PLGA, chitosan or chitosan-coated PLGA microparticles for alveolar delivery?

Orally administered docetaxel-loaded chitosan-decorated cationic PLGA nanoparticles for intestinal tumors: formulation, comprehensive in vitro characterization, and release kinetics

Intestinal cancers are the third most lethal cancers globally, beginning as polyps in the intestine and spreading with a severe metastatic tendency. Chemotherapeutic drugs used in the treatment of intestinal tumors are usually formulated for parenteral administration due to poor solubility and bioavailability problems. Pharmaceutically, clinical failure due to a drug's wide biodistribution and non-selective toxicity is one of the major challenges of chemotherapy. In addition, parenteral drug administration in chronic diseases that require long-term drug use, such as intestinal tumors, is challenging in terms of patient compliance and poses a burden in terms of health economy. Especially in the field of chemotherapy research, oral chemotherapy is a subject that has been intensively researched in recent years, and developments in this field will provide serious breakthroughs both scientifically and socially. Development of orally applicable nanodrug formulations that can act against diseases seen in the distant region of the gastrointestinal tract (GIT), such as intestinal tumor, brings with it a series of difficulties depending on the drug and/or GIT physiology. The aim of this study is to develop an oral nanoparticle drug delivery system loaded with docetaxel (DCX) as an anticancer drug, using poly(lactic-co-glycolic acid) (PLGA) as nanoparticle material, and modified with chitosan (CS) to gain mucoadhesive properties. In this context, an innovative nanoparticle formulation that can protect orally administered DCX from GIT conditions and deliver the drug to the intestinal tumoral region by accumulating in mucus has been designed. For this purpose, DCX-PLGA nanoparticles (NPs) and CS/DCX-PLGA NPs were prepared, and their in vitro characteristics were elucidated. Nanoparticles around 250-300 nm were obtained. DCX-PLGA NPs had positive surface charge with CS coating. The formulations have the potential to deliver the encapsulated drug to the bowel according to the in vitro release studies in three different simulated GIT fluids for approximately 72 h. Mucin interaction and penetration into the artificial mucus layer were also investigated in detail, and the mucoadhesive and mucus-penetration characteristics of the formulations were examined. Furthermore, in vitro release kinetic studies of the NPs were elucidated. DCX-PLGA NPs were found to be compatible with the Weibull model, and CS/DCX-PLGA NPs were found to be compatible with the Peppas-Sahlin model. Within the scope of in vitro cytotoxicity studies, the drug-loaded NPs showed significantly higher cytotoxicity than a DCX solution on the HT-29 colon cell line, and CS/DCX-PLGA showed the highest cytotoxicity (p < 0.05). According to the permeability studies on the Caco-2 cell line, the CS/DCX-PLGA formulation increased permeability by 383% compared to free DCX (p < 0.05). In the light of all results, CS/DCX-PLGA NPs can offer a promising and innovative approach as an oral anticancer drug-loaded nanoformulation for intestinal tumors.

Changing paradigms in the treatment of tuberculosis

Tuberculosis, caused by Mycobacterium tuberculosis, is a disease long dealt with, but still remains the second leading cause of death world-wide. The current anti-tubercular chemotherapy primarily targets the microbial pathogenesis, which however, is failing due to the development of drug resistance. Moreover, with fewer new drugs reaching the market, there is a need to focus on alternate treatment approaches that could be used as stand-alone or adjunct therapy and the existing drugs, referred to as Track II chemotherapy. This article is an attempt to review the changing global patterns of tuberculosis and its treatment. Further, newer drug delivery approaches like multi-particulate drug carriers which increase the therapeutic efficacy and bring down the systemic toxicity associated with drugs have also been discussed. There is also a need to use interventions which can be used as Track II therapy. Host-directed therapeutics (HDT) is an emerging area concept in which host cell functions and hence the response to pathogens can be modulated, which can help manage TB. HDT decreases damage induced due to inflammation and necrosis in the lungs and other parts of the body due to the disease. Various immuno-modulatory pathways have been discussed in this review which could be explored further to treat TB. An in-depth understanding of multi-particulate drug carriers and HDT could help in dealing with tuberculosis; however, there is still a long way to go.

