Spray drying formulation of albendazole microspheres by experimental design.In vitro–in vivostudies

Advances in Polysaccharide-Based Oral Colon-Targeted Delivery Systems: The Journey So Far and the Road Ahead

Various colon-targeted oral delivery systems have been explored so far to treat colorectal diseases, including timed-release systems, prodrugs, pH-based polymer coatings, and microflora-triggered systems. Among them, the microbially triggered system has gained attention. Among various oral colon-targeted delivery systems discussed, the polysaccharide-based colon-targeted delivery system has been found to be quite promising as polysaccharides remain unaffected by gastric as well as upper intestine milieu and are only digested by colonic bacteria upon reaching the colon. The major bottleneck associated with this delivery is that non-suitability of this system during the diseased state due to decrease in bacterial count at that time. This causes the failure of delivery system to release the drug even at colonic site as the polysaccharide matrix/coat cannot be digested properly due to lack of bacteria. The co-administration of probiotics is reported to compensate for the bacterial loss besides facilitating site-specific release. However, this research is also limited at the preclinical level. Hence, efforts are required to make this technology scalable and clinically applicable. This article entails in detail various oral colon-targeted delivery systems prepared so far, as well as the limitations and benefits of polysaccharide-based oral colon-targeted delivery systems.

Experimental design and optimization of a novel dual-release drug delivery system with therapeutic potential against infection with Helicobacter pylori

The objective of this study was to develop clarithromycin-loaded lipid nanocarriers and incorporate them into microcapsules for pH-specific localized release of clarithromycin in the Helicobacter pylori microenvironment in order to obtain a gastro-retentive and pH-sensitive formulation. A Plackett-Burman design was applied to identify the effect of 5 factors on 3 responses. Then, a central composite design was applied to estimate the most important factors leading to the best compromise between lower particle size, polydispersity index and particle size changes. The optimized clarithromycin-loaded nanocapsules were employed to generate microcapsules by different methodologies. Nanocarriers and microcapsules were characterized in vitro. Experimental design and conditions were optimized to obtain nanocapsules of around 100 nm by a modified phase inversion-based process. High particle size homogeneity and high stability were achieved. At 4 °C both optimized lipid nanocapsules were stable during at least 365 days, confirming stability under those conditions. Clarithromycin incorporation in the nanocarrier was effective. Both types of microcoating were evaluated regarding their pH sensitivity. Spray drying microcapsules exhibited similar and uncontrolled release profiles at pH 2 and 7.4. Alternatively, when microcoatings were generated using an Encapsulator, release was insignificant at pH 2, while at pH 7.4 release was triggered, and appeared more appropriate to formulate microcapsules that release nanocarriers under pH neutral Helicobacter pylori microenvironment conditions, thereby permitting effective drug delivery in infected locations. The release of clarithromycin from lipid nanocarrier loaded microcapsules was pH-sensitive suggesting that this could be an effective strategy for clarithromycin delivery to the Helicobacter pylori microenvironment. Clarithromycin nanocapsules with and without microcoating showed a high anti-Helicobacter pylori activity in vitro.

Pectin Microspheres: Synthesis Methods, Properties, and Their Multidisciplinary Applications

There is great contemporary interest in using cleaner technologies through green chemistry and utilizing biopolymers as raw material. Pectin is found on plant cell walls, and it is commonly extracted from fruit shells, mostly apples or citrus fruits. Pectin has applications in many areas of commercial relevance; for this reason, it is possible to find available information about novel methods to transform pectin and pursuing enhanced features, with the structuring of biopolymer microspheres being highly cited to enhance its activity. The structuring of polymers is a technique that has been growing in recent decades, due to its potential for diverse applications in various fields of science and technology. Several techniques are used for the synthesis of microspheres, such as ionotropic gelation, extrusion, aerosol drying, or emulsions, with the latter being the most commonly used method based on its reproducibility and simplicity. The most cited applications are in drug delivery, especially for the treatment of colon diseases and digestive-tract-related issues. In the industrial field, it is used for protecting encapsulated compounds; moreover, the environmental applications mainly include the bioremediation of toxic substances. However, there are still many possibilities for expanding the use of this biopolymer in the environmental field.

