Investigating the influence of ultrasound parameters on ibuprofen drug release from hydrogels

pH-responsive zeolite-A/chitosan nanocarrier for enhanced ibuprofen drug delivery in gastrointestinal systems

Targeted drug delivery with responsive release is an emerging research area. Along this line, we report herein the fabrication and characterization of zeolite/chitosan (ZA/CS) composite as a pH-responsive drug carrier for ibuprofen. The drug loading and release, along with cytotoxicity, have been examined to assessing the effectiveness of ZA/CS composite as an ibuprofen therapeutic delivery system. The ZA/CS composite demonstrates a drug loading content (DLC) of 1989.13 mg/g and an entrapment efficiency content (EEC) of 99.88 %, as determined by drug loading. The released ibuprofen demonstrated virtually linear behavior in fluids that simulated the pH values of the gastrointestinal system. The release at pH 1.2 reached 55 % after 2 h. Seven kinetic models were tested to simulate the drug release process. The Ritger-Peppas model was determined to be the most suitable model. The estimated diffusion exponent (n) values were calculated to be 0.863 at pH 1.2 and 0.981 at pH 7.4, suggesting anomalous or non-Fickian diffusion mechanisms. Importantly, the ZA/CS composite exhibited excellent biocompatibility as demonstrated by a cytotoxicity evaluation using the MTT assay. These unique features render the examined ZA/CS composite a promising candidate for future targeted drug delivery applications.

Mixed Micellar Gel of Poloxamer Mixture for Improved Solubilization of Poorly Water-Soluble Ibuprofen and Use as Thermosensitive In Situ Gel

The aqueous solution of binary mixtures of amphiphilic copolymers is a potential platform for fabricating mixed polymeric micelles for pharmaceutical applications, particularly in developing drug delivery depots for a poorly water-soluble compound. This study fabricated and investigated binary mixtures of poloxamer 403 (P403) and poloxamer 407 (P407) at varying P403:P407 molar ratios to develop a vehicle for the poorly water-soluble compound, using ibuprofen as a model drug. The cooperative formation of mixed micelles was obtained, and the solubility of ibuprofen in the binary mixtures was enhanced compared to the solubility in pure water and an aqueous single P407 solution. The binary mixture with the P403:P407 molar ratio of 0.75:0.25 at a total polymer concentration of 19% w/v exhibited the temperature dependence of micellization and sol-to-gel characteristics of the thermosensitive mixed micellar gels. It possessed suitable micellization and gelation characteristics for in situ gelling systems. The release of ibuprofen from the thermosensitive mixed micellar depots was sustained through a diffusion-controlled mechanism. The findings can aid in formulating binary mixtures of P403 and P407 to achieve the desired properties of mixed micelles and micellar gels.

A, Nayak UY. Low-Frequency Sonophoresis: A Promising Strategy for Enhanced Transdermal Delivery

Sonophoresis is the most approachable mode of transdermal drug delivery system, wherein low-frequency sonophoresis penetrates the drug molecules into the skin. It is an alternative method for an oral system of drug delivery and hypodermal injections. The cavitation effect is thought to be the main mechanism used in sonophoresis. The cavitation process involves forming a gaseous bubble and its rupture, induced in the coupled medium. Other mechanisms used are thermal effects, convectional effects, and mechanical effects. It mainly applies to transporting hydrophilic drugs, macromolecules, gene delivery, and vaccine delivery. It is also used in carrier-mediated delivery in the form of micelles, liposomes, and dendrimers. Some synergistic effects of sonophoresis, along with some permeation enhancers, such as chemical enhancers, iontophoresis, electroporation, and microneedles, increased the effectiveness of drug penetration. Sonophoresis-mediated ocular drug delivery, nail drug delivery, gene delivery to the brain, sports medicine, and sonothrombolysis are also widely used. In conclusion, while sonophoresis offers promising applications in diverse fields, further research is essential to comprehensively elucidate the biophysical mechanisms governing ultrasound-tissue interactions. Addressing these gaps in understanding will enable the refinement and optimization of sonophoresis-based therapeutic strategies for enhanced clinical efficacy.

