Modified release of beclometasone dipropionate from chitosan-based spray-dried respirable powders

Porous Chitosan/Hydroxyapatite Composite Microspheres for Vancomycin Loading and Releasing

Porous chitosan/hydroxyapatite (Chi-HAp) composite microspheres were prepared in an aqueous solution containing chitosan, calcium nitrate, and ammonium dihydrogen phosphate by using a hydrothermal method at various temperatures. The investigation indicated that temperature significantly impacted the final product's appearance. Hydroxyapatite (HAp) coupled with dicalcium phosphate dihydrate (DCPD) flakes were obviously found at 65 and 70 °C, while the latter gradually disappeared at higher temperatures. Conversely, synthesis at 90 °C led to smaller particle sizes due to the broken chitosan chains. The microspheres synthesized at 75 °C were selected for further analysis, revealing porous structures with specific surface areas of 36.66 m2/g, pores ranging from 3 to 100 nm, and pore volumes of 0.58 cm3/g. Vancomycin (VCM), an antibiotic, was then absorbed on and released from the microspheres derived at 75 °C, with a drug entrapment efficiency of 20% and a release duration exceeding 20 days. The bacteriostatic activity of the VCM/composite microspheres against Staphylococcus aureus increased with the VCM concentration and immersion time, revealing a stable inhibition zone diameter of approximately 4.3 mm from 24 to 96 h, and this indicated the retained stability and efficacy of the VCM during the encapsulating process.

Preparation of an oil suspension containing ondansetron hydrochloride as a sustained release parenteral formulation

Ondansetron hydrochloride (ODS) is a selective 5-hydroxytryptamine type 3 antagonist for nausea and emesis prevention in neoplastic patients. To reduce dosing frequency and side effects and improve patient compliance, a sustained release parenteral formulation of ODS was developed. Microparticles of methylcellulose (MC) and ODS were prepared using the spray-drying method and suspended in oils to form oil suspensions. The formulations were evaluated for residual moisture, drug content, size distribution, DSC, XRD, FTIR, SEM, drug release, and pharmacokinetic studies. The effects of polymers and oils on the drug release were evaluated. MC showed the most prominent sustained release effect among various polymers examined with the optimum MC/ODS ratio of 2:1 (w/w). The particle size of the produced microparticles was in the mean diameter of approximately 3 μm. Physicochemical characterization suggested that ODS existed in an amorphous matrix within the microparticles and interacted with MC via hydrogen bonds. Corn oil was selected as the appropriate oil for suspension due to the sustained release of ODS and the appropriate viscosity. The optimized sustained release formulation of ODS was the corn oil suspension of spray-dried microparticles containing MC and ODS (2:1, w/w). It showed an in vitro drug sustained release up to 120 h, while the oil suspension of ODS without any polymer released the drug within 2 h. Following subcutaneous administration in rats, the optimized formulation could prolong the drug release until 72 h with the enhanced bioavailability in comparison with the ODS solution. The oil suspension of spray-dried microparticles might be an efficient approach for prolongation of the drug effect in the management of nausea and emesis. Graphical abstract.

Microencapsulation of Copper(II) Sulfate in Ionically Cross-Linked Chitosan by Spray Drying for the Development of Irreversible Moisture Indicators in Paper Packaging

Copper(II) sulfate-loaded chitosan microparticles were herein prepared using ionic cross-linking with sodium tripolyphosphate (STPP) followed by spray drying. The microencapsulation process was optimal using an inlet temperature of 180 °C, a liquid flow-rate of 290 mL/h, an aspiration rate of 90%, and an atomizing gas flow-rate of 667 nL/h. Chitosan particles containing copper(II) sulfate of approximately 4 µm with a shrunken-type morphology were efficiently attained and, thereafter, fixated on a paper substrate either via cross-linking with STPP or using a chitosan hydrogel. The latter method led to the most promising system since it was performed at milder conditions and the original paper quality was preserved. The developed cellulose substrates were reduced and then exposed to different humidity conditions and characterized using colorimetric measurements in order to ascertain their potential as irreversible indicators for moisture detection. The results showed that the papers coated with the copper(II) sulfate-containing chitosan microparticles were successfully able to detect ambient moisture shown by the color changes of the coatings from dark brown to blue, which can be easily seen with the naked eye. Furthermore, the chitosan microparticles yielded no cytotoxicity in an in vitro cell culture experiment. Therefore, the cellulose substrates herein developed hold great promise in paper packaging as on-package colorimetric indicators for monitoring moisture in real time.