Effect of Genotype and Sex of the Host on the Bioavailability of Novel Albendazole Microcrystals Based on Chitosan and Cellulose Derivatives

Albendazole (ABZ), an anthelmintic compound widely used in the treatment of systemic nematode infections, is included in the list of class II drugs based on the Biopharmaceutical Classification System. ABZ has limited effectiveness due to its poor water solubility and consequent low bioavailability. Bioavailability of novel ABZ microcrystals based on hydroxyethylcellulose (S4A) or chitosan (S10A) was studied in male and female mice of two inbred lines, from the murine CBi-IGE model of trichinellosis, differing in susceptibility to this parasitosis (line CBi/L, resistant; line CBi+, susceptible). ABZ microcrystals were administered orally, and albendazole sulfoxide (ABZSO) was quantified in plasma by high-performance liquid chromatography. Mice given the microcrystals showed a significant increase in maximum plasmatic concentration (C_max) compared with those receiving pure ABZ (P < 0.01). In both genotypes, males and females given S4A had higher C_max than those receiving S10A (P < 0.05). CBi/L showed a greater C_max than CBi+ (significantly different only in females treated with S4A (P = 0.001)). CBi/L females attained a higher C_max than males (P < 0.05). No sex effect was observed for this variable in CBi+ (P > 0.05). The results of the pharmacokinetic analysis indicate that the microcrystalline formulations optimize ABZ bioavailability, both in males and females, S4A being the best system in CBi/L mice and S10A in CBi+. In summary, the microcrystals increased ABZ bioavailability, and under the conditions of this investigation, both host genotype and sex influenced the pharmacokinetic parameters measured.

Quality Risk Management and Quality by Design for the Development of Diclofenac Sodium Intra-articular Gelatin Microspheres

The aim of the present study was to evaluate the development of an intra-articular nonsteroidal anti-inflammatory drug gelatin microsphere formulation based on quality risk management and quality by design approaches. Specifically, after setting the quality target product profile and the critical quality attributes, risk assessment was performed by constructing Ishikawa fishbone diagrams based on preliminary hazard analysis. A Plackett-Burman screening experimental design was applied in order to identify the factors (previously classified by risk assessment analysis as having high risk of failure) having a statistically significant impact on the formation of gelatin microspheres. Particle size, polydispersity index, and drug loading were used as responses, while diclofenac sodium was selected as a model drug. All drug-loaded gelatin microspheres were prepared by emulsion-crosslinking process. Screening results showed that gelatin type, surfactant type and quantity, oil phase type, emulsification speed, and glutaraldehyde's concentration had a statistically significant impact on microsphere's final and intermediate critical quality attributes. A design space was then constructed based on central composite design overlaying contour plots, while verification experiments for the optimum suggested formulation (derived from a set control strategy) showed good agreement between the predicted and the experimentally observed results. In addition, the physicochemical characterization of the optimum formulation showed the formation of significant molecular interactions between the drug and the gelatin matrix, leading to the complete amorphization of diclofenac within the microsphere structure, while dissolution release experiments showed a biphasic release profile which extended the drug's release for up to 30 days, governed by a Fickian diffusion release mechanism.

Synthesis and characterization of mesoporous SBA-15 and SBA-16 as carriers to improve albendazole dissolution rate

Albendazole (ABZ, anti-parasitic active pharmaceutical ingredient) is a crystalline low water-soluble drug, thus the dissolution rate in gastrointestinal fluids is limited. Consequently, the improvement of the water solubility and dissolution rate of ABZ implies a great challenge for a more efficient treatment of hydatidosis. In this context, SBA-15 and SBA-16 ordered mesoporous silica materials were synthetized and loaded with ABZ. X-ray diffraction, FT-IR spectroscopy, nitrogen physisorption manometry, particle size distribution and scanning electronic microscopy were used to characterize unloaded and loaded materials (ABZ/SBA-15 and ABZ/SBA-16). The loaded ABZ amount in the carriers was estimated by elemental analysis. For the loaded materials, the drug solubility and release profile were evaluated. In addition, mathematical models were compared to explain the dissolution kinetics of ABZ from mesoporous solids. ABZ was successfully loaded into the mesopores. The amorphous state of the adsorbed ABZ was confirmed by differential scanning calorimetry that resulted in a notable increment in the dissolution rate compared to crystalline ABZ. Drug release behaviors were well simulated by the Weibull model for ABZ/SBA-15 and by the Gompertz function for pure ABZ and ABZ/SBA-16. The SBA-15 carrier exhibited the highest drug loading and dissolution rate becoming a promising material to improve ABZ bioavailability.

