Microsponges: Development, Characterization, and Key Physicochemical Properties

Microsponges are promising drug delivery carriers with versatile characteristics and controlled release properties for the delivery of a wide range of drugs. The microsponges will provide an optimized therapeutic effect, when delivered at the site of action without rupturing, then releasing the cargo at the predetermined time and area. The ability of the microsponges to effectively deliver the drug in a controlled manner depends on the material composition. This comprehensive review entails knowledge on the design parameters of an optimized microsponge drug delivery system and the controlled release properties of microsponges that reduces the side effects of drugs. Furthermore, the review delves into the fabrication techniques of microsponges, the mechanism of drug release from the microsponges, and the regulatory requirements of the U.S. Food and Drug Administration (FDA) for the successful marketing of microsponge formulation. The review also examines the patented formulations of microsponges. The prospects of these sophisticated drug delivery systems for improved clinical outcomes are highlighted.

Design and Characterization of Dexamethasone Loaded Microsponges for the Management of Ulcerative Colitis

Ulcerative colitis is an inflammatory condition with ulcerations throughout the colon. The existing remedies have some limitations such as drug inactivation, poor absorption, and adverse reactions. The present study aimed to design novel microsponge formulations to enhance remission of the dexamethasone (as a model pharmaceutical ingredient) in the colon. Microsponges were prepared by using the quasi-emulsion technique. The optimal formulation was selected by applying the design of experiments approach which used methylcellulose (MC) (0.75-2%, w/w), polyvinylalcohol (PVA)(0.5-1%, w/w), and tween 80 (TW80) (1.5-2.5%, w/w). The critical quality attributes were selected as particle size and entrapment efficiency. The particle size and encapsulation efficiency were found as 140.38 ± 9.2 µm and 77.96 ± 3.4 %. After the optimization; morphological, thermal, and physicochemical characterization studies were performed. Ultimately, the optimal formulation was investigated by using the acetic acid-induced ulcerative colitis model in rats. The physicochemical characterization studies confirmed that the formulation components were compatible with each other. The in vitro release mechanisms were fitted to First order kinetics at pH 1.2 (R²:0.9563), and Korsmeyer-Peppas kinetics at pH 4.5 (R²: 0.9877), and pH 6.8 (R²: 0.9706). The medicated microsponges exhibited remarkable recovery compared to the control group of the in vivo ulcerative colitis model (p<0.05). It could be concluded that microsponges were evaluated as a promising alternative drug delivery system for the management of ulcerative colitis.

Resveratrol-Loaded Microsponge Gel for Wound Healing: In Vitro and In Vivo Characterization

Objectives

The study was aimed to formulate resveratrol (RSV) loaded microsponges to deliver drug at the wound site and incorporate it in the Moringa oleifera Lam. (Moringaceae) gel base to provide an appropriate moist environment for wound management. RSV, a stilbenoid that activates sirtuins and cell-signaling regulators involved in the process of wound healing.

Materials and Methods

Microsponges were prepared by oil in oil emulsion solvent diffusion method by optimizing the independent variables; drug: polymer ratio and volume of internal phase solvent and their effects on entrapment efficiency and particle size. Formulation batches were evaluated for drug content, production yield, entrapment efficiency, and in vitro drug release. The microsponges were further incorporated into M. oleifera gum gel, which was then evaluated for spreadability, viscosity, ex vivo diffusion study and in vivo studies using an excision wound model in rats.

Results

Scanning electron microscopy revealed spherical and porous nature of the microsponges in vitro-release study of the optimized batch of RSV microsponges showed 80.88% drug release within 8 h. Differential scanning calorimetry results revealed no drug and polymer interaction during the formation of microsponges. An ex vivo diffusion study through goat skin revealed sustained release of RSV through porous microsponges embedded in the gel base at the wound site. An in vivo study performed using an excision wound model showed wound healing and closure within day 8. Histopathology showed increased re-epithelization and reduced ulceration in RSV microsponge gel-treated group compared with sham operated.

