of the next generation of intradermal microneedle biotherapeutics.

The role of initial lymphatics in the absorption of monoclonal antibodies after subcutaneous injection

The subcutaneous injection is the most common method of administration of monoclonal antibodies (mAbs) due to the patient's comfort and cost-effectiveness. However, the available knowledge about the transport and absorption of this type of biotherapeutics after subcutaneous injection is limited. Here, a mathematical framework to study the subcutaneous drug delivery of mAbs from injection to lymphatic uptake is presented. A poro-hyperelastic model of the tissue is exploited to find the biomechanical response of the tissue together with a transport model based on an advection-diffusion equation in large-deformation poro-hyperelastic Media. The process of mAbs transport to the lymphatic system has two major parts. First is the initial phase, where mAbs are dispersed in the tissue due to momentum exerted by injection. This stage lasts for only a few minutes after the injection. Then there is the second stage, which can take tens of hours, and as a result, mAb molecules are transported from the subcutaneous layer towards initial lymphatics in the dermis to enter the lymphatic system. In this study, we investigate both stages. The process of plume formation, interstitial pressure, and velocity development is explored. Then, the effect of the injection delivery parameters, injection site, and sensitivity of long-term lymphatic uptake due to variability in permeability, diffusivity, viscosity, and binding of mAbs are investigated. Finally, we study two different injection scenarios with variable injection volume and drug concentration inside the syringe and evaluate them based on the rate of lymphatic uptake. We use our results to find an equivalent lymphatic uptake coefficient similar to the coefficient widely used in pharmacokinetic (PK) models to study the absorption of mAbs. Ultimately, we validate our computational model against available experiments in the literature.

Understanding the interaction forces between shield-triggered autoinjectors and skin: an in-depth noninvasive study

OBJECTIVE

This noninvasive study aimed to understand the interaction between shield-triggered autoinjectors (AI) and skin at the point of activation, hypothesizing that the AI's housing absorbs a significant amount of the user-applied force depending on shield design and skin characteristics.

METHODS

Twenty-seven volunteers used a test device measuring applied force versus shield force and indentation depth relative to shield length (2,4,6,8 mm) in standing and sitting positions.

RESULTS

Significant differences were found between applied and shield force for the different shield lengths. Shorter shields resulted in significantly lower force transfer coefficients, with means ranging from 0.72 for the 2 mm shield to 0.94 for the 8 mm shield. ANOVA revealed statistically significant factors (p < .05), including position and gender, with females generally having lower coefficient values. Indentation depth increased with higher forces and varied significantly between positions without significant shield length impact.

CONCLUSION

The findings confirm that an increase in shield length at the point of activation reduces skin friction with the housing, resulting in less force loss and a lower device activation force perceived by the user. Force loss can be further reduced by standing up. Understanding device-tissue interactions will support development of better AIs with fewer user failures.

Visualisation and quantification of subcutaneous injections of different volumes, viscosities and injection rates: An ex-vivo micro-CT study

The effects of subcutaneous (SC) injection parameters such as drug formulation volume, viscosity and injection rate on therapeutic performance and tolerability have not been established for any drug product. In this study four groups of SC injections were performed on fresh ex vivo minipig abdominal tissue samples, varying volume (0.5-1 mL), viscosity (1-11 cP) and rate (0.02-0.1 mL/s). Micro-CT provided high resolution (50 micron) imaging of the SC tissues before and after injection, enabling a detailed 3D visualisation and analysis of how both injection parameters and tissue microstructure influence spatial distribution of injectables. We found that volume was the only significant factor for spatial distribution of injectate within our design space, and there were no significant factors for tissue backpressure. Variability within test groups was typically greater than differences between group means. Accordingly, whilst the higher viscosity formulations consistently exhibited reduced spatial distribution, the sample size was not large enough to establish confidence in this result. Comparing our findings to clinical evidence, we conclude that injection site and depth are more likely to influence PK and bioavailability than volume, viscosity and rate within our experimental space.

A Risk-Based Assessment for Determining the Pharmacokinetic Comparability Requirements of Biologic-Device Combination Products Administered by Subcutaneous Injection

The development of new large molecule drug therapies along with the innovation of biologic-device combination products such as prefilled syringes, autoinjectors and pen injectors have significantly impacted the treatment of new diseases and has improved the process of administering parenteral medicines. To support the regulatory approval of a new biologic-device combination products or subsequent chemistry, manufacturing and control changes impacting a combination product, sponsor companies must thoroughly assess the potential impact to product quality, safety and efficacy. In this report, a risk-based process to determine the potential impact to product quality, safety, and efficacy as well as corresponding regulatory actions supporting a chemistry, manufacturing and control change is presented. The risk assessment includes the standardized assessment of a) chemistry, manufacturing and control risk factors, potential responses and appropriately weighted scoring; b) pharmacokinetic risk factors, potential responses and appropriately weighted scoring; and c) the use of a 2-dimensional risk grid to combine the chemistry, manufacturing and control risks and pharmacokinetic risks to provide a regulatory recommendation. Three case studies (two clinical case studies and a post-approval case study) are provided to demonstrate the assessment process and capabilities.

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.

Frequencies and predictors of subcutaneous and intraosseous injection with 4 epinephrine autoinjector devices

BACKGROUND

To prevent anaphylaxis-associated illness, intramuscular epinephrine injection is recommended. Subcutaneous injection may reduce efficacy, and intraosseous injection promotes morbidity. A few studies suggested that commercially available thigh epinephrine autoinjectors (EAIs) may induce subcutaneous/intraosseous injection in some adults.

OBJECTIVE

To estimate the subcutaneous/intraosseous-injection rates of 4 EAIs by comparing their needle lengths with the ultrasound-measured skin-to-muscle depth and skin-to-bone depth of the midthigh of adults with allergic diseases in a cross-sectional study and to determine patient factors that predict subcutaneous EAI injection.

METHODS

Thigh ultrasound was conducted in a convenience-recruited cohort with minimal and maximal compression to estimate the effect of EAI-induced compression. Subcutaneous/intraosseous-injection rates were estimated for Anapen (BioProject), EpiPen (Mylan), Jext (ALK), and Emerade (Medeca). Multivariate analyses for subcutaneous-injection risk were conducted with age, male/female sex, abdominal and thigh circumferences, and upper-arm skinfold thickness.

RESULTS

A total of 68 patients were recruited. Compression thinned the subcutaneous tissue and muscle by 1 and 9 mm, respectively, on average. Projected subcutaneous-injection rates with/without compression were high for Anapen (65%-66%), moderate for EpiPen and Jext (29%-38%), and lowest for Emerade (13%-21%). Compression introduced a small intraosseous-injection risk with Emerade (4%). Female sex predicted subcutaneous injection (odds ratio, 1.3-2.0; all P < .001). Depending on the EAI, 29% to 97% of women and 0% to 41% of men would be injected subcutaneously. Older men were at risk of intraosseous Emerade injection. Obesity-related variables predicted subcutaneous injection poorly.

