Microparticulate Systems Research Articles

Isoniazid-gelatin conjugate microparticles containing rifampicin for the treatment of tuberculosis

In this work, a new polymeric microparticle system based on gelatin covalently bound to isoniazid (ISN) and containing rifampicin (RFP) was prepared by spray-drying technique. Microparticle aptitude to nebulisation and their capability of interacting with A549, alveolar basal epithelial cells, were evaluated in vitro. Microparticles were obtained by spray drying, and their morphology, size, zeta potential, thermotropic behaviour and nebulisation ability were evaluated. Microparticles were positively charged with a mean size of 4.88 ± 0.3 μm. Microspheres were able to incorporate both RFP and ISN: encapsulation efficiency was 51 ± 6% and 22 ± 1%, respectively. X-ray diffraction study showed a new extensive and flattened diffraction peak providing evidence that the drugs were dispersed into the microparticles. Differential scanning calorimetry analysis confirmed effective interactions between gelatin and drug molecules by the presence of new transition peaks. Fifty-nine per cent of used microparticles were aerosolised. In-vitro toxicity studies on A549 alveolar basal epithelial cells showed that microparticles decreased cytotoxicity in comparison with the RFP solution. Laser scanning confocal microscopy observation confirmed that fluorescent probes delivered by microparticles are efficiently internalised in A549 cells. Overall, microparticles based on gelatin covalently bound to ISN and containing RFP showed a promising behaviour for pulmonary drug delivery.

Testosterone implants modify the steroid hormone balance and the gonadal physiology of gilthead seabream (Sparus aurata L.) males

Androgens can induce complete spermatogenesis in immature or prepubertal teleost fish; however, many aspects of the role of androgens in adult teleost spermatogenesis remain elusive. We used the in situ forming microparticle (ISM) system containing 1mg of testosterone (T)/kg body weight (T-ISM) in a homogenous population of gilthead seabream at testicular involution stage to study in vivo the effects of T on the sex steroid hormone balance and on the physiology of the gilthead seabream gonad. The levels of T, 11-ketotestosterone (11KT) and 17β-estradiol (E2) in plasma, gonad and liver were determined in T-ISM implanted specimens after 7, 14, 21 and 28 days. The effect of T-ISM was evaluated on (i) de novo synthesis and metabolism of T in the gonad and liver by measuring the gene expression levels of the main steroidogenic proteins involved, (ii) the progress of spermatogenesis, (iii) the presence of different leukocyte cell types in the gonad, and (iv) the mRNA expression of some genes involved in the leukocyte migratory influx into the gonad and of some immune-relevant molecules. T-ISM implants promote an increase of T up to supra-physiological levels which induce a depletion of E2 levels and maintain the 11KT levels at physiological concentrations. The gene expression profile of some steroidogenic enzymes in gonad and liver ruled out the transformation of T into estrogenic compounds following T-ISM implantation. Moreover, androgens may also be involved in the leukocyte migratory influx, which occurred even when cytokine, chemokine and cell adhesion molecule gene expressions were down-regulated. Moreover, T-ISM implants block germ cell proliferation, although increased dmrt1 gene expression may prevent the complete depletion of germ cells in the gonad. Furthermore, T down-regulated the expression of several tlr genes, which may result in the inhibition of the immune response in the gonad through the impaired ability to recognize and respond to pathogens.

Magnetic Porous Sugar-Functionalized PEG Microgels for Efficient Isolation and Removal of Bacteria from Solution

Here, we present a new microparticle system for the selective detection and magnetic removal of bacteria from contaminated solutions. The novelty of this system lies in the combination of a biocompatible scaffold reducing unspecific interactions with high capacity for bacteria binding. We apply highly porous poly(ethylene glycol) (PEG) microparticles and functionalize them, introducing both sugar ligands for specific bacteria targeting and cationic moieties for electrostatic loading of superparamagnetic iron oxide nanoparticles. The resulting magnetic, porous, sugar-functionalized (MaPoS) PEG microgels are able to selectively bind and discriminate between different strains of bacteria Escherichia coli . Furthermore, they allow for a highly efficient removal of bacteria from solution as their increased surface area can bind three times more bacteria than nonporous particles. All in all, MaPoS particles represent a novel generation of magnetic beads introducing for the first time a porous, biocompatible and easy to functionalize scaffold and show great potential for various biotechnological applications.