Conclusion

RSV microsponge gel delivered the drug at the wound site and the gel base provided a moist environment and influenced cell adhesion, thereby promoting faster wound healing.

Development and Characterization of Polymeric Microsponge as a New Vehicle to Deliver Urea Topically

BACKGROUND

Topical delivery of therapeutic agents is considered beneficial due to various advantages like ease of administration, avoidance of the first-pass effect, and improved patient compliance. Therefore, scientists around the globe are exploring this route for the delivery of drugs nowadays.

OBJECTIVE

The present patent investigation aimed to prepare, optimize, and characterize the urealoaded microsponges for efficient topical delivery in vitro.

METHODS

Urea-loaded ethylcellulose microsponges were prepared using quasi emulsion solvent diffusion technique and optimized using Box-Behnken design (BBD). Furthermore, they were characterized in-vitro using various techniques like scanning electron microscopy (SEM), differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FT-IR), and X-ray diffraction analysis (XRD). In-vitro drug release and release kinetics analysis was also performed.

RESULTS

Urea-loaded microsponges were spherical and porous. Optimized urea loaded microsponges showed a minimum size (39.78 ± 1.98 μm), high entrapment (74.56 ± 2.8%), acceptable polydispersity index (PDI) (0.224 ± 0.081) and zeta potential (-21.9 ± 2.9 mV). These microsponges were capable of sustaining the release of urea for 24 h (91.21 ± 5.20%), and the mechanism of release was the combination of diffusion and erosion.

CONCLUSION

The developed microsponge system could be beneficial for topical delivery of urea as it could reduce the dosing frequency of urea and increase patient compliance through its sustained release.

High-Throughput Production of Microsponges from Platelet Lysate for Tissue Engineering Applications

Cell-based therapies require a large number of cells, as well as appropriate methods to deliver the cells to damaged tissue. Microcarriers provide an optimal platform for large-scale cell culture while also improving cell retention during cell delivery. However, this technology still presents significant challenges due to low-throughput fabrication methods and an inability of the microcarriers to recreate the properties of human tissue. This work proposes, for the first time, the use of methacryloyl platelet lysates (PLMA), a photocrosslinkable material derived from human platelet lysates, to produce porous microcarriers. Initially, high quantities of PLMA/alginate core-shell microcapsules are produced using coaxial electrospray. Subsequently, the microcapsules are collected, irradiated with ultraviolet light, washed, and freeze dried yielding PLMA microsponges. These microsponges are able to support the adhesion and proliferation of human adipose-derived stem cells, while also displaying potential in the assembly of autologous microtissues. Cell-laden microsponges were shown to self-organize into aggregates, suggesting possible applications in bottom-up tissue engineering applications. Impact Statement Microcarriers have increasingly been used as delivery platforms in cell therapy. Herein, the encapsulation of human-derived proteins in alginate microcapsules is proposed as a method to produce microcarriers from photopolymerizable materials. The capsules function as a template structure, which is then processed into spherical microparticles, which can be used in cell culture, cell delivery, and bottom-up assembly. As a proof of concept, this method was combined with lyophilization to process methacryloyl platelet lysates into injectable microsponges for cell delivery.

Development of Thymol Microsponges Loaded in situ Gel for the Treatment of Periodontitis

OBJECTIVE

Periodontitis is an oral disease categorized by disturbance of periodontal tissue and the creation of periodontal pockets. Thymol (TH) loaded microsponge in situ gelling systems was formulated for local action in the periodontal cavity for the management of periodontitis.

METHODS

Solvent evaporation technique was utilized for the preparation of microsponges. A Fractional Factorial Design (FFD) was used to screen the high risk variables impacting the characteristics of the (TH) microsponges and further optimized using Box-Behnken design. The optimized microsponges were then characterized by DSC, SEM, antimicrobial activity, in-vitro release, and then incorporated in the in situ gelling system. A ligature model was used to induce periodontitis in Sprague Dawley rats.

