Subcutaneous nicotine delivery via needle-free jet injection: A porcine model

Advancements in transdermal drug delivery: A comprehensive review of physical penetration enhancement techniques

Transdermal drug administration has grown in popularity in the pharmaceutical research community due to its potential to improve drug bioavailability, compliance among patients, and therapeutic effectiveness. To overcome the substantial barrier posed by the stratum corneum (SC) and promote drug absorption within the skin, various physical penetration augmentation approaches have been devised. This review article delves into popular physical penetration augmentation techniques, which include sonophoresis, iontophoresis, magnetophoresis, thermophoresis, needle-free injection, and microneedles (MNs) Sonophoresis is a technique that uses low-frequency ultrasonic waves to break the skin's barrier characteristics, therefore improving drug transport and distribution. In contrast, iontophoresis uses an applied electric current to push charged molecules of drugs inside the skin, effectively enhancing medication absorption. Magnetophoresis uses magnetic fields to drive drug carriers into the dermis, a technology that has shown promise in aiding targeted medication delivery. Thermophoresis is the regulated heating of the skin in order to improve drug absorption, particularly with thermally sensitive drug carriers. Needle-free injection technologies, such as jet injectors (JIs) and microprojection arrays, offer another option by producing temporary small pore sizes in the skin, facilitating painless and effective drug delivery. MNs are a painless, minimally invasive method, easy to self-administration, as well as high drug bioavailability. This study focuses on the underlying processes, current breakthroughs, and limitations connected with all of these approaches, with an emphasis on their applicability in diverse therapeutic areas. Finally, a thorough knowledge of these physical enhancement approaches and their incorporation into pharmaceutical research has the potential to revolutionize drug delivery, providing more efficient and secure treatment choices for a wide range of health-related diseases.

Experimental investigation of the optimal driving pressure for a larger-volume controllable jet injection system

Jet injection technology has become the alternative drug delivery method of conventional needle-based injection due to its obvious advantages. In order to meet the demand for larger volume injection, the pneumatic jet injection systems have efficiently administrated vaccine up to 1 mL in human. Our recent study has also demonstrated that controlling the driving pressure enabled the pneumatic jet injection system to deliver larger volumes of drugs to target sites at desired rates and times. This work continues to explore the optimal two-phase driving pressure combination with better injection efficiency for typical larger-volume (1.0 mL) jet injection with controllable pneumatic jet injection system. Under the combination of a first phase driving pressure of 1.00 MPa and a second phase driving pressure ranging from 0.25 to 0.90 MPa, dynamic characteristics, dispersion characteristics and pharmacokinetic characteristics of this controllable jet injection system were quantitatively analyzed. In all experiments, it was confirmed that the optimal driving pressure combination of 1.0 mL ejection volume was close to (1.00-0.50) MPa. That is, the injection velocities of 151.85 m/s and 102.01 m/s for the first and second phase respectively facilitated better injection performance with a controlled release of 1.0 mL ejection volume. This strategy is practical for facilitating the clinical application of large-volume controllable jet injection systems.

Dynamic interaction of injected liquid jet with skin layer interfaces revealed by microsecond imaging of optically cleared ex vivo skin tissue model

BACKGROUND

Needle-free jet injection (NFJI) systems enable a controlled and targeted delivery of drugs into skin tissue. However, a scarce understanding of their underlying mechanisms has been a major deterrent to the development of an efficient system. Primarily, the lack of a suitable visualization technique that could capture the dynamics of the injected fluid-tissue interaction with a microsecond range temporal resolution has emerged as a main limitation. A conventional needle-free injection system may inject the fluids within a few milliseconds and may need a temporal resolution in the microsecond range for obtaining the required images. However, the presently available imaging techniques for skin tissue visualization fail to achieve these required spatial and temporal resolutions. Previous studies on injected fluid-tissue interaction dynamics were conducted using in vitro media with a stiffness similar to that of skin tissue. However, these media are poor substitutes for real skin tissue, and the need for an imaging technique having ex vivo or in vivo imaging capability has been echoed in the previous reports.