Abstract 4340: Formulation of oral microparticulate drug delivery system for cancer.

Abstract The development of oral controlled-release cancer drug formulations with enhanced bioavailability and efficacy is highly desired. Our research aim to develop controlled-release capsule formulations containing sulforaphane-encapsulated in a biodegradable polymeric microparticulate system. Sulforaphane, a histone deacetylase inhibitor (HDAC), was investigated as this therapeutic agent reverses aberrant epigenetic changes in cancer cells and the effects of this drug are reversible. Biodegradable polymeric microspheres were prepared by a microencapsulation method, and prepared microspheres were characterized for various properties, including encapsulation efficiency, percent yield, particle size, size distribution, surface morphology, and Zeta potential. Dissolution studies were carried out to analyze the release profiles of the microspheres and capsule-containing microsphere formulations. Data indicated that microspheres were less than 2-μm in diameter size. It has been shown that particles within this size range are effectively taken in by the cells. The prepared microsphere formulations had Zeta potential values of about -30 mV, which suggest that they are stable. Furthermore, microsphere formulations were shown to provide controlled-release of the drug over 36 hours. Capsule formulations containing microspheres exhibited similar drug release characteristics; however, the lag time for drug release was longer. Thus, oral gelatin capsules containing sulforaphane-encapsulated biodegradable microspheres show potential for effective delivery of epigenetic agents. Citation Format: Jay V. Patel, Kunal P. Desai, Duc P. Do. Formulation of oral microparticulate drug delivery system for cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4340. doi:10.1158/1538-7445.AM2013-4340

Polymeric microparticles-based formulation for the eradication of cutaneous candidiasis: development and characterization

Cutaneous candidiasis is a common topical fungal infection which may be more prominent in patients associated with AIDS. It is usually treated by conventional formulations such as cream, gel, which show various adverse effects on skin along with systemic absorption. To overcome these drawbacks, various novel drug delivery systems have been explored. Poly(lactic-co-glycolic acid) (PLGA)-based microparticulate systems have shown good dermal penetration after topical application. Therefore, in the present study clotrimazole-loaded PLGA microspheres were prepared for targeted dermal delivery. Microspheres were prepared by using a single emulsification (oil-in-water, O/W) evaporation technique and characterized for different parameters. Prepared microparticulate systems were dispersed in Carbopol 934® gel and antifungal activity was carried out on experimentally induced cutaneous candidiasis in immunosuppressed guinea pigs. Particle size of optimized formulation was 2.9 µm along with 74.85% entrapment of drug. Skin retention studies revealed that drug accumulation in the skin was higher with microspheres gel as compared to marketed gel. Confocal microscopy of skin further confirmed penetration of microspheres up to 50 µm into the dermal region. In-vivo antifungal activity studies demonstrated that microsphere gel showed better therapeutic activity, lowest number of cfu/ml was recorded, as compared to marketed gel after 96 h of application. Based on the results of the study, it can be concluded that PLGA microparticles may be promising carriers to deliver clotrimazole intradermally for the treatment of invasive fungal infections.

Chitosan Based Delivery Systems on a Length Scale: Nano to Macro

In recent years, chitosan, a biocompatible natural polymer, having a cellulosic backbone has gained importance in various biomedical applications like wound healing, tissue engineering, surface modifications of implantable devices, and drug delivery. This may be attributed to the versatile chemistry of the polymer. Various chitosan-mediated delivery systems have been developed to improve the bioavailability of drug(s) and be categorized either as nanoparticulate, microparticulate, or macro delivery systems. All these delivery systems have their own advantages and limitation as a delivery vehicle. This review gives an overview of the chitosan-based drug delivery systems.

A phase I study investigating the safety and pharmacokinetics of highly bioavailable curcumin in cancer patients.