RESULTS

The microsponges showed good characteristics, such as particle size, entrapment efficiency, and mucoadhesiveness of 45 μm, 92.99 ± 0.2%, 96 ± 0.26%, respectively. SEM revealed the spherical morphology of the microsponges with sustained release of TH for 10h and antimicrobial activity against S. mutans and C. albicans. Treatment with Thymol Loaded in situ Gel (THLMG) showed a decrease in gingival inflammation and tooth mobility as well as in serum biochemical parameters like serum Creactive proteins, leucocyte count, alkaline phosphatase, and tartrate-resistant acid phosphatase, when compared to disease group. The histopathological study of the periodontium confirmed a significant reduction of inflammation and alveolar bone destruction (p<0.05) in rats.

CONCLUSION

THLMG decreased the infiltration of inflammatory cells and prevented osteoclastogenesis and osteoblast apoptosis, which further favored a decrease in inflammation and alveolar bone loss in periodontitis. Thus, THLMG could be a better alternative to synthetic antimicrobials and antibiotics to treat periodontitis.

Anti-acne Treatment using Nanotechnology based on Novel Drug Delivery System and Patents on Acne Formulations: A Review

BACKGROUND

Acne is one of the most infectious diseases related to human skin. This disease of acne is of higher prevalence in adults. The main causative organism involved in the acne vulgaris is Propionibacterium acne, which leads to sebum production and follicular hyperkeratinization.

METHODS

The scientific data shows inflammatory mediators of genetic factors, stress, physiological factor, androgens and hormonal changes; all these factors play a major part in the pathophysiology of acne. Several drugs are currently available for the treatment of Acne like bactericidal, antibiotic and several others which are directly or indirectly involved in the eradication of acne.

RESULTS

Nanocarrier systems including liposomes, niosomes, microsponges, nano-emulsion and micro-emulsion, microspheres and solid lipid nanoparticles have emerged as a successful treatment for acne. In this article, the authors have laid special emphasis on these nanocarriers and the study of various patents based on novel technologies in this field. The entrapment of the anti-acne drug molecule into a particular nanocarrier system has been shown to enhance patient compliance and reduction in side-effects.

CONCLUSION

The present review article provides an overview of the mechanism, advantages, drawbacks and various patents associated with the nanocarrier systems involved in acne treatment. Some state of the art patented and novel technologies such as stem cell secretion technology, sol-gel technology incorporating microcapsules and ultrasound delivery of nanoparticles for acne treatment, are also briefly discussed. The patent study on these nanocarriers was done through the worldwide database of the United States patent office, European patent office and several other official patent information websites.

A Review About the Drug Delivery from Microsponges

Microparticulate drug delivery systems have shown a great interest in the pharmaceutical area. They allow the increase of drug therapeutic efficacy and the reduction of side effects. In this context, microsponges represent a new model of porous polymer microspheres, which allow the entrapment of a wide range of active agents. During the development, it is necessary the characterization of the system and among of the most important tests are the release and permeation profile analysis. They can demonstrate the behavior of drug in a specific site with a particular application condition and are related to therapeutic efficacy. Therefore, this review provides an overview of drug delivery profile from microsponges. Methods for determination of in vitro release and ex vivo permeation studies are detailed. Examples of drug delivery from microsponges administered in different sites are also discussed with aim to provide an understanding of the use of this strategy to modify the drug delivery.