Chitosan/poly(lactic-co-glycolic)acid Nanoparticle Formulations with Finely-Tuned Size Distributions for Enhanced Mucoadhesion

Non-parenteral drug delivery systems using biomaterials have advantages over traditional parenteral strategies. For ocular and intranasal delivery, nanoparticulate systems must bind to and permeate through mucosal epithelium and other biological barriers. The incorporation of mucoadhesive and permeation-enhancing biomaterials such as chitosan facilitate this, but tend to increase the size and polydispersity of the nanoparticles, making practical optimization and implementation of mucoadhesive nanoparticle formulations a challenge. In this study, we adjusted key poly(lactic-co-glycolic) acid (PLGA) nanoparticle formulation parameters including the organic solvent and co-solvent, the concentration of polymer in the organic phase, the composition of the aqueous phase, the sonication amplitude, and the inclusion of chitosan in the aqueous phase. By doing so, we prepared four statistically unique size groups of PLGA NPs and equally-sized chitosan-PLGA NP counterparts. We loaded simvastatin, a candidate for novel ocular and intranasal delivery systems, into the nanoparticles to investigate the effects of size and surface modification on drug loading and release, and we quantified size- and surface-dependent changes in mucoadhesion in vitro. These methods and findings will contribute to the advancement of mucoadhesive nanoformulations for ocular and nose-to-brain drug delivery.

Polymeric nano- and microparticulate drug delivery systems for treatment of biofilms

Now-a-days healthcare systems face great challenges with antibiotic resistance and low efficacy of antibiotics when combating pathogenic bacteria and bacterial biofilms. Administration of an antibiotic in its free form is often ineffective due to lack of selectivity to the infectious site and breakdown of the antibiotic before it exerts its effect. Therefore, polymeric delivery systems, where the antibiotic is encapsulated into a formulation, have shown great promise, facilitating a high local drug concentration at the site of infection, a controlled drug release and less drug degradation. All this leads to improved therapeutic effects and fewer systemic side effects together with a lower risk of developing antibiotic resistance. Here, we review and provide a comprehensive overview of polymer-based nano- and microparticles as carriers for antimicrobial agents and their effect on eradicating bacterial biofilms. We have a main focus on polymeric particulates containing poly(lactic-co-glycolic acid), chitosan and polycaprolactone, but also strategies involving combinations of these polymers are included. Different production techniques are reviewed and important parameters for biofilm treatment are discussed such as drug loading capacity, control of drug release, influence of particle size and mobility in biofilms. Additionally, we reflect on other promising future strategies for combating biofilms such as lipid-polymer hybrid particles, enzymatic biofilm degradation, targeted/triggered antibiotic delivery and future alternatives to the conventional particles.

Nanomedicines as Drug Delivery Carriers of Anti-Tubercular Drugs: From Pathogenesis to Infection Control

In spite of advances in tuberculosis (TB) chemotherapy, TB is still airborne deadly disorder as a major issue of health concern worldwide today. Extensive researches have been focused to develop novel drug delivery systems to shorten the lengthy therapy approaches, prevention of relapses, reducing dose-related toxicities and to rectify technologically related drawbacks of anti-tubercular drugs. Moreover, the rapid emergence of drug resistance, poor patient compliance due to negative therapeutic outcomes and intracellular survival of Mycobacterium highlighted to develop carrier with optimum effectiveness of the anti-tubercular drugs. This could be achieved by targeting and concentrating the drug on the infection reservoir of Mycobacterium. In this article, we briefly compiled the general aspects of Mycobacterium pathogenesis, disease treatment along with progressive updates in novel drug delivery carrier system to enhance therapeutic effects of drug and the high level of patient compliance. Recently developed several vaccines might be shortly available as reported by WHO.

Physicochemical and In Vitro Evaluation of Drug Delivery of an Antibacterial Synthetic Benzophenone in Biodegradable PLGA Nanoparticles

Due to the increasing incidents of antimicrobial-resistant pathogens, the development of new antibiotics and their efficient formulation for suitable administration is crucial. Currently, one group of promising antimicrobial compounds are the benzophenone tetra-amides which show good activity even against gram-positive, drug-resistant pathogens. These compounds suffer from poor water solubility and bioavailability. It is therefore important to develop dosage forms which can address this disadvantage while also maintaining efficacy and potentially generating long-term exposures to minimize frequent dosing. Biodegradable nanoparticles provide one solution, and we describe here the encapsulation of the experimental benzophenone-based antibiotic, SV7. Poly-lactic-co-glycolic-acid (PLGA) nanoparticles were optimized for their physicochemical properties, their encapsulation efficiency, sustained drug release as well as antimicrobial activity. The optimized formulation contained particles smaller than 200 nm with a slightly negative zeta potential which released 39% of their drug load over 30 days. This formulation maintains the antibacterial activity of SV7 while minimizing the impact on mammalian cells.