290 Background: Curcumin is a natural polyphenol derived from turmeric (Curcuma longa). Growing preclinical data suggests that curcumin could be a promising anticancer drug, however, poor bioavailability has been a challenging problem for its clinical application. To overcome this problem, a new form of curcumin (Theracurmin) was developed using a microparticle and surface-controlled drug delivery system. We evaluated the safety and pharmacokinetics of Theracurmin in combination with gemcitabine-based chemotherapy in cancer patients. Methods: Pancreatic or biliary tract cancer patients who failed standard chemotherapy were eligible. Planned Theracurmin doses comprised Level 0: 100 mg/body/day; Level 1: 200 mg/body/day; and Level 2: 400 mg/body/day. Level 1 was selected as a starting dose, and daily oral Theracurmin was added to standard gemcitabine-based chemotherapy. In addition to plasma curcumin levels, quality of life (QOL) score scaled according to the European Organization for Research and Treatment of Cancer Core Quality of Life Questionnaire (EORTC-QLQ-C30), NF-κB activity, cytokine levels (interleukin-6 and tumor necrosis factor–α), and efficacy were investigated. Results: We enrolled 16 patients between February 2011 and January 2012. Peak plasma curcumin levels (median) after Theracurmin administration were 324 ng/mL (range: 47–1,029) at Level 1 and 440 ng/mL (range: 179–1,380) at Level 2. These values were significantly higher than those in our previous data achieved using 8 g of conventional curcumin. Long systemic exposure to high concentrations of curcumin did not increase the incidence of adverse events. Interestingly, fatigue- and functioning-associated QOL scores significantly improved after Theracurmin administration (p< 0.01). Conclusions: Up to 400 mg/body/day of Theracurmin could safely increase plasma curcumin levels in cancer patients receiving gemcitabine-based chemotherapy. Clinical trial information: 000002950.

Development of tiotropium inhalation formulations for the treatment of chronic obstructive pulmonary disease

Tiotropium, a longer acting anticholinergic bronchodilator, has been widely used for treatment of chronic obstructive pulmonary disease (COPD). To improve the therapeutic effect of tiotropium, we developed various inhalation microparticular formulations of tiotropium using starch, hyaluronate, bovine serum albumin (BSA), and poly(lactide-co-glycolide) (PLGA). All formulations showed ~90 % inhalation efficiency in the lung epithelium of BALB/c mice after initial administration. Interestingly, when compared to other formulations using starch, hyaluronate, and BSA, the inhalation formulation of tiotropium using PLGA showed longer drug residence (up to 7 days) in in vivo lung epithelium. We believe that this microparticle system is expected to improve the treatment efficacy for the patients with COPD by maintaining drug therapeutic effect during the extended period after initial inhalation.

Silica–lipid hybrid (SLH) formulations enhance the oral bioavailability and efficacy of celecoxib: An in vivo evaluation

This study is the first to demonstrate in canines the ability of silica-lipid hybrid (SLH) microparticles to enhance the bioavailability and efficacy of a poorly water-soluble drug after oral administration. Spray-dried SLH microparticles comprising Capmul MCM (mono-diglycerides of C8/C12 fatty acids) and silica nanoparticles (Aerosil® 380) were shown to significantly enhance the fasted state oral bioavailability of celecoxib (CEL) (6.5 fold, relative to an aqueous suspension and more than 2-fold higher relative to the fed state) after oral administration to beagle dogs. Comparable bioavailability was observed between the SLH microparticle formulation and a conventional Capmul lipid solution, however, plasma concentrations were observed to be higher (Cmax, 1.1±0.06 vs. 0.8±0.03μg/mL) (p≤0.05) with the SLH microparticle system. The enhanced bioavailability of CEL observed with the SLH microparticles was reflected in a subsequent efficacy study conducted in an adjuvant-induced arthritis model in the rat. Reduced clinical and histological severity was observed at a dose of 3mg/kg/day, with the progression of arthritic symptoms and tissue damage reduced to a similar degree to that of a higher dose administered at 5mg/kg/day and prepared in an aqueous suspension., The enhanced bioavailability and improved efficacy observed with the SLH microparticles were attributed to the maintenance of CEL in a solubilised form during digestion of the lipid vehicle. We hypothesise that the presence of silica in the formulation may have contributed to the prevention of drug precipitation in the intestinal lumen by providing an alternative binding site for CEL to adsorb to prior to re-solubilisation and absorption. The study highlights the potential utility of novel SLH microparticle formulations as stable dry powders that possess the properties of a lipid-based formulation for the enhanced delivery and efficacy of poorly water-soluble drugs.