Nebivolol-Loaded Microsponge Gel for Healing of Diabetic Wound

An attempt was made to formulate nebivolol-loaded microsponge gel to access drug at wound area, incorporated into gel that possess optimum moist wound management environment during later stages of wound closure. Nebivolol, antihypertensive drug, exhibits vasodilating effects via nitric oxide pathway, slows diabetic neuropathy, and restores endothelial function in diabetic wounds. Microsponges were prepared by optimizing independent variables; drug to polymer ratio and internal phase volume and their effects on production yield, entrapment efficiency, and particle size. Formulations of microsponges were evaluated for drug content. Differential scanning calorimetry indicated reduction in crystallinity of NB during the formation of microsponges. In vitro study (drug to polymer 1:4 and 10 ml internal phase volume acetone) showed 80% drug released within 8 h. Spherical and porous microsponges confirmed by scanning electron microscopy were incorporated in the carbopol 934 (2%) gel base. Gel was characterized for pH, viscosity, and drug content. Less spreadability determined by texture analyzer demonstrated viscous nature of gel. In vitro diffusion study revealed entrapped drug in porous microsponges with slow release to heal wound. In vivo study performed using streptozotocin-induced diabetic rats and excision wound model showed wound healing and closure activity within day 10. Histology revealed inflammatory cell infiltrations and neovascularization in granulation tissues, ultimately healing wound. Microsponge gel prolonged drug release due to entrapped form in porous structure of microsponges with significant and fast wound healing and closure in diabetic rats. Microsponges with loaded drug fulfilled accessibility at wound area, while gel provided optimum moist wound management environment during later stages of wound closure.

Bioadhesive floating microsponges of cinnarizine as novel gastroretentive delivery: Capmul GMO bioadhesive coating versus acconon MC 8-2 EP/NF with intrinsic bioadhesive property

Introduction:

The study was aimed at the development of low-density gastroretentive bioadhesive microsponges of cinnarizine by two-pronged approach (i) coating with bioadhesive material and (ii) exploration of acconon MC 8-2 EP/NF as bioadhesive raw material for fabrication.

Materials and Methods:

Microsponges were prepared by quasi-emulsion solvent diffusion method using 3² factorial design. Capmul GMO was employed for bioadhesive coating. In parallel, potential of acconon for the fabrication of bioadhesive floating microsponges (A8) was assessed.

Results:

Formulation with entrapment efficiency = 82.4 ± 3.4%, buoyancy = 82.3 ± 2.5%, and correlation of drug release (CDR_8h) = 88.7% ± 2.9% was selected as optimized formulation (F8) and subjected to bioadhesive coating (BF8). The %CDR_8h for A8 was similar to BF8 (87.2% ± 3.5%). Dynamic in vitro bioadhesion test revealed comparable bioadhesivity with BF8. The ex vivo permeation across gastric mucin displayed 63.16% for BF8 against 56.74% from A8; affirmed the bioadhesivity of both approaches.

Conclusion:

The study concluded with the development of novel bioadhesive floating microsponges of cinnarizine employing capmul GMO as bioadhesive coating material and confirmed the viability of acconon MC 8-2EP/NF as bioadhesive raw material for sustained targeted delivery of drug.

Fabrication, characterization, and evaluation of microsponge delivery system for facilitated fungal therapy

OBJECTIVE

The rationale behind present research vocation was to develop and investigate a novel microsponge based gel as a topical carrier for the prolonged release and cutaneous drug deposition of fluconazole (FLZ); destined for facilitated fungal therapy.

MATERIALS AND METHODS

Microsponges were prepared using quasi-emulsion solvent diffusion method using Eudragit S-100. In the direction of optimization, the effect of formulation variables (drug-polymer ratio and amount of emulsifier) and diverse factors affecting physical characteristics of microsponge were investigated as well. Fabricated microsponges were characterized by differential scanning calorimetry, Fourier transform-infrared, scanning electron microscopy (SEM), particle size analysis, and also evaluated for drug content, encapsulation efficiency, in vitro drug release and in vitro antifungal activity.

RESULTS

Compatibility studies results reflected no sign of any chemical interaction between the drug and polymers used. Whereas, varied drug-polymer ratios and emulsifier concentration indicated significant effect on production yield, drug content, encapsulation efficiency, particle size and drug release. Spherical microsponges with a porous surface and 29.327 ± 0.31 μm mean particle size were evident from SEM micrographs. In vitro release outcomes, from microsponge loaded gels depicted that F1 formulation was more efficient to give extended drug release of 85.38% at the end of 8 h, while conventional formulation by releasing 83.17% of drug got exhausted incredibly earlier at the end of 4 h merely. Moreover, microsponge gels demonstrated substantial spreadability and extrudability along with promising antifungal activity.

