Physicochemical and Drug Release Characterization of Lidocaine-Loaded Transdermal Patches Prepared from STR-5L Block Rubber

Ionic Liquid-Based Immunization Patch for the Transdermal Delivery of Antigens

Herein, we report a transdermal patch prepared using an ionic liquid-based solid in oil (IL-S/O) nanodispersion and a pressure-sensitive adhesive (PSA) to deliver the macromolecular antigenic protein, ovalbumin (OVA). The IL-S/O nanodispersion and a PSA were first mixed at an equal weight ratio, then coated onto a release liner, and covered with a support film. To evaluate the effect of the PSA, three types of PSAs, DURO-TAK 87-4098, DURO-TAK 87-4287, and DURO-TAK 87-235A, were used to obtain the corresponding IL-S/O patches SP-4098, SP-4287, and SP-235A, respectively. The prepared IL-S/O patches were characterized for surface morphology, viscoelasticity, and moisture content. In vitro skin penetration and in vivo immunization studies of the IL-S/O patches were performed using Yucatan micropig skin and the C57BL/6NJc1 mice model, respectively. The SP-4098 and SP-4287 delivered 5.49-fold and 5.47-fold higher amounts of drug compared with the aqueous formulation. Although both patches delivered a similar amount of drug, SP-4287 was not detached fully from the release liner after 30 days, indicating low stability. Mice immunized with the OVA-containing SP-4098 produced a 10-fold increase in anti-OVA IgG compared with those treated with an aqueous formulation. These findings suggested that the IL-S/O patch may be a good platform for the transdermal delivery of antigen molecules.

Formulation Development and Pharmaceutical Evaluation of Lysiphyllum strychnifolium Topical Patches for Their Anti-inflammatory Potential

Topical drug delivery systems are interesting and popular dosage forms for formulation development. Thai herbs are used in alternative medicine to treat patients suffering from severe illnesses. They have significant economic and cultural value in Thailand. This work prepared Thai herbal topical patches of Lysiphyllum strychnifolium stem extracts using pectin and Eudragit^® NM 30D, and glycerin as a plasticizer. Astilbin was selected as a chemical marker in L. strychnifolium stem extracts. The L. strychnifolium stem extracts showed a statistically significant decrease in nitrate accumulation. The various properties of Thai herbal topical patches were not significantly different from blank patches. However, the trends of the properties depended on the amount of Eudragit^® NM 30D. All ingredients were homogeneously mixed in Thai herbal topical patches and showed a smooth and compact film. The astilbin content was found in a range of 52.72-63.36 μg/cm². The in vitro release of astilbin depended on the amount of Eudragit^® NM 30D. The kinetics of astilbin release were fitted to the Korsmeyer-Peppas model. The astilbin showed low permeation; thus, polyethylene glycol 400 was used as a permeation enhancer. Polyethylene glycol 400 could increase the permeation rates of astilbin and the cumulative amount of astilbin in pig skin. This would be suitable for preparing the Thai herbal topical patches and could be developed for pharmaceutical and herbal products.

Interfacial interaction of anesthetic lidocaine and mesoporous silica nanoparticles in aqueous solutions and its release properties

Lidocaine has been used as a local anesthetic by injection. The controlled release of lidocaine loaded into nanospheres is necessary to reduce the onset time of the anesthetic effect or increase the anesthetic analgesia duration. In this study, mesoporous silica nanoparticles (MSNs) with a large specific surface area were prepared by a sol-gel method, and the interfacial interaction between MSNs and lidocaine positively charged in aqueous solutions at different concentrations was investigated by adsorption tests, Fourier-transformed infrared spectroscopy, thermogravimetry-differential thermal analysis, and Brunauer-Emmett-Teller (BET) measurements. The electrostatic interaction between Si-OH on MSNs and lidocaine-NH⁺ was of importance for the adsorption phenomenon in aqueous solutions, indicating the monolayer adsorption of lidocaine. BET measurements also supported the decrease of pore volumes, and the hysteresis loop of the isotherm curve was not closed since the condensation of lidocaine in the mesopores formed micropores of less than 1.5 nm in size. The release profiles in phosphate buffered saline containing calcium and magnesium ions showed a rapid and higher release of lidocaine compared with that in phosphate buffered saline without divalent cations. The released lidocaine concentrations were sufficient for the expression of the anesthetic effect in dental anesthesia.