Synthesis and characterization of a new cyclodextrin derivative with improved properties to design oral dosage forms

This work aimed to synthesize a novel β-cyclodextrin derivative, itaconyl-β-cyclodextrin to evaluate whether albendazole inclusion complexes with the new β-cyclodextrin derivative-improved albendazole dissolution efficiency and its anthelminthic activity. The new derivative was thoroughly evaluated and characterized, and an average degree of substitution of 1.4 per cyclodextrin molecule was observed. Albendazole:itaconyl-β-cyclodextrin complexes were prepared by spray drying procedures and investigated using phase solubility diagrams, dissolution efficiency, X-ray diffraction, differential scanning calorimetry, Fourier transform infrared, scanning electronic microscopy, mass spectrometry, and nuclear magnetic resonance spectroscopy. Phase solubility diagrams and mass spectrometry studies showed that the inclusion complex was formed in an equimolar ratio. Stability constant values were 602 M^-1 in water, and 149 M^-1 in HCl 0.1 N. Nuclear magnetic resonance experiments of the inclusion complex showed correlation signals between the aromatic and propyl protons of albendazole and the itaconyl-β-cyclodextrin inner protons. The studies indicated solid structure changes of albendazole included in itaconyl-β-cyclodextrin. The maximum drug release was reached at 15 min, and the inclusion complex solubility was 88-fold higher than that of the pure drug. The in vitro anthelmintic activity assay showed that the complex was significantly more effective than pure albendazole.

Development and characterization of benznidazole nano- and microparticles: A new tool for pediatric treatment of Chagas disease?

Benznidazole (BNZ) is the drug of choice for the treatment of Chagas disease in many countries. However, its low water solubility produces low and/or variable oral bioavailability. Thus, the aim of this work was to formulate micro- and nanoparticles based on Eudragit^® RS PO and Eudragit^® RL PO as a convenient approach to increase the dissolution rate of BNZ. The microparticles were obtained by means of spray-drying process while the nanoparticles were prepared through the nanoprecipitation technique and further freeze-drying. The results indicated that nanoparticles were obtained in 86% yield while microparticles were obtained in 68% yield. In both cases, the encapsulation efficiency of particles was greater than 78% while drug loading capacity was nearly 24% w/w and 18% w/w, after spray-drying and freeze-drying procedures, respectively. Images of scanning electron microscopy showed that the particles obtained by spray-drying and freeze-drying were in the micrometer and nanometer scale, respectively. FT-IR spectra of BNZ-loaded particles obtained by both methods showed characteristic bands of BNZ confirming that part of drug remained on their surface. Thermal analysis revealed that the drug crystallinity after both methods decreased. Physical stability evaluation of the nanoparticles confirmed that Pluronic^® F68 was suitable to keep the particles size in a range of 300 nm after 70 days storage at 4 ± 2 °C. In-vitro release studies showed increased dissolution rate of drug from the particles obtained by both methods respect to untreated BNZ. The kinetics of drug release in acid media followed the Higuchi kinetics indicating drug diffusion mechanism from particles.

Composite Microparticles Based on Natural Mucoadhesive Polymers with Promising Structural Properties to Protect and Improve the Antifungal Activity of Miconazole Nitrate

Oropharyngeal candidiasis is a recurrent oral infection caused by Candida species. Gel formulation containing miconazole nitrate is the most common approach for treating oral candidiasis. However, traditional oral topical antifungal therapies have many limitations, including short contact time with the oral mucosa and the necessity to administrate various doses per day. Thus, the aim of this work was to formulate composited microparticulated systems based on combinations of mucoadhesive cationic, anionic, and nonionic polymers that could protect and modify the drug release rate and therefore avoid a fast dilution of the drug by saliva. Microparticulated systems were prepared by the spray drying method employing chitosan, gelatin, and hydroxypropyl methylcellulose. The morphology of the systems was investigated by scanning electron microscopy; drug crystallinity was studied by X-ray, while interactions between polymers were analyzed by infrared spectroscopy. Drug release and halo zone test were employed to analyze the release and activity of the systems loaded with miconazole against Candida albicans cultures. The most appropriate microparticulated system was the one based on chitosan and gelatin which showed homogeneous morphology (mean size of 1.7 ± 0.5 μm), a protective effect of the drug, and better antifungal effect against Candida culture than miconazole nitrate and the other assayed systems. Taking into account these results, this approach should be seriously considered for further evaluation of its safety and in vivo efficacy to be considered as an alternative therapeutic system for the treatment of oral candidiasis.