Transition between Collective Behaviors of Micromotors in Response to Different Stimuli

We report a Ag(3)PO(4) microparticle system showing collective behaviors in aqueous medium. Transition between two emergent patterns, namely "exclusion" and "schooling", can be triggered by shift in chemical equilibrium upon the addition or removal of NH(3) or in response to UV light. The transitions are consistent with a self-diffusiophoresis mechanism resulting from ion gradients. The reported system is among the few examples of nanomotors that are based on a reversible nonredox reaction and demonstrates new design principles for micro/nanomotors. Potential applications of the reported system in logic gates, microscale pumping, and hierarchical assembly have been demonstrated.

Novel microparticulate systems for the vaginal delivery of nystatin: Development and characterization

To develop more effective antifungal microparticulate therapeutic systems for the treatment of Candida vaginitis, microparticles containing nystatin were elaborated by emulsification/internal gelation method. Three types of microparticles were successfully prepared, alginate microparticles, chitosan and poloxamer 407 coated alginate microparticles. DSC and FT-IR studies were performed to test the efficacy of the method. After physicochemical characterization, mean particle sizes ranged from 36.088μm to 56.146μm. The encapsulation efficiency was found to be similar for alginate and chitosan coated microparticles and lower for poloxamer 407 coated. Optimal mucoadhesive properties in all kind of microparticles where exhibited. Release studies showed the best kinetic parameters for poloxamer 407 coated microparticles. After ex vivo permeation studies through porcine vaginal mucosa, and determination of the amount of nystatin retained as well as microbiologic studies performed, it could be inferred that the developed microparticulate systems offered an antifungal effect against Candida albicans without toxic systemic absorption.

Formulation of microspheres containing Crataegus monogyna Jacq. extract with free radical scavenging activity

Extracts of Crataegus monogyna Jacq. (hawthorn) show an interesting free radical scavenging (FRS) effect, related to their flavonoids content. Unfortunately, their oral administration is affected by their low bioavailability. The aim of this work is to obtain a multiparticulate drug delivery system for hawthorn extracts for oral administration. The extracts from flowering tops (FL) or fruits (FR) of hawthorn were obtained with maceration, using ethanol as an extraction solvent, and their antioxidant activity was evaluated. FL extract showed the highest FRS activity (EC50 3.72 ± 1.21 µg/ml), so it was selected to prepare microparticulate systems by a spray-drying technique, which were characterized by granulometric analysis, scanning electron microscopy–energy dispersive X-ray spectroscopy, confocal fluorescence microscopy and hyperoside content. Antioxidant activity was evaluated before and after gastrointestinal transit in vitro simulation. Results indicate that the microparticulate systems maintained the antioxidant activity of hawthorn also after gastrointestinal transit in vitro simulation, exhibiting properties suitable for oral administration.

In situ forming microparticle implants for delivery of sex steroids in fish: Modulation of the immune response of gilthead seabream by testosterone

Current knowledge on the sensitivity of marine fish to androgenic environmental chemicals is limited, despite the growing interest in the effects of endocrine disrupting chemicals. To study in vivo the effects of testosterone (T) on the fish immune response, we used a microencapsulation implant technique, the in situ forming microparticle system, containing 1mg T/kg body weight (T-ISM), in adult specimens of gilthead seabream (Sparus aurata L.), a species of great economic interest. We demonstrated that implants themselves (without T) have no significant effect on most of the parameters measured. In T-ISM implanted fish, T serum levels reached supraphysiological concentrations accompanied by a slight increase in 11-ketotestosterone and 17β-estradiol levels 21days post-implantation (dpi). Liver and head-kidney samples were processed 7 and 21 dpi to assess T-ISM effect on (i) the mRNA expression of genes involved in the metabolism of steroid hormones and in the immune response, and (ii) phagocyte activities. The expression profile of cytokines, chemokines and immune receptors was altered in T-ISM implanted animals that showed an early pro-inflammatory tendency, and then, a mixed pro-/anti-inflammatory activation during longer exposure. Furthermore, the enhancement of phagocytic activity and the production of reactive oxygen species by leukocytes 21 dpi in T-ISM implanted specimens suggest fine modulation of the innate immune response by T. Taken together, these data demonstrate for the first time the feasibility of using ISM implants in an aquatic species, and provide new data on the role played by T on the immune response in fish.

