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Microneedles and Transdermal Transport
Published in Boris Stoeber, Raja K Sivamani, Howard I. Maibach, Microneedling in Clinical Practice, 2020
Physical Enhancers:8Iontophoresis: Iontophoresis involves the use of a small electrical current, either directly or indirectly, to aid in the movement of charged particles across the skin.Electroporation: Electroporation, unlike iontophoresis, uses high-voltage pulses to create small pathways within the skin's lipid bilayer, resulting in increased skin permeability.11Sonophoresis: Like electroporation, high-frequency sonophoresis also forms small holes in the skin to increase drug permeability. However, sonophoresis relies on ultrasound waves. It has been used to deliver topical steroids and NSAIDs.12Microneedles: Microneedles form small holes in the stratum corneum, allowing for drug penetration through the least permeable layer of the skin. This method will be discussed in further detail below.
Innovations and Future Prospects of Dermal Delivery Systems
Published in Tapash K. Ghosh, Dermal Drug Delivery, 2020
Rashmi Upasani, Anushree Herwadkar, Neha Singh, Ajay K. Banga
Sonophoresis utilizes ultrasonic energy to deliver drugs into or through the skin. While research studies with high frequency ultrasound (> 0.7MHz) have been documented since the 1950s, low frequency sonophoresis (20–100KHz) is a relatively newer field that has been investigated in the last two decades. These two technologies differ in the mechanism and extent of permeability enhancement and have varied applications.
Topical Photodynamic Therapy for Skin Diseases: Current Status of Preclinical and Clinical Research, Nanocarriers and Physical Methods for Photosensitizer Delivery
Published in Andreia Ascenso, Sandra Simões, Helena Ribeiro, Carrier-Mediated Dermal Delivery, 2017
Fabíola Silva Garcia Praça, Patricia Mazureki Campos, Josimar O. Eloy, Raquel Petrilli, Maria Vitória Lopes Badra Bentley, Wanessa Silva Garcia Medina
Sonophoresis is the use of ultrasound for drug delivery. High (>0.7 MHz) or low (20-100 kHz) frequencies of ultrasound are able to increase the drug transportation through the skin by cavitation effects. Noteworthy, low frequencies of ultrasound are more effective in enhancing skin permeability of drugs; however, both techniques can improve local, regional and systemic drug delivery [178]. For example, low frequency of ultrasound can be applied before or simultaneously to drug delivery, enhancing drug molecules permeation by structural alterations or induced convection flow across the skin. 5-ALA had its permeation enhanced across human skin ex vivo, using low frequency sonophoresis before the 5-ALA diffusion assay. The results indicated that sonophoresis exerted a significant accumulation of 5-ALA into full thickness skin compared to passive permeation during 8 h of permeation, also, the same occurred for 5-ALA skin retention, which overcomes the hydrophilicity of 5-ALA, contributing to tumor delivery and increase of 5-ALA clinical response [179].
Microneedle arrays for vaccine delivery: the possibilities, challenges and use of nanoparticles as a combinatorial approach for enhanced vaccine immunogenicity
Published in Expert Opinion on Drug Delivery, 2018
Aoife Maria Rodgers, Ana Sara Cordeiro, Adrien Kissenpfennig, Ryan F Donnelly
The SC barrier of the skin makes it difficult for antigenic compounds (usually biomolecules with a high molecular weight > 500 Da) to penetrate to the epidermis and dermis, in which the immune cells are located. Numerous studies have demonstrated that topical application of antigen formulations is insufficient to yield adequate immune responses. As such, physical and chemical techniques to disrupt the SC barrier have been proposed to enhance antigen delivery through the epidermis for targeting of APCs. The most common physical techniques include tape-stripping, gene guns, iontophoresis, sonophoresis, electroporation and MN [2,54–56], while chemical permeation enhancers such as alcohols, sulphoxides, essential oils, fatty acids and urea, among others, have also been studied in this field [57,58]. While iontophoresis has the advantage of acting more on the drug than on the skin, and consequently has a lower risk of damaging the skin structure, its use is limited to charged low molecular weight molecules. In the case of sonophoresis, despite being quite flexible and adjustable to specific needs, the process itself is complicated and carries a risk of skin burning by the ultrasound waves [2,58]. Given the versatility of the MN approach and the larger amount of published studies focussing on the use of this platform for transdermal vaccination, in this review we focus specifically on the use of MN to facilitate vaccine delivery.
Combined effect of sonophoresis and a microemulsion on the dermal delivery of celecoxib
Published in Drug Delivery, 2020
Sonophoresis is a physical technique that applies low-frequency ultrasound (18-100 kHz) to increase skin penetration (Herwadkar et al., 2012). Many reports have shown that sonophoresis can increase the skin penetration of many drugs, such as ketoprofen (Herwadkar et al., 2012), heparin (Mitragotri & Kost, 2001), niacinamide (Park et al., 2019), and minoxidil (Park et al., 2019). Although sonophoresis could enhance skin penetration, the corresponding mechanisms have still not been evaluated. It has been proposed that the enhancement mainly results from cavitation effects (Azagury et al., 2014; Park et al., 2014). It has also been suggested that the stratum corneum barrier is weakened by small bubbles generated from sonophoresis.
Microneedle Systems for Vaccine Delivery: the story so far
Published in Expert Review of Vaccines, 2020
Md Kamal Hossain, Taksim Ahmed, Prabhat Bhusal, Robhash Kusam Subedi, Iman Salahshoori, M Soltani, Majid Hassanzadeganroudsari
The SC layer of the skin provides strong resistance and makes it difficult for antigens of high molecular weight to penetrate to the epidermis and dermis, in which the APCs are located. The topical application of vaccines failed in most cases to produce efficient antibody response. Some common physical methods such as iontophoresis, laser-assisted vaccine delivery, tape-stripping, sonophoresis, gene guns, electroporation, and MNs [47–50] and chemical methods using various penetration enhancers, such as surfactants and other chemicals, have been proposed to increase the antigen delivery into the dermis and epidermis to target APCs [33,51]. Iontophoresis was found to be safe, but its usages are limited to charged molecules with low molecular weight. The sonophoresis technique is flexible and can be customized for specific purposes but the process is complicated and associated with skin damage and burns [33,47]. Laser-mediated vaccine delivery was found to be promising. Skin pre-treated by laser therapy can improve the vaccine delivery through skin. Laser pre-treatment can also prime the body’s immune system to best respond to the vaccine and thus work as an adjuvant [52–54]. However, it may burn the skin and change skin pigmentation. This platform is still in its early stages and more clinical studies are required to validate its effectiveness to deliver vaccines to humans [55]. Among all the techniques evaluated, MN patches are one of the most successful techniques to deliver the vaccine to the APCs rich region of the skin that is into the dermis and epidermis. They have been investigated extensively and have generated a substantial body of information to support the application of MNs for intradermal vaccination.