Spray-dried alginate microparticles for potential intranasal delivery of ropinirole hydrochloride: development, characterization and histopathological evaluation

Ropinirole hydrochloride (RH) is an anti-Parkinson drug with relativity low oral bioavailability owing to its extensive hepatic first pass metabolism. Spray-dried mucoadhesive alginate microspheres of RH were developed and characterized followed by histopathological evaluation using nasal tissue isolated from sheep. Spherical microparticles having high product yield (around 70%) were obtained when the inlet temperature of spray drying was 140 °C. Fourier Transform Infrared (FTIR) studies revealed the compatibility of the drug with the polymer, and scanning electron microscopy (SEM) showed that drug-loaded microparticles were spherical, and the apparent surface roughness was inversely related to the ratio of polymer to drug. Furthermore, size of the spray-dried particles were in the range of 2.5-4.37 µm, depending on formulation. All formulations had high drug encapsulation efficiencies (101-106%). Drug loaded into the polymeric particles was in the amorphous state and drug molecules were molecularly dispersed in the polymeric matrix of the microparticles which were revealed by X-ray diffraction and differential scanning calorimetry (DSC), respectively. The in vitro drug release was influenced by polymer concentration. Histopathological study demonstrated that RH-loaded sodium alginate microparticles was safe to nasal epithelium. In conclusion, spray drying of RH using sodium alginate polymer has produced microparticles of suitable characteristics for potential intranasal administration.

Process optimization of spray-dried fanhuncaoin powder for pulmonary drug delivery and its pharmacokinetic evaluation in rats

The optimization of process parameters of spray-dried powder containing fanhuncaoin, a newly discovered anti-inflammatorily active phenolic acid isolated from Chinese herb, was conducted using response surface methodology (RSM). The experimental results were fitted into partial cubic polynomial model to describe and predict the response quality in terms of the final angle of repose, aerodynamic diameter, respirable fraction (RF), and yield. The recommended optimum spray-drying parameters for the development of fanhuncaoin powder with optimum quality were 110 °C inlet temperature, 0.50 m³/min aspiration speed, and 7.95 ml/min feed flow rate. The obtained optimum process parameters were employed for the production of spray-dried fanhuncaoin powder and to check the validity of the partial cubic model. Small and insignificant deviations were found between the predicted values and the experimental ones, showing the efficiency of the model in predicting the quality attributes of fanhuncaoin powder. The optimized powder was further examined for its pharmacokinetic properties in rats. A UPLC/MS assay was used to determine plasma fanhuncaoin concentration. Statistical analysis demonstrated that there was no significant difference in the t_1/2 and dose-normalized C_max and AUC as well as other pharmacokinetic parameters between the groups dosed differently following intratracheal administration (p > .05), indicating that fanhuncaoin followed linear kinetics. The pharmacokinetic parameters of fanhuncaoin after intratracheal administration differed significantly from the ones observed after intravenous administration (p < .05). The lower values of C_max and AUC_(0-∞) obtained following intratracheal administration may lead to effective drug concentrations at the target site with minimal systemic bioavailability and side effects.

Recent advances in chitosan-based nanoparticulate pulmonary drug delivery

The advent of biodegradable polymer-encapsulated drug nanoparticles has made the pulmonary route of administration an exciting area of drug delivery research. Chitosan, a natural biodegradable and biocompatible polysaccharide has received enormous attention as a carrier for drug delivery. Recently, nanoparticles of chitosan (CS) and its synthetic derivatives have been investigated for the encapsulation and delivery of many drugs with improved targeting and controlled release. Herein, recent advances in the preparation and use of micro-/nanoparticles of chitosan and its derivatives for pulmonary delivery of various therapeutic agents (drugs, genes, vaccines) are reviewed. Although chitosan has wide applications in terms of formulations and routes of drug delivery, this review is focused on pulmonary delivery of drug-encapsulated nanoparticles of chitosan and its derivatives. In addition, the controversial toxicological effects of chitosan nanoparticles for lung delivery will also be discussed.