METHODS

A near-infrared imaging technique that utilizes the optical absorption and fluorescence emission of indocyanine green dye, coupled with a tissue clearing technique, was developed for visualizing a NFJI in an ex vivo porcine skin tissue.

RESULTS

The optimal imaging conditions obtained by considering the optical properties of the developed system and mechanical properties of the cleared ex vivo samples are presented. Crucial information on the dynamic interaction of the injected liquid jet with the ex vivo skin tissue layers and their interfaces could be obtained.

CONCLUSIONS

The reported technique can be instrumental for understanding the injection mechanism and for the development of an efficient transdermal NFJI system as well.

Duck plague virus infection alter the microbiota composition and intestinal functional activity in Muscovy ducks

Intestinal damage from the duck plague virus (DPV) infection affects intestinal inflammation factors expression and barrier dysfunction. Here we report findings from the pathogenicity of the intestinal tract, intestinal morphological, intestinal permeability, inflammatory cytokines, and tight junction gene expression in 72 two-wk-old Muscovy ducks exposed to DPV. The characterization of intestinal metabolites and their classification were examined using 16-sequencing technology. The primary outcomes of the study evaluated the correlation between intestinal microbiota characteristics and the degree of infected tissue. The secondary outcomes were to determine whether the biosignatures that defined the microbiota were positively or negatively correlated with viral infection. The tissue was infected accompanied a mild damage of liver and spleen, and severe intestinal bleeding. Two inoculation routes were constructed with susceptible animals to assess the pathogenicity of the DPV in order to enrich the status of infection in Muscovy ducks. High levels of virus titer from Muscovy ducks were found being in the intestine. The expression of INF-α and IL-β with viral infection increased at 4, and 6 dpi, respectively, after detecting of the inflammatory factor and barrier function genes. At 4 and 6 dpi, barrier function gene of ZO-1 and Occludin reduced. The severity of viral infection was significantly correlated with the characteristics of the intestinal microbiota. Ducks infected with the DPV had an increase in the phylum Firmicutes, a decrease in the phylum Actinobacteriota, and differential enrichment with the genus Bacteroides, Tyzzerella, Enterococcus, and Escherchia-Shigella, while the genus Rothia, Streptococcus, and Ralstonia were differentially enriched in the control group. The findings from the current study demonstrated that DPV infection leads to an imbalance of the intestinal microbiota and disruption of the microbial homeostasis in the intestinal tissue in ducks, which might be one of the mechanisms whereby DPV infection might be established in Muscovy ducks. Na⁺/K⁺-ATPase and Ca²⁺/Mg²⁺-ATPase activity monitoring also showed that viral infection reduced these activities. These findings imply that changes in intestinal microbiota, intestinal barrier gene expression, and inflammatory factor are related to viral infection. When taken as a whole, this work provides fresh perspectives on the characteristics of intestinal microbiota and the infection damage caused by the DPV.

Design and Analysis: Servo-Tube-Powered Liquid Jet Injector for Drug Delivery Applications

The current state of commercially available needle-free liquid jet injectors for drug delivery offers no way of controlling the output pressure of the device in real time, as the driving mechanism for these injectors provides a fixed delivery pressure profile. In order to improve the delivery efficiency as well as the precision of the targeted tissue depth, it is necessary to develop a power source that can accurately control the plunger velocity. The duration of a liquid jet injection can vary from 10 to 100 ms, and it generate acceleration greater than 2 g (where g is the gravity); thus, a platform for real-time control must exhibit a response time greater than 1 kHz and good accuracy. Improving the pioneering work by Taberner and others whereby a Lorentz force actuator based upon a voice coil is designed, this study presents a prototype injector system with greater controllability based on the use of a fully closed-loop control system and a classical three-phase linear motor consisting of three fixed coils and multiple permanent magnets. Apart from being capable of generating jets with a required stagnation pressure of 15–16 MPa for skin penetration and liquid injection, as well as reproducing typical injection dynamics using commercially available injectors, the novelty of this proposed platform is that it is proven to be capable of shaping the real-time jet injection pressure profile, including pulsed injection, so that it can later be tailored for more efficient drug delivery.