Application of PEO/Cofactor System on Papermaking Process for Recycled Fibers

Ionic trash in furnish decreases retention and drainage performance of the microparticle retention system using recycled fibers in closed papermaking system. Two retention systems, such as the microparticle system and the PEO/cofactor system, were compared and analyzed to improve retention. The PEO/cofactor system achieved similar retention performance at low addition level as the microparticle system. Optimum ratio of PEO/cofactor dual polymer system was 1:10. Ash retention was increased when using the fixing agent. As the TMP ratio increased, the PEO/cofactor system was more efficient in retention and drainage than the other system. The high molecular weight and non-ionic polymer retention system had less effect on flocculation hindrance than the traditional electrostatic retention system.

A novel dense CO2 supercritical fluid technology for the development of microparticulate delivery systems containing ketoprofen

VarioSol® is an innovative, solvent-free technology able to produce microparticles exploiting near-critical CO2 properties as spraying and cooling agent. The aim of the present work was to evaluate the feasibility to produce in a single processing step by VarioSol® technology, oral ketoprofen-loaded microparticles with gastro-protective properties. The obtained products were powders composed of regular in shape and small in diameter microparticles, characterized by high drug content (40%) and good flow properties. Microparticles were composed by anionic lipids scarcely soluble at acidic pH, blended with gastro-resistant polymers of the methacrylate type. In vitro drug release results indicated that the drug was rapidly delivered from the microparticulate systems in phosphate buffer at pH 6.8, while in acidic medium, the microparticles were able to retard the drug release process but without reaching complete gastro-resistance.However, the results obtained in this study, although non optimal, are not far from the specifications required for gastro-resistant release products (i.e., no more than 10% drug released after 1h at pH 1.0) according to EMA guidelines and represent a good starting point for future formulation development.

Microparticle surface modifications targeting dendritic cells for non-activating applications

Microparticulate systems for delivery of therapeutics to DCs for immunotherapy have gained attention recently. However, reports addressing the optimization of DC-targeting microparticle delivery systems are limited, particularly for cases where the goal is to deliver payload to DCs in a non-activating fashion. Here, we investigate targeting DCs using poly (d lactide-co-glycolide) microparticles (MPs) in a non-stimulatory manner and assess efficacy in vitro and in vivo. We modified MPs by surface immobilizing DC receptor targeting molecules – antibodies (anti-CD11c, anti-DEC-205) or peptides (P-D2, RGD), where anti-CD11c antibody, P-D2 and RGD peptides target integrins and anti-DEC-205 antibody targets the c-type lectin receptor DEC-205. Our results demonstrate the modified MPs are neither toxic nor activating, and DC uptake of MPs in vitro is improved by the anti-DEC-205 antibody, the anti-CD11c antibody and the P-D2 peptide modifications. The P-D2 peptide MP modification significantly improved DC antigen presentation in vitro both at immediate and delayed time points. Notably, MP functionalization with P-D2 peptide and anti-CD11c antibody increased the rate and extent of MP translocation in vivo by DCs and MΦs, with the P-D2 peptide modified MPs demonstrating the highest translocation. This work informs the design of non-activating polymeric microparticulate applications such as vaccines for autoimmune diseases.