Gold Nanoparticle and Hydrophobic Nanodiamond Based Synergistic System: A Way to Overcome Skin Barrier Function

Gold nanoparticles (AuNP) have attracted ample attention as a transdermal (TND) drug delivery platform for improving the skin permeability of drug molecules. Herein a novel TND device formed from AuNP and oleylamine functionalized nanodiamond (AuD) has been developed successfully for the TND delivery of Ketoprofen (KP), a model drug. Poly(vinyl alcohol)/Polybutyl methacrylate (PVA/PBMA) film has been selected as the matrix of the TND device, as they furnish excellent skin adhesion properties. The PVA/PBMA membranes loaded with different concentrations of AuD have been characterized in terms of surface morphology, thermomechanical properties, water vapor permeability (WVP), optical transmittance, cosmetic attractiveness, skin adhesion behavior, and drug encapsulation efficiency (DEE). The matrix loaded with 3.0% AuD displayed enhanced thermomechanical and DEE due to the uniform distribution of nanofillers in the membrane. The in vitro skin permeation test proved that a higher amount of KP was delivered by AuD incorporated films, suggesting improved TND behavior. The synergistic management of AuNP and nanodiamonds (ND) has caused the enhanced skin permeation behavior of the device. The obtained results revealed that AuD may be employed as an effective carrier to substitute NDs for TND delivery. Additionally, while investigating the storage stability of the device we observed that the membrane kept at low temperature presented stability over time. More importantly, the results from cell viability assay and environmental fitness test revealed that the AuD based TND system is a high security device, as it is noncytotoxic and microbe-resistant. The developed device provides a novel and handy approach to the TND delivery of drug molecules.

Methacrylate-Stitched β-Cyclodextrin Embedded with Nanogold/Nanotitania: A Skin Adhesive Device for Enhanced Transdermal Drug Delivery

Transdermal (TD) drug delivery is a more attractive technique for drug delivery compared to oral and intravenous injection. However, the permeation of drug molecules across the skin is difficult due to the presence of highly ordered lipid barrier. This study details the development of a novel TD system, which has the potential to simultaneously enhance the skin permeability and adhesion behavior. Ibuprofen (IP) was selected as model drug. The ability of gold nanoparticle (AuNP) and hydrophobic titanium nanotube (TNT) to enhance the skin permeability was explored. Additionally, β-cyclodextrin (βCD), which can exceptionally encapsulate poorly water-soluble drugs, is grafted with methacrylates to improve the skin adhesion property. Finally, Au-TNT nanocomposite was deposited onto methacrylate-grafted βCD matrix. The developed material was characterized through NMR spectroscopy, infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Raman spectroscopy. The characteristics of the film, including water vapor permeability (WVP), thermomechanical properties, etc., were examined in terms of Au-TNT content. The TD delivery of IP with different concentrations of Au-TNT was evaluated via an in vitro skin permeation study through rat skin. It is revealed that the prepared TD film exhibited an improved drug-delivery performance due to the synergistic action of AuNP and hydrophobic TNT. The cumulative percent of IP delivered across the skin is extremely depending on nanofiller content, lipophilicity, and thickness of the membrane, and the device incorporated with 4.0% Au-TNT displayed the best performance. In addition, a study on storage stability was performed by storing the films for 2 months at different temperatures. The study revealed that the device possessed excellent storage stability when stored at low temperature. The developed film offers excellent WVP, drug encapsulation efficiency, thermomechanical properties, and skin adhesion behavior. Moreover, the device was cosmetically attractive, noncytotoxic, and resistant to microbial growth and hence extremely reliable for skin application. The developed skin permeation strategy may open new avenues in TD drug delivery.