Nanostructured lipid carriers versus solid lipid nanoparticles for the potential treatment of pulmonary hypertension via nebulization

With the non-selective vasodilating action, short half-life and first-pass metabolism of sildenafil (SC), local application in the lung for pulmonary arterial hypertension is of high demand. Although several nanosystems have been lately investigated, nanostructured lipid carriers (NLCs) give promises of potential safety, biodegradability and controlled drug release. In the current study, NLCs comprising either precirol, stearic acid or beeswax as solid lipid in presence of oleic acid as liquid lipid and PVA or poloxamer as emulsifier were prepared. Optimized NLCs (200-268 nm in size) were appraised versus SLNs both in vitro and in vivo. Precirol/PVA-based SLNs and NLCs ensued high entrapment efficiencies (EE > 95%) and controlled release behaviour over 6 h even though NLCs showed higher release profile. Stability studies at 4 °C indicated potential colloidal and entrapment stability over 3 months. Interestingly, NLCs demonstrated efficient nebulization, low interaction with mucin and higher viability of A549 cells (3-fold increase in IC₅₀ relative to SLNs) providing good aptitudes for pulmonary application. In vivo administration of free SC in rats revealed localized intra-alveolar bleeding, presumably related to excessive vasodilatation. Meanwhile, the nanoencapsulated drug confirmed normal lung parenchyma with minimal incidence of bleeding. Inspiring results highlight the potential of sildenafil-laden nanostructured lipid carriers as pulmonary drug delivery system.

Development of Novel Octanoyl Chitosan Nanoparticles for Improved Rifampicin Pulmonary Delivery: Optimization by Factorial Design

A novel hydrophobic chitosan derivative, octanoyl chitosan (OC) with improved organic solubility was synthesized, characterized, and employed for the preparation of rifampicin (Rif) encapsulated nanoparticle formulations for pulmonary delivery. OC was characterized to confirm acyl group substitution and cytotoxicity in A549 epithelial lung cells. OC nanoparticles were produced by the double emulsion solvent evaporation technique without cross-linking and characterized for particle size distribution, morphology, crystallinity, thermal stability, aerosol delivery, and drug release rate. OC was successfully synthesized with substitution degree of 44.05 ± 1.75%, and solubility in a range of organic solvents. Preliminary cytotoxicity studies of OC showed no effect on cell viability over a period of 24 h on A549 cell lines. OC nanoparticles were optimized using a 3² full factorial design. An optimized batch of OC nanoparticles, smooth and spherical in morphology, had mean hydrodynamic diameter of 253 ± 19.06 nm (PDI 0.323 ± 0.059) and entrapment efficiency of 64.86 ± 7.73% for rifampicin. Pulmonary deposition studies in a two-stage impinger following aerosolization of nanoparticles from a jet nebulizer gave a fine particle fraction of 43.27 ± 4.24%. In vitro release studies indicated sustained release (73.14 ± 3.17%) of rifampicin from OC nanoparticles over 72 h, with particles demonstrating physical stability over 2 months. In summary, the results confirmed the suitability of the developed systems for pulmonary delivery of drugs with excellent aerosolization properties and sustained-release characteristics.

Novel technique of insulin loading into porous carriers for oral delivery

The increasing demand for oral macromolecule delivery encouraged the development of microencapsulation technologies to protect such drugs against gastric and enzymatic degradation. However, microencapsulation often requires harsh conditions that may jeopardize their biological activity. Accordingly, many trials attempted to load macromolecules into porous drug carriers to bypass any formulation induced instability. In this study, we prepared chitosan coated porous poly (d, l-lactide-co-glycolide) (PLGA) microparticles (MPs) loaded with insulin using a novel loading technique; double freeze-drying. The results showed a significant increase in drug loading using only 5 mg/ml initial insulin concentration and conveyed a sustained drug release over uncoated MPs. Furthermore, SEM and confocal microscopy confirmed pore blocking and insulin accumulation within the MPs respectively. The oral pharmacodynamic data on rats also proved the preservation of insulin bioactivity after formulation. Finally, the new coating technique proved to be efficient in producing robust layer of chitosan with higher insulin loading while maintaining insulin activity.