Effects of Chemical Conjugation of l-Leucine to Chitosan on Dispersibility and Controlled Release of Drug from a Nanoparticulate Dry Powder Inhaler Formulation

This study investigated l-leucine-conjugated chitosan as a drug delivery vehicle in terms of dispersibility and controlled release from a nanoparticulate dry powder inhaler (DPI) formulation for pulmonary delivery using diltiazem hydrochloride (DH) as the model drug. DH-loaded nanoparticles of chitosan and conjugate were prepared by water-in-oil emulsification followed by glutaraldehyde cross-linking. Nanoparticles were characterized by dynamic light scattering for particle size, X-ray photoelectron spectroscopy for surface composition, and twin stage impinger for drug dispersibility. The controlled release of DH was studied in phosphate-buffered saline (pH 7.3 ± 0.2, 37 °C) using UV spectrophotometry. The fine particle fractions of conjugated chitosan with and without drug were higher than those of nonconjugated chitosan nanoparticles. The conjugate nanoparticles were superior to those of unmodified chitosan in drug loading, entrapment efficiency, and controlled release profile. The higher dispersibility was attributed to the amphiphilic environment of the l-leucine conjugate and hydrophobic cross-links, and the release profile reflects the greater swelling. The conjugated chitosan nanoparticles could be useful, after appropriate testing for biodegradability and toxicity, as an alternative carrier for lung drug delivery with enhanced aerosolization and prolonged drug release from nanoparticulate DPI formulations.

Development and Evaluation of Chitosan Microparticles Based Dry Powder Inhalation Formulations of Rifampicin and Rifabutin

BACKGROUND

The lung is the primary entry site and target for Mycobacterium tuberculosis; more than 80% of the cases reported worldwide are of pulmonary tuberculosis. Hence, direct delivery of anti-tubercular drugs to the lung would be beneficial in reducing both, the dose required, as well as the duration of therapy for pulmonary tuberculosis. In the present study, microsphere-based dry powder inhalation systems of the anti-tubercular drugs, rifampicin and rifabutin, were developed and evaluated, with a view to achieve localized and targeted delivery of these drugs to the lung.

METHODS

The drug-loaded chitosan microparticles were prepared by an ionic gelation method, followed by spray-drying to obtain respirable particles. The microparticles were evaluated for particle size and drug release. The drug-loaded microparticles were then adsorbed onto an inhalable lactose carrier and characterized for in vitro lung deposition on an Andersen Cascade Impactor (ACI) followed by in vitro uptake study in U937 human macrophage cell lines. In vivo toxicity of the developed formulations was evaluated using Sprague Dawley rats.

RESULTS

Both rifampicin and rifabutin-loaded microparticles had MMAD close to 5 μm and FPF values of 21.46% and 29.97%, respectively. In vitro release study in simulated lung fluid pH 7.4 showed sustained release for 12 hours for rifampicin microparticles and up to 96 hours for rifabutin microparticles, the release being dependent on both swelling of the polymer and solubility of the drugs in the dissolution medium. In vitro uptake studies in U937 human macrophage cell line suggested that microparticles were internalized within the macrophages. In vivo acute toxicity study of the microparticles in Sprague Dawley rats revealed no significant evidence for local adverse effects.

CONCLUSION

Thus, spray-dried microparticles of the anti-tubercular drugs, rifampicin and rifabutin, could prove to be an improved, targeted, and efficient system for treatment of tuberculosis.

Inhalable DNase I microparticles engineered with biologically active excipients

Highly viscous mucus poses a big challenge for the delivery of particulates carrying therapeutics to patients with cystic fibrosis. In this study, surface modifying DNase I loaded particles using different excipients to achieve better lung deposition, higher enzyme stability or better biological activity had been exploited. For the purpose, controlled release microparticles (MP) were prepared by co-spray drying DNase I with the polymer poly-lactic-co-glycolic acid (PLGA) and the biocompatible lipid surfactant 1,2-dipalmitoyl-Sn-phosphatidyl choline (DPPC) using various hydrophilic excipients. The effect of the included modifiers on the particle morphology, size, zeta potential as well as enzyme encapsulation efficiency, biological activity and release had been evaluated. Powder aerosolisation performance and particle phagocytosis by murine macrophages were also investigated. The results showed that more than 80% of enzyme activity was recovered after MP preparation and that selected surface modifiers greatly increased the enzyme encapsulation efficiency. The particle morphology was greatly modified altering in turn the powders inhalation indices where dextran, ovalbumin and chitosan hydrochloride increased considerably the respirable fraction compared to the normal hydrophilic carriers lactose and PVP. Despite of the improved aerosolisation caused by chitosan hydrochloride, yet retardation of chitosan coated particles in artificial mucus samples discouraged its application. On the other hand, dextran and polyanions enhanced DNase I effect in reducing cystic fibrosis mucus viscosity. DPPC proved good ability to reduce particles phagocytic uptake even in the presence of the selected adjuvants. The prepared MP systems were biocompatible with lung epithelial cells. To conclude, controlled release DNase I loaded PLGA-MP with high inhalation indices and enhanced mucolytic activity on CF sputum could be obtained by surface modifying the particles with PGA or dextran.