CONCLUSION

Anapen was associated with high subcutaneous-injection rates. EpiPen and Jext were projected to provide intramuscular injection in all men without risk of intraosseous injection. Emerade yielded the lowest subcutaneous-injection rates in women. Compression largely affected the muscle.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02886468.

Towards more tolerable subcutaneous administration: Review of contributing factors for improving combination product design

Subcutaneous (SC) injections can be associated with local pain and discomfort that is subjective and may affect treatment adherence and overall patient experience. With innovations increasingly focused on finding ways to deliver higher doses and volumes (≥2 mL), there is a need to better understand the multiple intertwined factors that influence pain upon SC injection. As a priority for the SC Drug Development & Delivery Consortium, this manuscript provides a comprehensive review of known attributes from published literature that contribute to pain/discomfort upon SC injection from three perspectives: (1) device and delivery factors that cause physical pain, (2) formulation factors that trigger pain responses, and (3) human factors impacting pain perception. Leveraging the Consortium's collective expertise, we provide an assessment of the comparative and interdependent factors likely to impact SC injection pain. In addition, we offer expert insights and future perspectives to fill identified gaps in knowledge to help advance the development of patient-centric and well tolerated high-dose/high-volume SC drug delivery solutions.

Unveiling the language of scars: A patient-centric themed framework for comprehensive scar morphology

BACKGROUND

Scarring, a pervasive issue spanning across medical disciplines, lacks a comprehensive terminology for effective communication, patient engagement, and outcome assessment. Existing scar classification systems are constrained by specific pathologies, physician-centric features, and inadequately account for emerging technologies. This study refrains from proposing yet another classification system and instead revisits the foundational language of scar morphology through a theme analysis of primary patient complaints.

METHOD

Data encompassing five years of a high-volume scar practice was analysed. Primary complaints were aggregated into collective descriptors and further organized into theme domains. The resulting hierarchical map of presenting complaints revealed five key domains: Loss of Function, Contour, Texture, Vector, and Colour Presenting complaints were codified into 42 items, which were then categorised into 14 collective descriptor terms. The latter were in turn organised into five overarching themes.

RESULT

Loss of Function, accounting for 10% of primary concerns, signifies reduced function attributed solely to the scar. Contour, encompassing 41% of concerns, pertains to scar height, shape, and depth. Texture, representing 12% of concerns, denotes tactile variations such as hardness, roughness, and moisture. Vector, comprising 13% of concerns, refers to scar tissue tension and associated distortions. Colour, the concern in 24% of cases, encompasses variations in pigmentation, vascularity, and exogenous pigments.

DISCUSSION

Standardized terminology enhances patient care, communication, and research. This study underscores the fundamental question of "what bothers the patient," reviving a patient-centred approach to scar management. By prioritizing themes based on patient complaints, this study innovatively integrates function, aesthetics, and patient experience. In conclusion, this study pioneers a paradigm shift in scar management by presenting a patient-driven theme framework that offers a common language for healthcare professionals and patients. Embracing this language harmonizes scar treatment, fosters innovation, and transforms scars from silent reminders into stories of resilience and healing.

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.

Challenging the Norm: A Multidisciplinary Perspective on Intravenous to Subcutaneous Bridging Strategies for Biologics

The transition from intravenous (i.v.) to subcutaneous (s.c.) administration of biologics is a critical strategy in drug development aimed at improving patient convenience, compliance, and therapeutic outcomes. Focusing on the increasing role of model-informed drug development (MIDD) in the acceleration of this transition, an in-depth overview of the essential clinical pharmacology, and regulatory considerations for successful i.v. to s.c. bridging for biologics after the i.v. formulation has been approved are presented. Considerations encompass multiple aspects beginning with adequate pharmacokinetic (PK) and pharmacodynamic (i.e., exposure-response) evaluations which play a vital role in establishing comparability between the i.v. and s.c. routes of administrations. Selected key recommendations and points to consider include: (i) PK characterization of the s.c. formulation, supported by the increasing preclinical understanding of the s.c. absorption, and robust PK study design and analyses in humans; (ii) a thorough characterization of the exposure-response profiles including important metrics of exposure for both efficacy and safety; (iii) comparability studies designed to meet regulatory considerations and support approval of the s.c. formulation, including noninferiority studies with PK and/or efficacy and safety as primary end points; and (iv) comprehensive safety package addressing assessments of immunogenicity and patients' safety profile with the new route of administration. Recommendations for successful bridging strategies are evolving and MIDD approaches have been used successfully to accelerate the transition to s.c. dosing, ultimately leading to improved patient experiences, adherence, and clinical outcomes.

The Needle Shield Size and Applied Force of Subcutaneous Autoinjectors Significantly Influence the Injection Depth

BACKGROUND

This study examines how shield-triggered autoinjectors (AIs), for subcutaneous drug delivery, affect injection depth. It focuses on shield size and applied force, parameters that could potentially lead to inadvertent intramuscular (IM) injections due to tissue compression.

METHOD

A blinded ex-vivo study was performed to assess the impact of shield size and applied force on injection depth. Shields of 15, 20, and 30 mm diameters and forces from 2 to 10 N were investigated. The study involved 55 injections in three Landrace, Yorkshire, and Duroc (LYD) pigs, with injection depths measured with computed tomography (CT). An in-vivo study, involving 20 injections in three LYD pigs, controlled the findings, using fluoroscopy (FS) videos for depth measurement.

RESULTS

The CT study revealed that smaller shield sizes significantly increased injection depth. With a 15 mm diameter shield, 10 N applied force, and 5 mm needle protrusion, the injection depth exceeded the needle length by over 3 mm. Injection depth increased with higher applied forces until a plateau was reached around 8 N. Both applied force and size were significant factors for injection depth (analysis of variance [ANOVA], P < .05) in the CT study. The FS study confirmed the ex-vivo findings in an in-vivo setting.

CONCLUSIONS

The study demonstrates that shield size has a greater impact on injection depth than the applied force. While conducted in porcine tissue, the study provides useful insights into the relative effects of shield size and applied force. Further investigations in humans are needed to confirm the predicted injection depths for AIs.

A survey of FDA Approved Monoclonal Antibodies and Fc-fusion Proteins for Manufacturing Changes and Comparability Assessment

OBJECTIVE

Manufacturing changes occur commonly throughout stages of biologics development and may result in product quality attribute changes. As changes in critical quality attributes have the potential to affect clinical safety and efficacy of products, it is imperative to ensure the quality and clinical performance before introducing the after-change products. Thus, we embarked on this project to understand what data have supported the manufacturing changes for licensed products with pre- and post-approval changes.

METHODS

We surveyed the manufacturing changes of 85 monoclonal antibodies and 10 Fc fusion proteins approved by the Food and Drug Administration as of December 25, 2021. After collecting the type and timing of changes for these products, we investigated the approaches that provided supporting data for the changes. The source documents included reports submitted by applicants and FDA's regulatory reviews.