Targeted Delivery of GP5 Antigen of PRRSV to M Cells Enhances the Antigen-Specific Systemic and Mucosal Immune Responses

Efficient delivery of antigens through oral immunization is a first and critical step for successful induction of mucosal immunity, which can provide protection against pathogens invading the mucosa. Membranous/microfold cells (M cells) within the mucosa can transcytose internalized antigen without degradation and thus play an important role in initiating antigen-specific mucosal immune responses through inducing secretory IgA production. In this research, we modified poly (D, L-lactide-co-glycolide) (PLGA) nanoparticles (NPs) with Ulex europaeus agglutinin 1 (UEA-1) and successfully prepared an oral vaccine delivery system, UEA-1/PLGA NPs. PLGA NPs were prepared using a standard double emulsion solvent evaporation technique, which can protect the entrapped PRRSV DNA vaccine [pcDNA3.1-SynORF5 (synthetic ORF5)] or subunit vaccine ORF5-encoded glycoprotein (GP5) from exposure to the gastrointestinal (GI) tract and release the plasmids in a controlled manner. With UEA-1 modification, the UEA-1/PLGA NPs can be effectively transported by M-cells. We investigated immune response induced by UEA-1/PLGA-SynORF5 or UEA-1/PLGA-GP5 following inoculation in mice and piglets. Compared with PLGA-SynORF5 or PLGA-GP5 NPs, UEA-1/PLGA-SynORF5, or UEA-1/PLGA-GP5 NPs stimulated significantly increased serum IgG levels and augmented intestinal IgA levels in mice and piglets (P < 0.05). Our findings indicate UEA-1/PLGA NPs can be applied as a promising and universally robust oral vaccine delivery system.

Chemodrug delivery using integrin-targeted PLGA-Chitosan nanoparticle for lung cancer therapy

In this study, we report the efficacy of RGD (arginine-glycine-aspartic acid) peptide-modified polylactic acid-co-glycolic acid (PLGA)-Chitosan nanoparticle (CSNP) for integrin α_vβ₃ receptor targeted paclitaxel (PTX) delivery in lung cancer cells and its impact on normal cells. RGD peptide-modified chitosan was synthesized and then coated onto PTX-PLGA nanoparticles prepared by emulsion-solvent evaporation. PTX-PLGA-CSNP-RGD displayed favorable physicochemical properties for a targeted drug delivery system. The PTX-PLGA-CSNP-RGD system showed increased uptake via integrin receptor mediated endocytosis, triggered enhanced apoptosis, and induced G2/M cell cycle arrest and more overall cytotoxicity than its non-targeted counterpart in cancer cells. PTX-PLGA-CSNP-RGD showed less toxicity in lung fibroblasts than in cancer cells, may be attributed to low drug sensitivity, nevertheless the study invited close attention to their transient overexpression of integrin α_vβ₃ and cautioned against corresponding uptake of toxic drugs, if any at all. Whereas, normal human bronchial epithelial (NHBE) cells with poor integrin α_vβ₃ expression showed negligible toxicity to PTX-PLGA-CSNP-RGD, at equivalent drug concentrations used in cancer cells. Further, the nanoparticle demonstrated its capacity in targeted delivery of Cisplatin (CDDP), a drug having physicochemical properties different to PTX. Taken together, our study demonstrates that PLGA-CSNP-RGD is a promising nanoplatform for integrin targeted chemotherapeutic delivery to lung cancer.

Role of Nitric Oxide-Releasing Chitosan Oligosaccharides on Mucus Viscoelasticity

Nitric oxide (NO)-releasing chitosan oligosaccharides were modified with ester functional groups to examine how the mucoadhesive nature of the scaffold impacts the ability of NO to degrade mucins from human bronchial epithelial cell cultures and clinical sputum samples collected from patients with cystic fibrosis (CF). Agarose gel electrophoresis experiments indicated that the mucoadhesive NO-releasing chitosan oligosaccharides degraded both the purified mucins and sputum, while control scaffolds (without NO release or mucoadhesive ligands) had no effect on mucin structure. Microscopic observations of sputum treated with the mucoadhesive NO-releasing chitosan oligosaccharide confirmed degradation of the mucin and DNA networks. Similarly, the viscosity and elasticity of sputum were reduced upon treatment with the mucoadhesive NO-releasing chitosan, demonstrating the potential utility of these NO-releasing scaffolds as mucolytic agents.