Non-invasive strategies for targeting the posterior segment of eye

The safe and effective treatment of eye diseases has been remained a global myth. Several advancements have been done and various drug delivery and treatment techniques have been suggested. The Posterior segment disorders are the leading cause of visual impairments and blindness. Targeting the therapeutic agents to the anterior and posterior segments of the eye has attracted extensive attention from the scientific community. Significant key factors in the success of ocular therapy are the development of safe, effective, economic and non-invasive novel drug delivery systems. These specialized non-invasive ocular drug delivery systems revolutionized the drug delivery strategies by overcoming the limitations, provided targeted delivery to the ocular tissues by avoiding larger doses, and reducing the toxicity encountered by the conventional approaches. These non-invasive systems are fabricated by ingredients encompassing biodegradability, biocompatibility, mucoadhesion, solubility and permeability enhancement and stimuli responsiveness. The variety of routes are utilized to provide minimally invasive drug delivery to the patients without any discomfort and pain. This review is focused on the brief introduction, types, significance, preparation techniques, components and mechanism of drug release of non-invasive systems, including in situ gelling systems, microspheres, iontophoresis, nanoparticles, nanosuspensions and specialized novel emulsions.

Albendazole Microcrystal Formulations Based on Chitosan and Cellulose Derivatives: Physicochemical Characterization and In Vitro Parasiticidal Activity in Trichinella spiralis Adult Worms

The oral route has notable advantages to administering dosage forms. One of the most important questions to solve is the poor solubility of most drugs which produces low bioavailability and delivery problems, a major challenge for the pharmaceutical industry. Albendazole is a benzimidazole carbamate extensively used in oral chemotherapy against intestinal parasites, due to its extended spectrum activity and low cost. Nevertheless, the main disadvantage is the poor bioavailability due to its very low solubility in water. The main objective of this study was to prepare microcrystal formulations by the bottom-up technology to increase albendazole dissolution rate, in order to enhance its antiparasitic activity. Thus, 20 novel microstructures based on chitosan, cellulose derivatives, and poloxamer as a surfactant were produced and characterized by their physicochemical properties and in vitro biological activity. To determine the significance of type and concentration of polymer, and presence or absence of surfactant in the crystals, the variables area under the curve, albendazole microcrystal solubility, and drug released (%) at 30 min were analyzed with a three-way ANOVA. This analysis indicated that the microcrystals made with hydroxyethylcellulose or chitosan appear to be the best options to optimize oral absorption of the active pharmaceutical ingredient. The in vitro evaluation of anthelmintic activity on adult forms of Trichinella spiralis identified system S10A as the most effective, of choice for testing therapeutic efficacy in vivo.

Advantages and challenges of the spray-drying technology for the production of pure drug particles and drug-loaded polymeric carriers

Spray-drying is a rapid, continuous, cost-effective, reproducible and scalable process for the production of dry powders from a fluid material by atomization through an atomizer into a hot drying gas medium, usually air. Often spray-drying is considered only a dehydration process, though it also can be used for the encapsulation of hydrophilic and hydrophobic active compounds within different carriers without substantial thermal degradation, even of heat-sensitive substances due to fast drying (seconds or milliseconds) and relatively short exposure time to heat. The solid particles obtained present relatively narrow size distribution at the submicron-to-micron scale. Generally, the yield% of spray-drying at laboratory scale with conventional spray-dryers is not optimal (20-70%) due to the loss of product in the walls of the drying chamber and the low capacity of the cyclone to separate fine particles (<2 μm). Aiming to overcome this crucial drawback in early development stages, new devices that enable the production of submicron particles with high yield, even for small sample amounts, have been introduced into the market. This review describes the most outstanding advantages and challenges of the spray-drying method for the production of pure drug particles and drug-loaded polymeric particles and discusses the potential of this technique and the more advanced equipment to pave the way toward reproducible and scalable processes that are critical to the bench-to-bedside translation of innovative pharmaceutical products.