RESULTS

Analytical comparability was assessed to support all identified manufacturing changes. Supporting clinical data were available in 92% of these manufacturing changes; including data from pharmacokinetic comparability studies alone (3%), other studies on efficacy or safety (70%) and a combination of both (19%). Clinical pharmacokinetic comparability data contributed to supporting substantial changes, such as host cell type or master cell bank changes, concentration or formulation changes, and changes from pre-filled syringes to autoinjectors, especially when introduced after completing pivotal studies.

CONCLUSION

Our comprehensive retrospective analysis provides an understanding of the regulatory experience and industry practice, which could facilitate developing appropriate comparability approaches to support manufacturing changes in the future.

Impact of Stoma Baseplate Convexity on Tension and Compression Around the Stoma Site: A Finite Element Analysis

For patients living with intestinal or urinary stomas, skin barriers play an essential role in protecting the peristomal skin and preventing peristomal complications. Convex baseplates press into the peristomal skin and are suitable for retracted stomas that do not protrude, peristomal skin with creases, folds, or dips, and stomas where frequent leaking can occur with flat pouching systems. However, there is a lack of data on the magnitude and location of tension applied to the abdomen by convex baseplates. We evaluated the impact of a range of convex baseplates applied to a simulated stoma site. A comparative finite element analysis investigation was conducted to evaluate the impact of eight different convex stoma system baseplates applied to an idealised flat abdomen, representing skin, subcutaneous tissue, and musculature layers. The baseplates considered had varying convexity with depths of 3.5 mm and 7 mm and internal structural diameters between ~30 mm and ~60 mm. The convex product range provided tension in the skin (maximum principal strain) and compression through the fat layer (minimum principal strain). Large differences in the locations and magnitudes of skin tension and fat layer compression were seen between the baseplates under analysis, with both the depth and diameter of convexity influencing the strain experienced across the abdominal topography. The results generated highlight the importance of having an appropriate range of convexity products available and selecting an appropriate option for use based on the stoma type and condition of the peristomal skin.

Unveiling Diabetes: Categories, Genetics, Diagnostics, Treatments, and Future Horizons

Diabetes mellitus is a global epidemic affecting millions of individuals worldwide. This comprehensive review aims to provide a thorough understanding of the categorization, disease identity, genetic architecture, diagnosis, and treatment of diabetes. The categorization of diabetes is discussed, with a focus on type 1 and type 2 diabetes, as well as the lesser-known types, type 3 and type 4 diabetes. The geographical variation, age, gender, and ethnic differences in the prevalence of type 1 and type 2 diabetes are explored. The impact of disease identity on disease management and the role of autoimmunity in diabetes are examined. The genetic architecture of diabetes, including the interplay between genotype and phenotype, is discussed to enhance our understanding of the underlying mechanisms. The importance of insulin injection sites and the insulin signalling pathway in diabetes management are highlighted. The diagnostic techniques for diabetes are reviewed, along with advancements for improved differentiation between types. Treatment and management approaches, including medications used in diabetes management are presented. Finally, future perspectives are discussed, emphasizing the need for further research and interventions to address the global burden of diabetes. This review serves as a valuable resource for healthcare professionals, researchers, and policymakers, providing insights to develop targeted strategies for the prevention, diagnosis, and management of this complex disease.

Addressing Insulin Injection Technique: A Follow-up Study of Canadian Patients with Diabetes

INTRODUCTION

Proper insulin injection technique is important for optimal glycaemic control, yet patients with diabetes often inject insulin incorrectly. Previous studies identified common errors in insulin injection in Canada, and this article seeks to evaluate the current insulin injection technique practices among patients and explore the effectiveness of feedback and education in improving their technique.

METHODS

The study recruited 147 patients and 16 physicians across Canada to gather insights into current insulin injection practices and education gaps. Eligible patients were people living with diabetes who inject insulin using an insulin pen and pen needles. Eligible physicians, who were unsupported by diabetes educators, completed a practice assessment survey and selected 10 eligible patients to complete a baseline assessment survey. During the patient visit, if an error in the patient's technique was identified, a pop-up knowledge transfer (KT) prompt would appear, providing feedback and information on best practices at the point of care. Follow-up surveys were completed 1-3 months later.

RESULTS

Physicians reported facing barriers to providing education and feedback, including lack of time and personnel, and lack of effective educational material. Patients demonstrated modest improvements in some injection technique domains at their follow-up visit, including injection force factors, time the needle was held in the skin, pen needle reuse, injection area size, and injection angle. The most common initial mistakes by patients were selecting an area smaller than recommended and not paying attention to the injection force. At the second visit, patients reduced an average of one error in their injection technique.

CONCLUSION

Results showed that basic feedback by their physician during one visit could exert moderate improvements on patients' injection technique. Proper injection technique is critical for diabetes management, and incorporating targeted ongoing education and support can significantly enhance physician practices, ultimately reducing risks and improving outcomes.

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.

Optimising Insulin Injection Techniques to Improve Diabetes Outcomes

The effectiveness of therapy in patients with diabetes depends on the correct use of the insulin injection technique. However, despite many established recommendations and evidence that an effective insulin injection technique is essential to improve glycaemic control and minimise the risk associated with diabetes, there is still a need to identify impediments to the insulin injection technique among patients and create awareness among patients and healthcare professionals about the importance of the optimisation of insulin injection techniques. This review focuses on the recent advancements in delivery devices, insulin injection technique teaching methods, monitoring, and complication management and highlights regional best practices and recommendations for optimising injection techniques to improve diabetes outcomes.

Machine Learning-Based Prediction of Abdominal Subcutaneous Fat Thickness During Pregnancy

Objective: Current evidence regarding the safety of abdominal subcutaneous injections in pregnant women is limited. In this study, we developed a predictive model for abdominal skin-subcutaneous fat thickness (S-ScFT) by gestational periods (GP) in pregnant women. Methods: A total of 354 cases were measured for S-ScFT. Three machine learning algorithms, namely deep learning, random forest, and support vector machine, were used for S-ScFT predictive modeling and factor analysis for each abdominal site. Data analysis was performed using SPSS and RapidMiner softwares. Results: The deep learning algorithm best predicted the abdominal S-ScFT. The common important variables in all three algorithms for the prediction of abdominal S-ScFT were menarcheal age, prepregnancy weight, prepregnancy body mass index (categorized), large fetus for gestational age, and alcohol consumption. Conclusion: Predicting the safety of subcutaneous injections during pregnancy could be beneficial for managing gestational diabetes mellitus in pregnant women.