PLGA Microparticles Entrapping Chitosan-Based Nanoparticles for the Ocular Delivery of Ranibizumab

Age-related macular degeneration (AMD) is the leading cause of certified vision loss worldwide. The standard treatment for neovascular AMD involves repeated intravitreal injections of therapeutic proteins directed against vascular endothelial growth factor, such as ranibizumab. Biodegradable polymers, such as poly(lactic-co-glycolic acid) (PLGA), form delivery vehicles which can be used to treat posterior segment eye diseases, but suffer from poor protein loading and release. This work describes a "system-within-system", PLGA microparticles incorporating chitosan-based nanoparticles, for improved loading and sustained intravitreal delivery of ranibizumab. Chitosan-N-acetyl-l-cysteine (CNAC) was synthesized and its synthesis confirmed using FT-IR and (1)H NMR. Chitosan-based nanoparticles composed of CNAC, CNAC/tripolyphosphate (CNAC/TPP), chitosan, chitosan/TPP (chit/TPP), or chit/TPP-hyaluronic acid (chit/TPP-HA) were incorporated in PLGA microparticles using a modified w/o/w double emulsion method. Nanoparticles and final nanoparticles-within-microparticles were characterized for their protein-nanoparticle interaction, size, zeta potential, morphology, protein loading, stability, in vitro release, in vivo antiangiogenic activity, and effects on cell viability. The prepared nanoparticles were 17-350 nm in size and had zeta potentials of -1.4 to +12 mV. Microscopic imaging revealed spherical nanoparticles on the surface of PLGA microparticles for preparations containing chit/TPP, CNAC, and CNAC/TPP. Ranibizumab entrapment efficiency in the preparations varied between 13 and 69% and was highest for the PLGA microparticles containing CNAC nanoparticles. This preparation also showed the slowest release with no initial burst release compared to all other preparations. Incorporation of TPP to this formulation increased the rate of protein release and reduced entrapment efficiency. PLGA microparticles containing chit/TPP-HA showed the fastest and near-complete release of ranibizumab. All of the prepared empty particles showed no effect on cell viability up to a concentration of 12.5 mg/mL. Ranibizumab released from all preparations maintained its structural integrity and in vitro activity. The chit/TPP-HA preparation enhanced antiangiogenic activity and may provide a potential biocompatible platform for enhanced antiangiogenic activity in combination with ranibizumab. In conclusion, the PLGA microparticles containing CNAC nanoparticles showed significantly improved ranibizumab loading and release profile. This novel drug delivery system may have potential for improved intravitreal delivery of therapeutic proteins, thereby reducing the frequency, risk, and cost of burdensome intravitreal injections.

Delivery of antibiotics with polymeric particles

Despite the wide use of antibiotics, bacterial infection is still one of the leading causes of hospitalization and mortality. The clinical failure of antibiotic therapy is linked with low bioavailability, poor penetration to bacterial infection sites, and the side effects of antibiotics, as well as the antibiotic resistance properties of bacteria. Antibiotics encapsulated in nanoparticles or microparticles made up of a biodegradable polymer have shown great potential in replacing the administration of antibiotics in their "free" form. Polymeric particles provide protection to antibiotics against environmental deactivation and alter antibiotic pharmacokinetics and biodistribution. Polymeric particles can overcome tissue and cellular barriers and deliver antibiotics into very dense tissues and inaccessible target cells. Polymeric particles can be modified to target or respond to particular tissues, cells, and even bacteria, and thereby facilitate the selective concentration or release of the antibiotic at infection sites, respectively. Thus, the delivery of antibiotics with polymeric particles augments the level of the bioactive drug at the site of infection while reducing the dosage and the dosing frequency. The end results are improved therapeutic effects as well as decreased "pill burden" and drug side effects in patients. The main objective of this review is to analyze recent advances and current perspectives in the use of polymeric antibiotic delivery systems in the treatment of bacterial infection.