CONCLUSIONS

Fabricated microsponges would be impending pharmaceutical topical carriers of FLZ and a leading alternative to conventional therapy for efficient, safe and facilitated eradication of fungal infections.

Factorial designed 5-fluorouracil-loaded microsponges and calcium pectinate beads plugged in hydroxypropyl methylcellulose capsules for colorectal cancer

INTRODUCTION

The work was aimed to develop an enteric-coated hydroxypropyl methylcellulose (HPMC) capsules (ECHC) plugged with 5-fluorouracil (5-FU)-loaded microsponges in combination with calcium pectinate beads.

MATERIALS AND METHODS

The modified quasi-emulsion solvent diffusion method was used to prepare microsponges. A 3(2) factorial design was employed to study the formulation and the effects of independent variables (volume of organic solvent and Eudragit-RS100 content) on dependent variables (particle size, %entrapment efficiency, and %cumulative drug release). The optimized microsponge (F4) was characterized by scanning electron microscopy, powder X-ray diffraction, and thermogravimetric analysis. F4 was plugged along with the calcium pectinate beads in HPMC capsules coated with enteric polymer Eudragit-L100 (Ed-L100) and/or Eudragit-S100 (Ed-S100) in different proportions. An in vitro release study of ECHC was performed in simulated gastric fluid for 2 h, followed by simulated intestinal fluid for next 6 h and then in simulated colonic fluid (in the presence and absence of pectinase enzyme for further 16 h). The optimized formulation was subjected to in vivo roentgenographic and pharmacokinetic studies in New Zealand white rabbits to analyze the in vivo behavior of the developed colon-targeted capsules.

RESULTS

Drug release was retarded on coating with Ed-S100 in comparison to a blend of Ed-S100:Ed-L100 coating. The percentage of 5-FU released at the end of 24 h from ECHC3 was 97.83 ± 0.12% in the presence of pectinase whereas in the control study, it was 40.08 ± 0.02%.

CONCLUSION

Thus, enteric-coated HPMC capsules plugged with 5-FU-loaded microsponges and calcium pectinate beads proved to be a promising dosage form for colon targeting.

RNAi-microsponges form through self-assembly of the organic and inorganic products of transcription

Inorganic nanostructures have been used extensively to package nucleic acids into forms useful for therapeutic applications. Here we report that the two products of transcription, RNA and inorganic pyrophosphate, can self-assemble to form composite microsponge structures composed of nanocrystalline magnesium pyrophosphate sheets (Mg₂P₂O₇•3.5H₂O) with RNA adsorbed to their surfaces. The microsponge particles contain high loadings of RNA (15-21 wt.%) that are protected from degradation and can be obtained through a rolling circle mechanism as large concatemers capable of mediating RNAi. The morphology of the RNAi microsponges is influenced by the time-course of the transcription reaction and interactions between RNA and the inorganic phase. Previous work demonstrated that polycations can be used to condense RNAi microsponges into nanoparticles capable of efficient transfection with low toxicity. Our new findings suggest that the formation of these nanoparticles is mediated by the gradual dissolution of magnesium pyrophosphate that occurs in the presence of polycations. The simple one-pot approach for assembling RNAi microsponges along with their unique properties could make them useful for RNA-based therapeutics.

Microsponges: A novel strategy for drug delivery system

Microsponges are polymeric delivery systems composed of porous microspheres. They are tiny sponge-like spherical particles with a large porous surface. Moreover, they may enhance stability, reduce side effects and modify drug release favorably. Microsponge technology has many favorable characteristics, which make it a versatile drug delivery vehicle. Microsponge Systems are based on microscopic, polymer-based microspheres that can suspend or entrap a wide variety of substances, and can then be incorporated into a formulated product such as a gel, cream, liquid or powder. The outer surface is typically porous, allowing a sustained flow of substances out of the sphere. Microsponges are porous, polymeric microspheres that are used mostly for topical use and have recently been used for oral administration. Microsponges are designed to deliver a pharmaceutical active ingredient efficiently at the minimum dose and also to enhance stability, reduce side effects, and modify drug release.