Translating ultrasound-mediated drug delivery technologies for CNS applications

Ultrasound enhances drug delivery into the central nervous system (CNS) by opening barriers between the blood and CNS and by triggering release of drugs from carriers. A key challenge in translating setups from in vitro to in vivo settings is achieving equivalent acoustic energy delivery. Multiple devices have now been demonstrated to focus ultrasound to the brain, with concepts emerging to also target the spinal cord. Clinical trials to date have used ultrasound to facilitate the opening of the blood-brain barrier. While most have focused on feasibility and safety considerations, therapeutic benefits are beginning to emerge. To advance translation of these technologies for CNS applications, researchers should standardise exposure protocol and fine-tune ultrasound parameters. Computational modelling should be increasingly used as a core component to develop both in vitro and in vivo setups for delivering accurate and reproducible ultrasound to the CNS. This field holds promise for transformative advancements in the management and pharmacological treatment of complex and challenging CNS disorders.

Encapsulation of the growth factor neurotrophin-3 in heparinised poloxamer hydrogel stabilises bioactivity and provides sustained release

Poloxamer-based hydrogels show promise to stabilise and sustain the delivery of growth factors in tissue engineering applications, such as following spinal cord injury. Typically, growth factors such as neurotrophin-3 (NT-3) degrade rapidly in solution. Similarly, poloxamer hydrogels also degrade readily and are, therefore, only capable of sustaining the release of a payload over a small number of days. In this study, we focused on optimising a hydrogel formulation, incorporating both poloxamer 188 and 407, for the sustained delivery of bioactive NT-3. Hyaluronic acid blended into the hydrogels significantly reduced the degradation of the gel. We identified an optimal hydrogel composition consisting of 20 % w/w poloxamer 407, 5 % w/w poloxamer 188, 0.6 % w/w NaCl, and 1.5 % w/w hyaluronic acid. Heparin was chemically bound to the poloxamer chains to enhance interactions between the hydrogel and the growth factor. The unmodified and heparin-modified hydrogels exhibited sustained release of NT-3 for 28 days while preserving the bioactivity of NT-3. Moreover, these hydrogels demonstrated excellent cytocompatibility and had properties suitable for injection into the intrathecal space, underscoring their suitability as a growth factor delivery system. The findings presented here contribute valuable insights to the development of effective delivery strategies for therapeutic growth factors for tissue engineering approaches, including the treatment of spinal cord injury.

Enhanced transscleral delivery using superficial ultrasound exposure and drug-loaded hydrogel

This study employed superficial ultrasound exposure of good ocular safety and a drug-loaded hydrogel of long residence time to enable transscleral delivery. First, we designed an acoustic adaptor to limit the ultrasound exposure depth to 1.59 mm to protect the posterior eye segments. Then, we optimized the alginate/polyacrylamide ratio (3:7) of a dual-crosslinked hydrogel to enable ultrasound-triggered release of model drug (70-kDa fluorescein isothiocyanate-conjugated dextran). Using fluorescence imaging to quantify the drug release, we showed that the developed method resulted in enhanced transscleral delivery in both ex vivo porcine scleras (2.6-fold) and in vivo rabbit scleras (2.2-fold). We also demonstrated that the method increased the drug penetration depth to the whole thickness of the sclera. In particular, the drug release efficiency increased with increasing ultrasound exposure time (1 and 3 min) and intensity (8, 19, 36, and 61 mW/cm2). Using scanning electron microscopy, we revealed that ultrasound exposure resulted in rougher surfaces and microscale rupture of the hydrogel. Moreover, Masson staining of scleral slices showed that the integrity of the top scleral fibers was disturbed by ultrasound exposure, and this disturbance recovered 3 days later. Our work demonstrates that the developed method holds great potential for mediating ocular drug delivery.