Ultrasound Detected Subcutaneous Changes in a Pediatric Cohort After Initiation of a New Insulin Pump or Glucose Sensor

Objective: This study examined subcutaneous tissue changes at sites used by continuous subcutaneous insulin infusion (CSII) and continuous glucose monitoring (CGM), and tested whether these changes, if any, were associated with glycated hemoglobin (HbA1c). Research Design and Methods: This prospective study investigated recently used CSII or CGM sites in 161 children and adolescents during the first year after initiation of a new diabetes device. Subcutaneous changes such as echogenicity, vascularization, and the distance from the skin surface to the muscle at CSII and CGM sites were assessed by ultrasound. Results: The distance from skin surface to muscle fascia at both the upper arm and abdomen was influenced by age, body mass index z-score, and sex. Especially in boys and the youngest, the depth of many devices outreached the mean distance. The mean distance for boys at the abdomen and upper arm ranged from 4.5-6.5 mm and 5-6.9 mm for all ages, respectively. Hyperechogenicity at CGM sites was 4.3% after 12 months. The frequency of subcutaneous hyperechogenicity and vascularization at CSII sites increased significantly over time (41.2% to 69.3% and 2% to 16% respectively, P < 0.001 and P = 0.009). Hyperechogenicity in the subcutis was not a predictor of elevated HbA1c (P = 0.11). Conclusion: There is large variation in the distance from the skin surface to the muscle fascia and many diabetes devices reach even deeper. Hyperechogenicity and vascularization increased significantly over time at CSII sites, but not CGM sites. The importance of hyperechogenicity for insulin absorption is unclear and further investigations are needed. Clinical Trial Registration number: NCT04258904.

Needlestick Injuries With Insulin Injections: Risk Factors, Concerns, and Implications of the Use of Safety Pen Needles in the Asia-Pacific Region

Globally, health care workers (HCWs) are at a high risk of occupational exposure to needlestick injuries (NSIs). Needlestick injuries not only are associated with an increased risk of infections caused by bloodborne pathogens but are also a primary source of emotional distress and job burnout for HCWs and patients. Insulin injection-related NSIs are common among HCWs working in hospitals in the Asia-Pacific (APAC) region and impose a significant burden. Insulin pen needles have a high risk of transmitting infections (at both the patient-end and cartridge end of the sharp) after use. Recapping a needle after administering an insulin injection poses a major risk to HCWs. Currently, several safety-engineered needle devices (SENDs) are available with active or passive safety mechanisms. Passive insulin safety pen needles with dual-ended protection and automatic recapping capabilities have resulted in a significant drop in accidental punctures to HCWs while administering insulin to patients with diabetes. In this article, we have reviewed the burden and common causes of NSIs with insulin injections among HCWs in the APAC region. We have discussed current approaches to address the issues associated with NSIs and the benefits of introducing SENDs in health care settings, including long-term care facilities, nursing homes, and home care settings where patients may require assisted insulin injections. This review also summarizes key strategies/recommendations to prevent NSIs in HCWs and patients with diabetes in the APAC region.

Type 1 diabetes management in a competitive athlete: A five-year case report

Type I diabetes has an incidence of 15 per 100,000 people. Though it is a metabolic disorder, it can be seen in top, even professional athletes. Physical activity is recommended to manage diabetes, but there is a lack of specific knowledge on diabetes management and exercise from dedicated medical staff. This bias leads to suboptimal diabetes management, causing frequent hyper and hypoglycemia, a dysregulation of glycated hemoglobin, blood glucose out of control, and consequent needs to often intervene with extra insulin or carbohydrates. For 5 years, we followed a highly competitive male Caucasian athlete Vovinam Viet Vo Dao, with type I diabetes, aged 17. We monitored his glycated hemoglobin, the insulin drug administered, and glycemia blood level averages. We obtained, over time, a decrease in glycated hemoglobin by almost -22% and insulin administered by -37.33%, and average blood glycemia levels diminished by almost -27%. In addition, we carried out bioimpedance analysis and stratigraphy on the abdomen. Federation trainers supervised all physical training; we recorded an improvement in the general condition, underlined in particular by an increase in phase angle (from bioimpedance) of +17%.

Solute Transport across the Lymphatic Vasculature in a Soft Skin Tissue

Convective transport of drug solutes in biological tissues is regulated by the interstitial fluid pressure, which plays a crucial role in drug absorption into the lymphatic system through the subcutaneous (SC) injection. In this paper, an approximate continuum poroelasticity model is developed to simulate the pressure evolution in the soft porous tissue during an SC injection. This poroelastic model mimics the deformation of the tissue by introducing the time variation of the interstitial fluid pressure. The advantage of this method lies in its computational time efficiency and simplicity, and it can accurately model the relaxation of pressure. The interstitial fluid pressure obtained using the proposed model is validated against both the analytical and the numerical solution of the poroelastic tissue model. The decreasing elasticity elongates the relaxation time of pressure, and the sensitivity of pressure relaxation to elasticity decreases with the hydraulic permeability, while the increasing porosity and permeability due to deformation alleviate the high pressure. An improved Kedem-Katchalsky model is developed to study solute transport across the lymphatic vessel network, including convection and diffusion in the multi-layered poroelastic tissue with a hybrid discrete-continuum vessel network embedded inside. At last, the effect of different structures of the lymphatic vessel network, such as fractal trees and Voronoi structure, on the lymphatic uptake is investigated. In this paper, we provide a novel and time-efficient computational model for solute transport across the lymphatic vasculature connecting the microscopic properties of the lymphatic vessel membrane to the macroscopic drug absorption.

Investigation of appropriate needle length considering skin thickness with the real injection posture for insulin injections in diabetic patients

BACKGROUND

Insulin treatment is widely used not only for type 1 but also for type 2 diabetes patients. Insulin must be injected into the subcutaneous tissue to be effective. The needle length has been shortened for safety and efficiency. However, whether patients use an appropriate needle length is unclear.

METHODS

Skin thickness was measured by ultrasound with patients in their usual posture during injection. Furthermore, the effect of the intervention in which the needle length was changed was investigated.

RESULTS

Thirty-eight percent of the patients had fluid leakage and injected the needle intradermally. The average skin thickness was 3.3 mm while sitting, which was greater than that in a previous report including measurements taken while lying down. Consequently, the skin thickness was > 4 mm in 9.5% of the patients who used 4-mm needles. Cases of leakage and intradermal injection decreased when the needle length was changed.

CONCLUSIONS

This study identified that the needle length should be considered in patients with thick skin or a lower body mass index due to possibility of intradermal injection.

Implantable device with magnetically rotating disk for needle-free administrations of emergency drug

Prompt administration of first-aid drugs can save lives during medical emergencies such as anaphylaxis and hypoglycemia. However, this is often performed by needle self-injection, which is not easy for patients under emergency conditions. Therefore, we propose an implantable device capable of on-demand administration of first-aid drugs (i.e., the implantable device with a magnetically rotating disk [iMRD]), such as epinephrine and glucagon, via a noninvasive simple application of the magnet from the outside skin (i.e., the external magnet). The iMRD contained a disk embedded with a magnet, as well as multiple drug reservoirs that were sealed with a membrane, which was designed to rotate at a precise angle only when the external magnet was applied. During this rotation, the membrane on a designated single-drug reservoir was aligned and torn to expose the drug to the outside. When implanted in living animals, the iMRD, actuated by an external magnet, delivers epinephrine and glucagon, similar to conventional subcutaneous needle injections.