Polymeric nanoparticles for pulmonary protein and DNA delivery

Polymeric nanoparticles (NPs) are promising carriers of biological agents to the lung due to advantages including biocompatibility, ease of surface modification, localized action and reduced systemic toxicity. However, there have been no studies extensively characterizing and comparing the behavior of polymeric NPs for pulmonary protein/DNA delivery both in vitro and in vitro. We screened six polymeric NPs: gelatin, chitosan, alginate, poly(lactic-co-glycolic) acid (PLGA), PLGA-chitosan and PLGA-poly(ethylene glycol) (PEG), for inhalational protein/DNA delivery. All NPs except PLGA-PEG and alginate were <300nm in size with a bi-phasic core compound release profile. Gelatin, PLGA NPs and PLGA-PEG NPs remained stable in deionized water, serum, saline and simulated lung fluid (Gamble's solution) over 5days. PLGA-based NPs and natural polymer NPs exhibited the highest cytocompatibility and dose-dependent in vitro uptake, respectively, by human alveolar type-1 epithelial cells. Based on these profiles, gelatin and PLGA NPs were used to encapsulate plasmid DNA encoding yellow fluorescent protein (YFP) or rhodamine-conjugated erythropoietin (EPO) for inhalational delivery to rats. Following a single inhalation, widespread pulmonary EPO distribution persisted for up to 10days while increasing YFP expression was observed for at least 7days for both NPs. The overall results support both PLGA and gelatin NPs as promising carriers for pulmonary protein/DNA delivery.

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

Objectives 

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.

Methods

Microparticles were obtained by spray drying, and their morphology, size, zeta potential, thermotropic behaviour and nebulisation ability were evaluated.

Key findings 

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.

Conclusions 

Overall, microparticles based on gelatin covalently bound to ISN and containing RFP showed a promising behaviour for pulmonary drug delivery.

Composition influence on pulmonary delivery of rifampicin liposomes

The effects of lipid concentration and composition on the physicochemical properties, aerosol performance and in vitro toxicity activity of several rifampicin-loaded liposomes were investigated. To this purpose, six liposome formulations containing different amounts of soy phosphatidylcholine and hydrogenated soy phosphatidylcholine, with and without cholesterol and oleic acid, were prepared and fully characterized. Uni- or oligo-lamellar, small (~100 nm), negatively charged (~60 mV) vesicles were obtained. Lipid composition affected aerosol delivery features of liposomal rifampicin; in particular, the highest phospholipid concentration led to a better packing of the vesicular bilayers with a consequent higher nebulization stability. The retention of drug in nebulized vesicles (NER%) was higher for oleic acid containing vesicles (55% ± 1.4%) than for the other samples (~47%). A549 cells were used to evaluate intracellular drug uptake and in vitro toxicity activity of rifampicin-loaded liposomes in comparison with the free drug. Cell toxicity was more evident when oleic acid containing liposomes were used.

Synthesis, characterization and in-vitro antitubercular activity of isoniazid-gelatin conjugate

OBJECTIVES

A novel and simple method to synthesize antitubercular-protein conjugate by solid phase synthesis was developed employing a carboxypolystyrene resin. The aim was to covalently bind a drug with antitubercular activity, isoniazid, to a biomacromolecule, gelatin, widely used in the pharmaceutical, cosmetic and food industry.

METHODS

Calorimetric and (1) H NMR analyses were performed to verify the bond formation between the antitubercular drug and gelatin. After absorption isoniazid delivers toxic metabolites and so an oxidation test with tert-butyl hydroperoxide was performed to assess the amount of toxic metabolites released from the prodrug (gelatin linked to isoniazid), compared with isoniazid itself.

KEY FINDINGS

  Spectrophotometric analysis revealed that the protein derivative was an excellent isoniazid prodrug since there was a 40% reduction in release of toxic metabolites (isonicotinic acid) by the prodrug. The results clearly showed that antitubercular moieties, covalently linked to a natural polymer, allowed the introduction of peculiar features for specific pharmaceutical applications into the macromolecule. In addition, antitubercular activity of the new polymer was determined by Middlebrook 7H11 medium against Mycobacterium tuberculosis complex.

CONCLUSIONS

The new isoniazid-gelatin conjugate showed significant antitubercular activity and for this reason should be useful as an efficacious tool in the treatment of tuberculosis.

Nanoscale Particles for Lung Delivery of siRNA

Small interfering RNAs (siRNAs) are potent molecules capable of blocking gene expression after entering cell cytoplasm. Despite their strong efficacy, they need to be carried by nanoscale delivery systems that can protect them against degradation in biological fluids, increase their cellular uptake and favor their subcellular distribution. Several studies have highlighted the potential of local pulmonary delivery of siRNAs for the treatment of lung diseases. For this purpose, nanoscale delivery systems were addressed to target passively or actively the target cell. This review discusses the possibilities of approaching lung delivery of nanoscale particles carrying siRNAs.

