Evaluating the effectiveness of a novel atomized liquid needle-free transdermal delivery system

Elongated microparticles tuned for targeting hyaluronic acid delivery to specific skin strata

OBJECTIVE

Microneedle or fractional laser applications are the most common topical delivery enhancement platforms. However, these methods of drug delivery are not skin strata specific. Drug delivery approaches which could target specific stratum of the skin remains a challenge. Elongated microparticles (EMPs) have been used in enhancing drug delivery into the skin. The aim of this study was to evaluate, for the first time, elongated silica microparticles with two different length profiles to enhance delivery of hyaluronic acid into different strata of human skin.

METHODS

Two types of EMPs - long (milled EMPs) or short (etched EMPs) length ranges were characterized. A prototypical liquid formulation (Fluorescent hyaluronic acid) with and without EMP enhancement were evaluated for hyaluronic acid delivery in ex-vivo human skin. High Performance Liquid Chromatography (HPLC), Typhoon fluorescence scanning system, Laser Scanning Confocal Microscopy (LSCM) and Reflectance Confocal Microscopy (RCM) were used to validate F-HA stability, visualize fluorescein in the skin, image the depth of F-HA delivery in the skin and define EMP penetration in skin strata, respectively. Statistical analysis was conducted using GraphPad Prism 6 software (GraphPad Software Inc, USA).

RESULTS

Fluorescein-hyaluronic acid was stable and EMP enhanced skin penetration. Reflectance confocal microscopy revealed that "etched EMP" penetrated the skin to the stratum spinosum level. The vast majority (97.8%; p < 0.001) of the etched EMP did not penetrate completely through the viable epidermis and no obvious penetration into the dermis. In contrast, milled EMP showed 41-fold increase in penetration compared to the etched EMP but penetrated beyond the dermoepidermal junction.

CONCLUSION

EMPs can enhance delivery of hyaluronic acid. Using EMPs with defined length distributions, which can be tuned for a specific stratum of the skin, can achieve targeted hyaluronic acid delivery.

Clinical Evaluation of Sequential Transdermal Delivery of Vitamin B6, Compound Glycyrrhizin, Metronidazole, and Hyaluronic Acid Using Needle-Free Liquid Jet in Facial Seborrheic Dermatitis

Facial seborrheic dermatitis (FSD) is a common facial inflammatory dermatitis. Needle-free transdermal jet injection (NTJI) is a non-invasive injection of drug solution by using a high-pressure liquid injection instrument. To explore a safer, more tolerable, and convenient medical way using NTJI in the treatment of FSD, the patients were treated with vitamin B6, glycyrrhizin compound, metronidazole, and hyaluronic acid sequentially using NTJI every 2 weeks, and only those treated for more than three times were included. A VISIA facial imaging system for the evaluation of erythema, superficial lipid level, and roughness of skin surface and a CK analyzer for biophysical parameters, including the stratum corneum hydration, facial surface lipid, and trans-epidermal water loss, were applied. Erythema was significantly reduced after every treatment (weeks 2, 4, and 6; P < 0.05), whereas superficial lipid level was not improved significantly until week 6 (P < 0.05), and roughness of the skin surface was not improved significantly during the whole treatment. The stratum corneum hydration of lesional skin was significantly increased after three times of treatment (P < 0.05). No observable adverse effect, such as marked erythema, blistering, or atrophy, was observed. Sequential transdermal delivery of small molecular weight drugs (vitamin B6, glycyrrhizin compound, metronidazole, and hyaluronic acid) using NTJI is a safe, low-toxicity, and take-home drug-free therapy for the treatment of FSD.

Transdermal delivery of topical lidocaine in a mouse model is enhanced by treatment with cold atmospheric plasma

BACKGROUND

Topical anesthetics are widely used in dermatology and cosmetology to alleviate the pain from nonsurgical cosmetic procedures, while the transdermal drug delivery is limited by the skin barrier. Cold atmospheric plasma (CAP) is a potential approach used for skin pretreatment to enhance transdermal delivery of topical medications.

AIMS

To assess the efficacy of CAP as a pretreatment to improve the transdermal delivery of topical anesthetic.

METHODS

First, we conducted ex vivo permeation studies on 30 mice with a Franz cell diffusion experiment. CAP irradiations of different intensity and duration were pretreated on the epidermal layer of mice before topical lidocaine applied, with the control group received no pretreatment. The amount of drug penetrated through the skin and drug flux were determined by high-performance liquid chromatography. Then, we treated 3 living mice with CAP followed by application of methylene blue cream (MB) and used skin biopsies to measure penetration depth by microscope. Last, we measured the transepidermal water loss (TEWL) of mouse skin in vivo before and after CAP treatment to observe its effect on the skin barrier function.

RESULTS

In the permeation study, the transdermal flux of lidocaine was enhanced to 1.97 times of the control samples by CAP pretreatment. We also observed that the accumulative amount of lidocaine varied with the duration of the CAP treatment in a biphasic manner. In the MB penetration study, significant amount of MB deposition was observed under the epidermis and deeper parts of the skin after CAP pretreatment compared with the control sample. A sharp increase in TEWL value was observed directly after the CAP treatment, but 30 minutes later, it began to decrease and recovered to baseline in the next 3 hours, indicating that the skin barrier property had been changed reversibly.

CONCLUSIONS

Our studies suggested that the transdermal absorption of topical lidocaine can be efficiently and safely enhanced by pretreatment of the skin with CAP. We believe that CAP could be used as an assistance to improve analgesia in dermatology.