Synthesis and characterization of gibberellin-chitosan conjugate for controlled-release applications

Controlled release formulations (CRFs) are promising in improving the efficiency of pesticide and minimizing the spreading of hazardous residues in environment. By coupling with the pesticide covalently, chitosan can be used as a carrier material for the vulnerable ingredient. For the first time, gibberellic acid (GA3), one of plant growth regulators, was attached to chitosan (CS) to form a GA3-CS conjugate via the formation of an amide bound using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide. The novel conjugate was structurally characterized by fourier transform infrared spectroscopy, ultraviolet spectrophotometer, and thermal gravimetric analysis. Effects of pH, temperature, and UV irradiation on the release of this conjugate were investigated. The results showed that the new conjugate had a remarkable modification degree for CS (more than 60%, w/w) and the optimal coupling conditions were defined as: the molar ratio of GA3:EDC/NHS:CS was 1:1.2:1.2, at pH 6.0 for 24 h. The release data showed the novel conjugate protected GA3 against photo- and thermal-degradation effectively and the concentration of GA3 in GA3-CS kept unchangeable about 60 d in different pH conditions. Compared with GA3 technical, the conjugate had better water solubility and stability and have potential applications. The present study also provides a novel preparation method of CRFs comprising a pesticide with long duration, sustained-release performance and good environmental compatibility. This method may be extended to other pesticides that possess a carboxyl group.

A PERSPECTIVE VIEW ON THE PREPARATION OF MICRO- AND NANOPARTICULATES OF BIOMATERIALS FROM ELECTROSTATIC AND ULTRASONIC METHODS

Developments on tissue engineering, especially on tissue regeneration and drug delivery, demand also developments on biomaterials. Research on the preparation methods of biomaterials has exhibited remarkable advances in the recent years. Natural biomaterials, such as chitosan and collagen, or synthetic materials like poly(lactic acid) can be shaped in various forms. The parameters involved in the fabrication processes provide methodologies for control of the materials' properties, such as morphology, biodegradability, mechanical strength, and adhesion. As new applications develop for these materials, the preparation methods have to be optimized to achieve the desired material properties. These properties mostly not only mimic the conditions in the human body, but also may divert the microenvironment of cells in the diseased area in order to promote faster or guided healing and tissue regeneration. This review pays attention on some of the fabrication methods for biomaterial particulates of sizes in the micro- and nanoscale. The views expressed here focus on the many years of experience of the authors with electrostatic and ultrasonic fabrication methods. These methods are still under development and up to now can produce particulates of various sizes down to the nanometer scale with narrow size distributions. Such biomaterials that have extraordinary properties may provide ways for the development of remarkable biomedical applications.

Therapeutic aerosol bioengineering of targeted, inhalable microparticle formulations to treat Mycobacterium tuberculosis (MTb)

Therapeutic aerosol bioengineering (TAB) of Mycobacterium tuberculosis (MTb) therapies using inhalable microparticles offers a unique opportunity to target drugs to the site of infection in the alveolar macrophages, thereby increasing dosing in the lungs and limiting systemic exposure to often toxic drugs. Previous work by us used sophisticated, high content analysis to design the optimal poly(lactide-co-glycolic) acid (PLGA) microparticle for delivery of drugs to alveolar macrophages. Herein, we applied this technology to three different anti-MTb drugs. These formulations were then tested for encapsulation efficiency, drug-release, in vitro killing against MTb and aerosol performance. Methods for encapsulating each of the drugs in the PLGA microparticles were successfully developed and found to be capable of controlling the release of the drug for up to 4 days. The efficacy of each of the encapsulated anti-MTb drugs was maintained and in some cases enhanced post-encapsulation. A method of processing these drug-loaded microparticles for inhalation using standard dry powder inhaler devices was successfully developed that enabled a very high respirable dose of the drug to be delivered from a simple dry powder inhaler device. Overall, TAB offers unique opportunities to more effectively treat MTb with many potential clinical and economic benefits resulting.