The Evolution of Diabetes Technology - Options Towards Personalized Care

Advances in diabetes technology, especially in the last few decades, have transformed our ability to deliver care to persons with diabetes (PWD). Developments in glucose monitoring, especially continuous glucose monitoring systems (CGM), have revolutionized diabetes care and empowered our patients to manage their disease. CGM has also played an integral role in advancing automated insulin delivery systems. Currently available and upcoming advanced hybrid-closed loop systems aim to decrease patient involvement and are approaching the functionality of a fully automated artificial pancreas. Other advances, such as smart insulin pens and daily patch pumps, offer more options for patients and require less complicated and costly technology. Evidence to support the role of diabetes technology is growing, and PWD and clinicians must choose the right type of technology with a personalized strategy to manage diabetes effectively. Here, we review currently available diabetes technologies, summarize their individual features and highlight key patient factors to consider when creating a personalized treatment plan. We also address current challenges and barriers to the adoption of diabetes technologies.

Motor point heatmap guide for neuromuscular electrical stimulation of the quadriceps muscle

PURPOSE

To create an anatomical chart that indicates the probability of finding a motor point (MP) in different areas of the quadriceps muscle.

METHODS

On 31 healthy adults, the individual anatomy of the vastus medialis (VM), rectus femoris (RF) and vastus lateralis (VL) was determined using ultrasound. Thereafter, a 3 Hz neuromuscular electrical stimulation (NMES) MP-search with a MP-pen was performed. The thigh anatomy was normalized and divided into 112 (8x14) 3x3cm areas, and the probability of finding a MP in the different areas was calculated to create a MP heat-map.

RESULTS

The heat-map displayed the two best 3x3cm areas, over VL and VM respectively, each with a probability greater than 50% of finding a MP and a higher probability compared to all other areas (p <.05). RF exhibited two areas with a 29% probability of finding a MP. A higher number of MPs on the quadriceps, mean (±SD) 9.4 ± 1, was in regression analysis found to be significantly associated with two independent factors higher physical activity level and lower body fat (R² = 0.42, p=<.0001).

CONCLUSION

Large inter-individual variations in location, and number of MPs were found, but the heat-map displayed areas with higher probability of finding a MP and can be used to facilitate NMES-application.

Imaging of large volume subcutaneous deposition using MRI: exploratory clinical study results

Subcutaneous (SC) delivery is a preferred route of administration for biotherapeutics but has predominantly been limited to volumes below 3 mL. With higher volume drug formulations emerging, understanding large volume SC (LVSC) depot localization, dispersion, and impact on the SC environment has become more critical. The aim of this exploratory clinical imaging study was to assess the feasibility of magnetic resonance imaging (MRI) to identify and characterize LVSC injections and their effect on SC tissue as a function of delivery site and volume. Healthy adult subjects received incremental injections of normal saline up to 5 mL total volume in the arm and up to 10 mL in the abdomen and thigh. MRI images were acquired after each incremental SC injection. Post-image analysis was performed to correct imaging artifacts, identify depot tissue location, create 3-dimensional (3D) SC depot rendering, and estimate in vivo bolus volumes and SC tissue distention. LVSC saline depots were readily achieved, imaged using MRI, and quantified via subsequent image reconstructions. Imaging artifacts occurred under some conditions, necessitating corrections applied during image analysis. 3D renderings were created for both the depot alone and in relation to the SC tissue boundaries. LVSC depots remained predominantly within the SC tissue and expanded with increasing injection volume. Depot geometry varied across injection sites and localized physiological structure changes were observed to accommodate LVSC injection volumes. MRI is an effective means to clinically visualize LVSC depots and SC architecture allowing assessment of deposition and dispersion of injected formulations.Trial Registration: Not applicable for this exploratory clinical imaging study.

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.

Impact of Infusion Set Materials and Designs on the Subcutaneous Response in People With Diabetes: A Rapid Review of the Literature

Insulin infusion sets (IISs) are an integral and intricate part of continuous subcutaneous insulin infusion for subjects with type 1 diabetes, infusing insulin from pump to the subcutaneous space. Insulin infusion sets interface with the skin surface, the dermis, and the subcutaneous space and may be the cause of infusion failure due to biological events or mechanical problems. Novel IISs with extended wear time and anti-inflammatory properties to mitigate these issues are described in the literature although material-tissue interactions are poorly understood. This rapid review focuses on the impact of IIS materials and designs on the subcutaneous response in people with diabetes and includes literature identified in PubMed, Embase, and Cochrane databases. Twenty-one studies were identified for qualitative synthesis that encompassed a limited and heterogenic body of evidence including 10 clinical reports, six reviews, one case report, two abstracts, and two communications. Two clinical reports were randomized crossover studies. Reports on materials mostly compared steel versus polytetrafluoroethylene (Teflon) cannulas and suggested no substantial difference in tissue response to these materials. Reports on designs focused mostly on the angle of cannula insertion. To drive and improve research on extended wear and nonimmunogenic IISs, future studies should focus on material-tissue interaction as dedicated outcome measures, quantified with punch biopsy and imaging techniques such as ultrasound, optical coherence tomography, and confocal reflectance microscopy. Original studies are required to further a field too young for a systematic meta-analysis.

Needle Technology for Insulin Administration: A Century of Innovation

Innovations in syringe and pen needle (PN) technology over the last 100 years have led to important advances in insulin delivery for people with diabetes, paralleling the strides made in developing recombinant DNA human insulin and insulin analogs with varying onset and duration of action. In this review, the history of advances in insulin delivery is described, focusing on progress in syringe, needle, and PN technologies. The early glass and metal syringes that required sterilization by boiling have been replaced by disposable, single-use syringes or pens with clear labeling for precise insulin dosing. The early needles ranging in length from 19 to 26 mm that required manual sharpening against a whetstone have been replaced by syringe needles of 6 mm and PNs of 4 mm in length as slender as 34 gauge. Imaging studies using ultrasound and computed tomography measured the thickness of skin and subcutaneous tissue layers to show feasibility of targeted insulin administration with shorter needles. These developments, coupled with innovations in needle/PN wall and tip structure, have led to improved injection experience for people with diabetes. It is also important to acknowledge the role of injection technique education, together with these advances in injection technology, for improving clinical outcomes and patient satisfaction. With continued projected growth of diabetes prevalence, particularly in developing countries where expensive and complex insulin delivery systems may not be practical, insulin syringes and pens will continue to serve as reliable and cost-effective means of insulin delivery for people with diabetes.

