Recent advances in transdermal insulin delivery technology: A review.

Transdermal drug delivery refers to the administration of drugs through the skin, after which the drugs can directly act on or circulate through the body to the target organs or cells and avoid the first-pass metabolism in the liver and kidneys experienced by oral drugs, reducing the risk of drug poisoning. From the initial singular approach to transdermal drug delivery, there has been a shift toward combining multiple methods to enhance drug permeation efficiency and address the limitations of individual approaches. Technological advancements have also improved the accuracy of drug delivery. Optimizing insulin itself also enables its long-term release via needle-free injectors. In this review, the diverse transdermal delivery methods employed in insulin therapy and their respective advantages and limitations are discussed. By considering factors such as the principles of transdermal penetration, drug delivery efficiency, research progress, synergistic innovations among different methods, patient compliance, skin damage, and posttreatment skin recovery, a comprehensive evaluation is presented, along with prospects for potential novel combinatorial approaches. Furthermore, as insulin is a macromolecular drug, insights gained from its transdermal delivery may also serve as a valuable reference for the use of other macromolecular drugs for treatment.

Needle-Free Jet Injection of Poly-(Lactic Acid) for Atrophic Acne Scars: Literature Review and Report of Clinical Cases.

Acne scars, particularly atrophic ones, present a persistent challenge in cosmetic medicine and surgery, requiring extended and multifaceted treatment approaches. Poly-(lactic acid) injectable fillers show promise in managing atrophic acne scars by stimulating collagen synthesis. However, the utilization of needle-free injectors for delivering poly-(lactic acid) into scars remains an area requiring further exploration. In this article, a summary of the latest advancements in needle-free jet injectors is provided, specifically highlighting the variations in jet-producing mechanisms. This summary emphasizes the differences in how these mechanisms operate, offering insights into the evolving technology behind needle-free injection systems. The literature review revealed documented cases focusing on treating atrophic acne scars using intralesional poly-(lactic acid) injections. The results of these clinical studies could be supported by separate in vitro and animal studies, elucidating the feasible pathways through which this treatment operates. However, there is limited information on the use of needle-free jet injectors for the intradermal delivery of poly-(lactic acid). Clinical cases of atrophic acne scar treatment are presented to explore this novel treatment concept, the needle-free delivery of poly-(lactic acid) using a jet pressure-based injector. The treatment demonstrated efficacy with minimal adverse effects, suggesting its potential for scar treatment. The clinical efficacy was supported by histological evidence obtained from cadaver skin, demonstrating an even distribution of injected particles in all layers of the dermis. In conclusion, we suggest that novel needle-free injectors offer advantages in precision and reduce patient discomfort, contributing to scar improvement and skin rejuvenation. Further comprehensive studies are warranted to substantiate these findings and ascertain the efficacy of this approach in scar treatment on a larger scale.

Dynamic behavior of a spring-powered micronozzle needle-free injector.

Conventional injection is still the leading method to deliver macromolecular therapeutics. Needle injection is considered a low compliance administration strategy, principally due to pain and needle phobia. This has fostered the research on the development of alternative strategies to circumvent the skin barrier. Among needle-free drug delivery methods, jet injection is an old strategy with great potential not yet completely disclosed. Here, the design, engineering and dynamic behavior of a novel spring-powered micronozzle needle-free injector is presented. Fluid mechanics was first studied in air to calculate jet force and speed as well as injection duration in different conditions. Polyacrylamide gel was used to simulate a soft tissue and to investigate the jet evolution over time of different injected doses. Finally, ex vivo characterization was carried out on pig skin. Results evidenced a direct dependence of the force, velocity, and duration with the injection volume. The model material allowed individuating the different steps of jet penetration and to attempt a mechanistic explanation. A different behavior has been recorded in the skin with interesting findings for subcutaneous and/or dermal delivery. Peculiar features with respect to existing jet injectors confers to this device good potentiality for a future clinical application.

Needle-free delivery of macromolecules through the skin using controllable jet injectors.

INTRODUCTION: Transdermal delivery of drugs has a number of advantages in comparison to other routes of administration. The mechanical properties of skin, however, impose a barrier to administration and so most compounds are administered using hypodermic needles and syringes. In order to overcome some of the issues associated with the use of needles, a variety of non-needle devices based on jet injection technology has been developed. AREAS COVERED: Jet injection has been used primarily for vaccine administration but has also been used to deliver macromolecules such as hormones, monoclonal antibodies and nucleic acids. A critical component in the more recent success of jet injection technology has been the active control of pressure applied to the drug during the time course of injection. EXPERT OPINION: Jet injection systems that are electronically controllable and reversible offer significant advantages over conventional injection systems. These devices can consistently create the high pressures and jet speeds necessary to penetrate tissue and then transition smoothly to a lower jet speed for delivery of the remainder of the desired dose. It seems likely that in the future this work will result in smart drug delivery systems incorporated into personal medical devices and medical robots for in-home disease management and healthcare.