Optimization and characterization of dry powder of fanhuncaoin for inhalation based on selection of excipients

In this study, dry powder formulations for inhalation of fanhuncaoin, a newly discovered antiinflammatorily active compound isolated from Chinese herb, were designed to optimize the composition and further explore the relationship between the composition, the physical properties and the aerosolization performance. Dry powders were prepared by spray-drying using leucine, chitosan, chitosan oligosaccharide and dipalmitoyl phosphatidylcholine (DPPC) as excipients. Following spray-drying, resultant powders were characterized using scanning electron microscopy, tapped density analysis, laser diffractometry, thermogravimetric analysis and differential scanning calorimetry. The aerosol behaviour of the powders was studied in a Twin Stage Impinger at an airflow rate of 60 l/min using a HandiHaler® inhaler device. Results revealed that the nature and the relative proportion of the excipients greatly influenced the physical characteristics of the powders and their aerodynamic behavior. Among the combinations tested, the composition ratio of fanhuncaoin/leucine/chitosan/chitosan oligosaccharide/DPPC of 10/45/33.75/11.25/0.4 (w/w/w/w/w) prepared in a total solid mass of 1% (w/v) formulation was found to be particularly optimal and exhibited a tapped density of 0.44 g/cm³, an aerodynamic diameter of 2.24 µm and an respirable fraction of 51.29%. In conclusion, optimization of the aerosolization properties of inhalation dry powders could be achieved by appropriately selecting the composition of the particles.

Systemic and mucosal delivery of drugs within polymeric microparticles produced by spray drying

Encapsulation of therapeutic and diagnostic materials into polymeric particles is a means to protect and control or target the release of active substances such as drugs, vaccines, and genetic material. In terms of mucosal delivery, polymeric encapsulation can be used to promote absorption of the active substance, while particles can improve the half-life of drugs administered systemically. Spray drying is an attractive technology used to produce such microparticles, because it combines both the encapsulation and drying steps in a rapid, single-step operation. Even so, spray drying is not classically associated with processes used for drug and therapeutic material encapsulation, since elevated temperatures could potentially denature the active substance. However, a comprehensive review of the literature revealed a number of studies demonstrating that spray drying can be used to produce microparticulate formulations with labile therapeutics. Polymers commonly employed include synthetics such as methacrylic copolymers and polyesters, and natural materials including chitosan and alginate. Drugs and active substances are diverse and included antibiotics, anti-inflammatory agents, and chemotherapeutics. Regarding the delivery of spray-dried particles, the pulmonary, oral, colonic, and nasal mucosal routes are often investigated because they offer a convenient means of administration, which promotes physician and patient compliance. In addition, spray drying has been widely used to produce polymeric microparticles for systemic delivery in order to control the delivery of drugs, vaccines, or genetic material that may exhibit poor pharmacokinetic profiles or pose toxicity concerns. This review presents a brief introduction to the technology of spray drying and outlines the delivery routes and the applications of spray-dried polymeric microparticles.

Preparation of zolmitriptan-chitosan microparticles by spray drying for nasal delivery

The objective of this study was to use spray drying to prepare mucoadhesive dry powders of the antimigraine drug, zolmitriptan, in combination with the natural polymer, chitosan, for nasal administration. The effect of type, molecular weight, and proportion of chitosan on the powder and particle characteristics was also studied. Solutions containing different proportions of chitosans were prepared and spray dried. The chemical stability and content of the drug were determined by HPLC. The morphology and size range of the microparticles were also determined. Solid-state analysis was undertaken using thermal methods (DSC/MDSC and TGA), powder X-ray diffraction (PXRD), and Fourier transform infra-red spectroscopy (FT-IR). The drug release profiles were investigated and the time required to reach maximum solution concentrations (T(max)) was used for comparison. The drug was chemically stable, with a 93-105% loading in the microparticles. The microparticles were spherical with a narrow size distribution, irrespective of the formulation. Phase separation was observed for formulations containing less than 90% (w/w) chitosan, irrespective of the type. In contrast, in the formulation containing 90% (w/w) chitosan, the drug was molecularly dispersed. FT-IR studies showed that the bands corresponding to intermolecular hydrogen bonding were broader and more diffuse when zolmitriptan was amorphous. The formation of a hydrogen bond between drug and chitosans was also observed. T(max) increased as the proportion of chitosan decreased, and was proportional to the molecular weight of the chitosan in the formulation containing 90% (w/w) chitosan. Spray drying is a suitable technique for making mucoadhesive dry powders of zolmitriptan and chitosan for nasal application. The dispersion and release of the drug was affected by the properties and composition of the chitosan.