Implantable device actuated by manual button clicks for noninvasive self-drug administration

Self-injectable therapy has several advantages in the treatment of metabolic disorders. However, frequent injections with needles impair patient compliance and medication adherence. Therefore, we develop a fully implantable device capable of on-demand administration of self-injection drugs via noninvasive manual button clicks on the outer skin. The device is designed to infuse the drug only at the moment of click actuation, which allows for an accurate and reproducible drug infusion, and also prevents unwanted drug leakage. Using a mechanical means of drug infusion, this implantable device does not contain any electronic compartments or batteries, making it compact, and semi-permanent. When tested in animals, the device can achieve subcutaneous injection-like pharmacokinetic and pharmacodynamic effects for self-injection drugs such as exenatide, insulin, and glucagon.

Advances in Photoplethysmography for Personalized Cardiovascular Monitoring

Photoplethysmography (PPG) is garnering substantial interest due to low cost, noninvasiveness, and its potential for diagnosing cardiovascular diseases, such as cardiomyopathy, heart failure, and arrhythmia. The signals obtained through PPG can yield information based on simple analyses, such as heart rate. In contrast, when accompanied by the complex analysis of sophisticated signals, valuable information, such as blood pressure, sympathetic nervous system activity, and heart rate variability, can be obtained. For a complex analysis, a better understanding of the sources of noise, which create limitations in the application of PPG, is needed to get reliable information to assess cardiovascular health. Therefore, this Special Issue handles literature about noises and how they affect the waveform of the PPG caused by individual variations (e.g., skin tone, obesity, age, and gender), physiology (e.g., respiration, venous pulsation, body site of measurement, and body temperature), and external factors (e.g., motion artifact, ambient light, and applied pressure to the skin). It also covers the issues that still need to be considered in each situation.

Transport and distribution of biotherapeutics in different tissue layers after subcutaneous injection

The subcutaneous injection is the main route of administration for monoclonal antibodies (mAbs) and several other biotherapeutics due to the patient comfort and cost-effectiveness. However, their transport and distribution after subcutaneous injection is poorly understood. Here, we exploit a three-dimensional poroelastic model to find the biomechanical response of the tissue, including interstitial pressure and tissue deformation during the injection. We quantify the drug concentration inside the tissue. We start with a single-layer model of the tissue. We show that during injection, the difference between the permeability of the solvent and solute will result in a higher drug concentration proportional to the inverse permeability ratio. Then we study the role of tissue layered properties with primary layers, including epidermis, dermis, subcutaneous (SQ), and muscle layers, on tissue biomechanical response to injection and drug transport. We show that the drug will distribute mainly in the SQ layer due to its lower elastic moduli. Finally, we study the effect of secondary tissue elements like the deep fascia layer and the network of septa fibers inside the SQ tissue. We use the Voronoi algorithm to create random geometry of the septa network. We show how drugs accumulate around these tissue components as observed in experimental SQ injection. Next, we study the effect of injection rate on drug concentration. We show how higher injection rates will slightly increase the drug concentration around septa fibers. Finally we demonstrate how the concentration dependent viscosity will increase the concentration of biotherapeutics in the direction of septa fibers. .

Barriers and facilitators to insulin treatment: a phenomenological inquiry

BACKGROUND

Despite being the most effective treatment for advanced type 2 diabetes, the choice to start and maintain insulin therapy is based on a variety of criteria, including the patients' acceptance and willingness to adhere to it. The patients' beliefs and experiences, on the other hand, could not be revealed without a thorough exploration.

OBJECTIVES

This study investigated the barriers and facilitators to insulin treatment from the perspectives of patients with type 2 diabetes following treatment at Dessie Comprehensive Specialized Hospital, North-East Ethiopia.

METHODS

A phenomenological study was conducted from July 2019 to January 2020. Twenty-four (11 males and 13 females) participants were recruited purposively. Data were collected through face-to-face in-depth interviews, lasted about 23 to 71 min, until theoretical saturation was reached, and then organized using QDA Miner Lite v2.0.9. The transcripts were thematically analyzed using narrative strategies and the themes that arose were discussed in detail.

RESULTS

The most common facilitator of insulin treatment was its relative effectiveness, which was followed by its convenience (fewer gastrointestinal side effects, small needle size and ease of use), the concept of it is life, faith in doctors' decisions, family support, and health insurance membership. The most common impediments, on the other hand, were market failures (expensiveness and supply shortages), followed by its properties and patients' circumstances.

CONCLUSIONS

Market failures due to supply shortages and associated costs were identified to be the most significant barriers to insulin treatment, necessitating the availability of an effective pharmaceutical supply management strategy that targets on insulin supply and affordability. It is also strongly recommended that health insurance coverage be increased.

Repeated insulin injection without site rotation affects skin thickness - ultrasonographic and histological evaluation

AIMS/INTRODUCTION

The influence of repeated insulin injection on subcutaneous tissue is known, but its impact on the skin is unclear. Therefore, this study aimed to elucidate the impact of repeated insulin injections on the skin.

MATERIAL AND METHODS

The properties of the skin and the subcutaneous tissue were evaluated in 52 insulin-treated adult patients with diabetes with abnormal findings at the site of self-injection (36 with subcutaneous nodules, 16 with suspected subcutaneous tissue induration) by ultrasonography. In all subjects, both normal and abnormal areas were examined. In addition, skin biopsies were performed in four subjects.

RESULTS

The skin thickness of the normal and abnormal skin sites was 1.95 (1.60, 2.50) and 2.80 (2.27, 3.30) mm, respectively (median (first quartile, third quartile)), (P < 0.001). The biopsy specimens revealed slightly thickened and tight bundles of collagen in the dermis. Three patients had amyloid deposits in the subcutaneous tissue, and one also showed these in the dermis. These were positively stained for insulin antibody.

CONCLUSIONS

Repeated insulin injection procedures result in skin thickening. Increased collagen fibers and possibly amyloid deposition in the dermis may be involved. The results reaffirmed the importance of appropriate site rotation in insulin injection and revealed the usefulness of ultrasonographic skin examination in evaluating the self-injection procedure.

A comparison of imaging techniques to measure skin flap thickness in cochlear implant patients to enable pre-operative device selection

OBJECTIVES

Magnetic resonance imaging (MRI)-compatible cochlear implants have weaker internal magnets than non-MRI-compatible devices. Their suitability for individual patients is limited by skin flap thickness, traditionally measured with a needle in the operating theatre. We aimed to establish the accuracy of imaging modalities to measure skin flap thickness pre-operatively, with the goal of streamlining device selection and simplifying the consent process.

METHODS

Skin flap measurements were taken using ultrasound (US), computed tomography (CT) and MRI and compared for agreement with intra-operative needle measurement.

RESULTS

Twenty-seven skin flaps were included. Absolute agreement between needle and imaging methods was low: needle/US: 44.4% (95% confidence interval [CI]: 27.7-62.7), needle/CT: 39.1% (95% CI: 22.2-59.2), needle/MRI: 20.8% (95% CI: 9.2-40.5). However, US and CT showed 95.7% agreement (95% CI: 76.0-99.8) with intraclass correlation of 0.996 (95% CI: 0.991-0.998) and narrow Bland-Altman limits of agreement (-0.37, 0.45 mm). BMI and skin flap thickness showed a significant positive correlation (r_s= 0.664, P = 0.002) but no significant correlation was observed for age (P = 0.659).