Modeling of drug release from biodegradable triple‐layered microparticles

Numerous models that predict drug release from nonerodible reservoir-membrane sphere systems have been presented. Most of these models cater only to a phase of drug release from a constant reservoir. All these models, however, are not applicable to drug release from biodegradable triple-layered microparticle system, in which the drug-loaded core (reservoir) is surrounded by nondrug holding outer layers (membrane). In this article, a mathematical model was developed for ibuprofen release from degradable triple-layered microparticles made of poly(D,L-lactide-co-glycolide, 50:50) (PLGA), poly(L-lactide) (PLLA), and poly(ethylene-co-vinyl acetate, 40 wt % vinyl acetate) (EVA), where ibuprofen was localized within the nonconstant reservoir (EVA core). The model postulated that the drug release through the bulk-degrading PLLA and PLGA layers consisted of two mechanisms: simple diffusional release followed by a degradation-controlled release through a rate-limiting membrane. The proposed model showed very good match with the experimental data of release from microparticles of various layer thicknesses and particle sizes. The underlying drug release mechanisms are dictated by three parameters determined by the model, including constant characteristic of diffusion, end time point of simple diffusion-controlled release and partition coefficient of drug. The presented model is effective for understanding the drug release mechanisms and for the design of this type of dosage form.

Injectable <i>In Situ</i> Forming Microparticles: A Novel Drug Delivery System

Pharmaceutical formulation research has recently been focusing on delivery systems which provide long therapeutic effects and reduced side effects, and involving simplified production stages and facilitated application process. In situ forming microparticle (ISM) systems, one of the latest approach in this field, offer a new encapsulation technique and meet the objectives stated above. Factors such as the carrier used to form the multiparticles, amount and type of drug and the vehicle type can be taken as the main performance criteria for these systems. Ongoing studies have shown that this new multiparticulate drug delivery system is suitable for achieving new implant delivery system with low risk of dose-dumping, capable of being modulated to exhibit varying release patterns, reproducible, easily applicable and welltolerated compared with classically surgical implants.Keywords: Injectable, In situ forming, Microparticle system, Controlled drug delivery.

Behaviour of the Sedimentation in a System of Microparticles

El articulo presenta la determinacion experimental del comportamiento de la velocidad de sedimentacion de un sistema de microparticulas, y a partir de los resultados alcanzados, se evalua si existe alguna diferencia entre el valor del exponente de la funcion de obstruccion determinado por Richardson y Zaki (1954), para el caso de sistemas de microparticulas no coloidales de orden de tamano entre 1.500 nm y 200 nm, se describe ademas el comportamiento de dicho exponente. Conjuntamente, se expone el trabajo de caracter experimental desarrollado bajo la Norma DIN 66111 (1989), utilizando para este una centrifuga analitica, asi como el analisis de los datos extraidos. Los datos mostraron que existe una diferencia entre el valor propuesto por Richardson y Zaki en 1954, respecto a los determinados experimentalmente. Esto permite concluir, que para sistemas de microparticulas menores a un tamano de 1.000 nm, existe un nuevo valor del exponente de la funcion de obstruccion del orden de 11,5. Ademas, se pudo determinar que existe una relacion entre dicho exponente y el tamano medio de las microparticulas que conforman el sistema de particulas que sedimenta.

Modified Polysaccharides as Versatile Materials in Controlled Delivery of Antidegenerative Agents

The mechanisms and factors causing or influencing degenerative diseases require tailor-made solutions. Natural polysaccharides are among the most versatile building units of the novel drug delivery systems. Their properties can be easily tailored to specific needs because they depend not only on the first-order structure, but also on the molecular weight, the type of end-groups and the conformation of the chain. The review presents the current state-of-art in the field of modifications of natural polysaccharides aiming at improving the delivery of anti-degenerative agents. Derivatization includes introducing of ionic or hydrophobic groups in order to adjust polarity or to obtain amphiphilic material, as well as degradable bonds, spacers and targeting moieties. The influence of the modification on the properties of the carrier, such as its size, surface charge, encapsulation efficiency, drug release profile, and stability in vivo, is discussed. Application of the polysaccharide derivatives to enhance the mucoadhesion and to actively target the drug to its site of action is also shown for a variety of carriers: nano and microparticulate systems, coated liposomes, hollow particles and polymer-drug conjugates.