Alternatives to conventional suspensions for pulmonary drug delivery by nebulisers: a review

This review discusses the reports of alternative dosage forms to suspension formulations of hydrophobic drugs for nebulisers. Suspensions for nebulisers, although widely used over recent years, have several limitations which have led to pharmaceutical researchers looking for alternative, better performing preparations. Particular attention has been directed towards the use of nanoparticles as carriers of hydrophobic active ingredients. Several nanoformulations have been prepared and compared in vitro and/or in vivo with the corresponding microsuspension formulation. It is also clear that future studies in this field should address the parallel important aspects of safety and economical aspects of nanoparticualte formulations.

Novel microparticle drug delivery systems based on chitosan and Eudragit® RSPM to enhance diltiazem hydrochloride release property

The aim of this study was to enhance the release properties of diltiazem hydrochloride (diltiazem HCl) by using microparticle system. For this reason, microparticle drug delivery systems based on chitosan and Eudragit(®)RSPM were developed. The microparticles were prepared by using double-emulsion solvent extraction method and the mean sizes of microparticles were less than 120 µm. The in vitro drug release from microparticles was studied in simulated gastric (pH 1.2) and intestinal media (pH 7.4) than the results were evaluated by kinetically. In vitro diltiazem HCl release from microparticles showed good zero order kinetic. For the microparticles with chitosan, the release of diltiazem HCl at pH 1.2 could be effectively sustained, while the release of diltiazem HCl increased at pH 7.4 when compared to Eudragit(®)RSPM microparticles. The highest release percent obtained was 1:1 ratio of drug: polymer at pH 1.2 and 7.4. All results clearly suggest that the release properties of diltiazem HCl were improved by using microparticle systems especially which contain chitosan.

Differentiation of bone marrow stromal cells in poly(lactide-co-glycolide)/chitosan scaffolds

This study investigates the physicochemical properties of poly(lactide-co-glycolide) (PLGA)/chitosan scaffolds and the neuron growth factor (NGF)-guided differentiation of bone marrow stromal cells (BMSCs) in the scaffolds. The scaffolds were prepared by the crosslinking of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, N-hydroxysuccinimide and genipin, and the differentiating BMSCs were characterized against CD44, CD90 and NeuN. The scaffold with 20% PLGA yielded 95% porosity, Young's modulus of 13MPa, 70% adhesion of BMSCs and 1.6-fold increase in the cell viability over 7-day cultivation. BMSCs without guidance in the PLGA/chitosan scaffolds were prone to differentiate toward osteoblasts with apparent deposition of calcium. When NGF was introduced, an increased weight percentage of PLGA yielded more identified neurons. In addition, mature neurons emerged from the PLGA-rich biomaterials after induction with NGF over 2 days. A proper control over the physical and biomedical property of the scaffolds and the NGF-guided differentiation of BMSCs can be promising for nerve regeneration.

Surface modification of mitoxantrone-loaded PLGA nanospheres with chitosan

The purpose of this research was to develop polylactic-co-glycolic acid (PLGA) nanospheres surface modified with chitosan (CS). Mitoxantrone- (MTO-) loaded PLGA nanospheres were prepared by a solvent evaporation technique. The PLGA nanospheres surface was modified with CS by two strategies (adsorption and covalent binding). PLGA nanospheres of 248.4+/-21.0 nm in diameter characterized by the laser light scattering technique, scanning electron microscopy (SEM) are spherical and its drug encapsulation efficiency is 84.1+/-3.4%. Zeta potential of unmodified nanospheres was measured to be negative -21.21+/-2.13 mV. The positive zeta potential of modified nanospheres reveals the presence of CS on the surface of the modified nanospheres. Modified nanospheres were characterized for surface chemistry by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FT-IR). FT-IR spectra exhibited peaks at 3420 cm(-1) and 1570 cm(-1), XPS spectra shows the N 1s (atomic orbital 1s of nitrogen) region of the surface of the nanospheres, corresponding to the primary amide of CS. In vitro drug release demonstrated that CS-modified nanospheres have many advantages such as prolonged drug release property and decreased the burst release over the unmodified nanospheres, and the modified nanospheres by covalent binding method could achieve the release kinetics of a relatively constant release. These data demonstrate high potential of CS-modified PLGA nanospheres for the anticancer drug carrier.