DISCUSSION

The high level of agreement between US and CT suggests that there are more accurate measurements of skin flap thickness compared with needle or MRI. Needle measurements are consistently smaller.

CONCLUSION

The use of CT or US should be considered when making pre-operative device choices.

Skin optical properties in the obese and their relation to body mass index: a review

SIGNIFICANCE

Obesity is a worldwide epidemic contributing directly to several cardiovascular risk factors including hypertension and type 2 diabetes. Wearable devices are becoming better at quantifying biomarkers relevant for the management of health and fitness. Unfortunately, both anecdotal evidence and recent studies indicate that some wearables have higher levels of error when utilized by populations with darker skin tones and high body mass index (BMI). There is an urgent need for a better evaluation of the limits of wearable health technologies when used by obese individuals.

AIMS

(1) To review the current know-how on changes due to obesity in the skin epidermis, dermis, and subcutis that could affect the skin optical properties; (2) for the green wavelength range, to evaluate the difference in absorption and scattering coefficients from the abdominal skin between individuals with and without elevated BMI. The changes include alterations in layer thickness and cell size, as well as significant differences in chromophores and scatterer content, e.g., water, hemoglobin, collagen, and lipids.

APPROACH

We have summarized literature pertaining to changes in skin and its components in obesity and report the results of our search using articles published between years 1971 and 2020. A linear model was used to demonstrate the absorption and reduced scattering coefficient of the abdominal skin of individuals with and without elevated BMI in the green wavelength range (530 to 550 nm) that is typically found in most wearables.

RESULTS

The general trends indicate a decrease in absorption for both dermis and subcutis and an increase in reduced scattering for both epidermis and dermis. At 544-nm wavelength, a typical wavelength used for photoplethysmography (PPG), the absorption coefficient's relative percentage difference between high and low BMI skin, was 49% in the subcutis, 19% in the dermis, and negligible in the epidermis, whereas the reduced scattering coefficient relative difference was 21%, 29%, and 165% respectively.

CONCLUSIONS

These findings suggest that there could be significant errors in the output of optical devices used for monitoring health and fitness if changes due to obesity are not accounted for in their design.

Implications of obesity for drug administration and absorption from subcutaneous and intramuscular injections: A primer

DISCLAIMER

In an effort to expedite the publication of articles related to the COVID-19 pandemic, AJHP is posting these manuscripts online as soon as possible after acceptance. Accepted manuscripts have been peer-reviewed and copyedited, but are posted online before technical formatting and author proofing. These manuscripts are not the final version of record and will be replaced with the final article (formatted per AJHP style and proofed by the authors) at a later time.

PURPOSE

To discuss the potential implications of obesity for drug administration and absorption from subcutaneous (SC) and intramuscular (IM) injection sites.

SUMMARY

The SC and IM routes are useful for the parenteral administration of medications to optimize pharmacokinetic properties such as time to onset and duration of effect, for cost considerations, or for ease of administration, such as when intravenous access is unavailable. The choice of SC or IM injection depends on the specific medication, with SC administration preferred for products such as insulin where a slower and more sustained response is desirable, while IM administration is usually preferred for products such as vaccines where more rapid absorption leads to a more rapid antibody response. Obesity has the potential to influence the rate and extent of absorption, as well as adverse effects, of medications administered by the SC or IM route through changes in SC tissue composition and depth or by inadvertent administration of IM medications into SC tissue because of improper needle length. Potential adverse effects associated with IM or SC injections in addition to pain, bruising, and hematoma formation include sciatic nerve injury, particularly with IM injection in the upper outer quadrant of the buttock; bone contusion or rarely osteonecrosis if the IM injection is excessively deep; and granulomas, fat necrosis, and calcification with SC injection.

CONCLUSION

Issues related to medication absorption in obese patients are likely to become more prominent in the future with increasing approvals of a wide range of biotherapeutic agents administered by SC injection. Studies should be directed toward these and other agents to assist with dosing decisions in this challenging population.

Population Pharmacokinetics of Tanezumab Following Intravenous or Subcutaneous Administration to Patients with Osteoarthritis or Chronic Low Back Pain

AIMS

Describe population pharmacokinetics of intravenous (IV) and subcutaneous (SC) tanezumab across Phase 2b/3 studies of osteoarthritis (OA) and chronic low back pain (CLBP). Methods Data from 10 studies of IV or SC tanezumab (2.5-20 mg every 8 weeks for up to 56 weeks) were included in a multi-step analysis. In Step 1, a two-compartment model with linear and non-linear elimination (based on prior analysis of pre-2015 IV osteoarthritis studies) was expanded to include other pre-2015 studies. In Step 2, post-2015 SC studies were combined into the model. Steps 3 and 4 evaluated impact of baseline nerve growth factor (NGF) and treatment-emergent anti-drug antibodies (TE ADA).

RESULTS

SC bioavailability was estimated at 62-76%. The key disposition parameters CL, V_c , V_p , and KM were estimated to be 0.133 L·day^-1 , 2.6 L, 1.77 L and 31.2 μg·L^-1 . Plasma tanezumab concentration was predicted to reach C_max at 8.9- 11.2 days following single and multiple SC administration in typical patients within the dose range of SC Phase 3 studies (2.5-10 mg every 8 weeks). Exposure of a typical patient was similar between IV and SC for the second part of the dosing interval (weeks 4-8). Covariates selected on the absorption parameters were WT, age, sex, and injection site. Baseline NGF had minimal effect on maximum elimination capacity and TE ADA status was associated with slightly higher tanezumab clearance (6-7%).

CONCLUSION

Our model adequately described plasma tanezumab concentration versus time following IV or SC administration. WT was the most influential covariate with respect to absorption of tanezumab in comparison to patient population (OA and CLBP) or other demographics. There was no clinically relevant effect of baseline NGF or TE ADA on tanezumab PK.

Reduction of bleeding complications on puncture site after percutaneous coronary intervention using a 6.5-French sheathless guiding catheter

BACKGROUND

Reducing complications at the puncture site after percutaneous coronary intervention (PCI) is important. The diameter of a 6.5-French (Fr) sheathless guiding catheter (GC) is smaller by approximately 2-Fr compared to a 6-Fr conventional sheath. In the present study, we investigated the post-PCI puncture site complications of a transradial approach in each gender while using a 6.5-Fr sheathless GC.