Clinical endpoints of needle-free jet injector treatment: An in depth understanding of immediate skin responses

Objectives

Needle‐free jet injectors have been used in dermatological practice for many years. However, predefined clinical endpoints that guide physicians to choose optimal device settings have not been clearly defined. Here, we evaluate immediate skin responses as clinical endpoints for needle‐free jet injector treatments.

Methods

We injected methylene blue in ex vivo human skin using an electronically‐controllable pneumatic injector (EPI; 3–6 bar, 50–130 µl; n = 63), and a spring‐loaded jet injector (SLI) with fixed settings (100 µl; n = 9). We measured the immediate skin papule (3D‐camera), residual surface fluid (pipette), dermal dye distribution by estimating depth and width, and subcutaneous dye deposition.

Results

EPI with 4 bar and 100 µl resulted in the largest skin papule of 48.7 mm³ (35.4–62.6 mm³) and widest dermal distribution of 8.0 mm (5.5–9.0 mm) compared to EPI with 6 bar and 100 µl (p < 0.001, p = 0.018, respectively). The skin papule volume showed a significant moderate to high positive correlation with the width and depth of dye distribution in the dermis (r_s = 0.63, r_s = 0.58, respectively; p < 0.001 for both correlations). SLI showed high variability for all outcome measures. Finally, a trend was observed that a small skin papule (≤7 mm) and little residual surface fluid (≤10% of injection volume) were warning signs for subcutaneous deposition.

Conclusions

The immediate skin papule and residual surface fluid correspond with dermal drug deposition and are relevant clinical endpoints for needle‐free jet injector treatments in dermatological practice.

Potent Intradermal Gene Expression of Naked Plasmid DNA in Pig Skin Following Pyro-drive Jet Injection

Intradermal administration of naked DNA with a conventional needle syringe is a simple and inexpensive method to expose an encoded antigen to the dermal immune system. We aimed to enhance intradermal gene expression with a pyro-drive jet injector using pig skin, which is similar in structure and biomechanical properties to human skin. When Cy3-labeled plasmid (pCy3) was applied to pig skin with the jet injector, pCy3 was distributed preferentially in the intradermal tissue. Precise localization analysis revealed that pCy3 was also detected in the intracellular nucleus, and the frequency was substantially higher with the jet injector than with a needle syringe. When a luciferase expression plasmid (pLuc) was injected transdermally, the luciferase activity was 380-fold higher with the jet injector than with a needle syringe. Furthermore, immunohistochemistry analysis showed that the epidermis was positive for luciferase protein expression. These data indicate that the jet injector facilitates stable intradermal administration, resulting in more efficient gene expression compared to that with conventional syringe methods. Thus, intradermal administration of an antigen-expression plasmid with the pyro-drive jet injector may provide a clinically viable method for future gene therapy.

Blood Collection from The Porcine Ear Using a Jet Injector. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2020;2020:5119-5123. [PMID: 33019138 DOI: 10.1109/embc44109.2020.9175421]

We present a new lancet-free method of capillary blood collection for the measurement of blood glucose concentration using a needle-free jet injector. This technique is tested on living animals and directly compared to the current best practice, lancet prick. Shallow jet injection into porcine outer-ear was performed using a portable needle-free jet injector with a slot-shaped nozzle. The jet injections presented used about 25 µL of injectate to penetrate porcine skin to about 1.4 mm, which is within the WHO standards for capillary blood sampling. The blood and fluid released by the jet injections and lancet pricks was collected. The volume and colour of these samples were analysed. The results demonstrate that jet injection is a feasible technique for the collection of capillary blood, despite the small volume of blood samples retrieved from all four pigs. Jet injection may be used in the future to retrieve capillary blood samples from human fingertips.