METHODS AND RESULTS

Our study consisted of 332 patients who underwent transradial coronary intervention (TRI) between August 2017 and July 2019. We classified the patients into either the 6.5-Fr sheathless GC (Asahi, Intecc, Aichi, Japan) Group (Sheathless group: n = 182 males, 58 females) or the 6-Fr sheathed GC Group (Sheathed group: n = 150 males, 36 females). We determined the complications at the puncture site: oozing, subcutaneous hemorrhage, formation of hematoma, pseudoaneurysms, and peripheral neuropathy. The body mass index of the patients was greater in the sheathless GC group compared to the sheathed GC group (24.5 ± 3.5 kg/m² vs. 23.6 ± 3.7 kg/m², p = 0.02). In males, there was no significant difference in the complication rate at the puncture site between the sheathless GC and sheathed GC groups (19.3% vs. 18.6%, p = 0.88). However, the complication rate at the puncture site in females was higher in the sheathed GC group than in the sheathless GC group (36% vs. 15.5%, p = 0.02). A multiple logistic regression analysis revealed that the use of a 6.5-Fr sheathless GC independently reduced the complications in female patients (p = 0.006).

CONCLUSION

The use of the 6.5-Fr sheathless GC system in a transradial approach reduced the complications at the puncture site in female patients. The 6.5-Fr sheathless GC system may be a safe option for them compared to the conventional sheath system.

Abdominal skin subcutaneous fat thickness over the gestational period in Korean pregnant women: a descriptive observational study

Purpose

Although insulin is usually injected into the abdominal subcutaneous fat, in pregnancy women tend to avoid abdominal injections due to concern about fetal damage. Prior studies have been limited to only measuring skin-subcutaneous fat thickness (S-ScFT) at one site at specific pregnancy points. This study aimed to measure S-ScFT across several abdominal sites and over the gestational period in Korean pregnant women. This can identify which site would be relatively safe for subcutaneous injection during pregnancy.

Methods

Healthy women over 24 weeks of pregnancy in Korea were invited to voluntarily participate in this descriptive study. For the 142 women, S-ScFT of 12 sites in the abdomen were measured by ultrasound, several times over the pregnancy. Each incidence was treated as a case and a total of 262 cases were analyzed.

Results

The mean S-ScFT during pregnancy was 1.14±0.47 cm (1.25±0.54 cm at 24⁺⁰–27⁺⁶ weeks; 1.17±0.48 cm at 28⁺⁰–31⁺⁶ weeks; 1.09⁺⁰.40 cm at 32⁺⁰–35⁺⁶ weeks; and 1.06±0.47 cm at 36⁺⁰–40 weeks of pregnancy). Most S-ScFT were thicker than 10 mm. But S-ScFTs in the lateral abdomen and some sites were suboptimal (<6 mm), especially in the pre-pregnancy underweight body mass index group, who had a high rate of suboptimal thickness (27.1% overall and 33.9% in the lateral side).

Conclusion

The whole abdomen seems to be appropriate for subcutaneous injection in most Korean women during pregnancy, with a 4 to 5-mm short needle. However, for the lateral abdomen, making the skin fold might be needed for fetal safety.

Novel cannula design improves large volume auto-injection rates for high viscosity solutions

A prototype reusable large-volume (2 mL) autoinjector (LVAI) was designed to compare injection performance of a novel 27 gauge ultra-thin wall (UTW) pre-filled syringe (PFS) cannula (8 mm external cannula length, 14.4 mm total needle length) against an existing 27 gauge special thin wall (STW) PFS cannula (12.7 mm external cannula length, 19 mm total needle length) across a range of injectate viscosities (2.3–30 cP) in a series of in vivo feasibility studies in swine. The UTW cannula had an approximately 30% greater cross-sectional lumen area than the STW cannula. The target exposed needle length was adjusted to ensure appropriate needle penetration depth and achieve injectate deposition in the subcutaneous (SC) tissue. Delivery time and volume, injection site leakage, injectate depot location, and local tissue effects were examined. The STW and UTW cannulae both provided effective SC delivery of contrast placebo solutions, and were able to accommodate injectate viscosity up to 30 cP without quantifiable leakage from the tissue and with minor tissue effects which resolved within 1–2 hours. Delivery times at each viscosity were significantly different between PFS types with the UTW PFS producing faster delivery times. In a histological substudy of the UTW cannula using injectate viscosities up to 50 cP, injection site reactions were rare and, when present, were of minimal severity. This series of studies demonstrates the feasibility of LVAI SC injection and informs autoinjector and PFS design considerations. Use of a UTW cannula may enable more rapid LVAI injections with minimal tissue effects, especially for higher viscosity formulations.

Hypoxia driven opioid targeted automated device for overdose rescue

Opioid use disorder has been designated a worsening epidemic with over 100,000 deaths due to opioid overdoses recorded in 2021 alone. Unintentional deaths due to opioid overdoses have continued to rise inexorably. While opioid overdose antidotes such as naloxone, and nalmefene are available, these must be administered within a critical time window to be effective. Unfortunately, opioid-overdoses may occur in the absence of antidote, or may be unwitnessed, and the rapid onset of cognitive impairment and unconsciousness, which frequently accompany an overdose may render self-administration of an antidote impossible. Thus, many lives are lost because: (1) an opioid overdose is not anticipated (i.e., monitored/detected), and (2) antidote is either not present, and/or not administered within the critical frame of effectiveness. Currently lacking is a non-invasive means of automatically detecting, reporting, and treating such overdoses. To address this problem, we have designed a wearable, on-demand system that comprises a safe, compact, non-invasive device which can monitor, and effectively deliver an antidote without human intervention, and report the opioid overdose event. A novel feature of our device is a needle-stow chamber that stores needles in a sterile state and inserts needles into tissue only when drug delivery is needed. The system uses a microcontroller which continuously monitors respiratory status as assessed by reflex pulse oximetry. When the oximeter detects the wearer’s percentage of hemoglobin saturated with oxygen to be less than or equal to 90%, which is an indication of impending respiratory failure in otherwise healthy individuals, the microcontroller initiates a sequence of events that simultaneously results in the subcutaneous administration of opioid antidote, nalmefene, and transmission of a GPS-trackable 911 alert. The device is compact (4 × 3 × 3 cm), adhesively attaches to the skin, and can be conveniently worn on the arm. Furthermore, this device permits a centralized remotely accessible system for effective institutional, large-scale intervention. Most importantly, this device has the potential for saving lives that are currently being lost to an alarmingly increasing epidemic.

Subcutaneous Administration: Evolution, Challenges, and the Role of Hyaluronidase

BACKGROUND

The subcutaneous (SC) route has evolved significantly. More than two dozen chemotherapy and supportive therapies have been approved for use in the oncology setting. Several IV therapies have been approved for the SC route and require a significantly higher volume than historical maximum limits. Differences exist in how these drugs are administered as compared to older chemotherapy agents.

OBJECTIVES

The purpose of this article is to provide a brief history of the SC route and describe its role in cancer treatment. The use of recombinant hyaluronidase is reviewed within the context of SC monoclonal antibodies. Proper administration techniques and interventions for reducing patient discomfort are discussed.

METHODS

Sentinel medical texts, pharmacokinetic studies, manufacturer's recommendations, and peer-reviewed articles were examined.

FINDINGS

The SC route offers several advantages over the oral and IV routes. A clear understanding of anatomical site selection and injection techniques is beneficial for providing requisite patient education.