Oral administration of amphotericin B nanoparticles: antifungal activity, bioavailability and toxicity in rats

Synergistic Antifungal Effect of Amphotericin B-Loaded Poly(Lactic-Co-Glycolic Acid) Nanoparticles and Ultrasound against Candida albicans Biofilms

Candida albicans is a human opportunistic pathogen that causes superficial and life-threatening infections. An important reason for the failure of current antifungal drugs is related to biofilm formation, mostly associated with implanted medical devices. The present study investigated the synergistic antifungal efficacy of low-frequency and low-intensity ultrasound combined with amphotericin B (AmB)-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (AmB-NPs) against C. albicans biofilms. AmB-NPs were prepared by a double-emulsion method and demonstrated lower toxicity than free AmB. We then established biofilms and treated them with ultrasound and AmB-NPs separately or jointly in vitro and in vivo The results demonstrated that the activity, biomass, and proteinase and phospholipase activities of biofilms were decreased significantly after the combination treatment of AmB-NPs with 42 kHz of ultrasound irradiation at an intensity of 0.30 W/cm² for 15 min compared with the controls, with AmB alone, or with ultrasound treatment alone (P < 0.01). The morphology of the biofilms was altered remarkably after joint treatment based on confocal laser scanning microscopy (CLSM), especially in regard to reduced thickness and loosened structure. Furthermore, the same synergistic effects were found in a subcutaneous catheter biofilm rat model. The number of CFU from the catheter exhibited a significant reduction after joint treatment with AmB-NP and ultrasound for seven continuous days, and CLSM and scanning electron microscopy (SEM) images revealed that the biofilm on the catheter surface was substantially eliminated. This method may provide a new noninvasive, safe, and effective therapy for C. albicans biofilm infection.

Antifungal and Mucoadhesive Properties of an Orally Administered Chitosan-Coated Amphotericin B Nanostructured Lipid Carrier (NLC)

Surface-modified nanostructured lipid carriers (NLC) represent a promising mode of drug delivery used to enhance retention of drugs at absorption site. Formulated chitosan-coated amphotericin-B-loaded NLC (ChiAmp NLC) had a size of 394.4 ± 6.4 nm, encapsulation and loading efficiencies of 86.0 ± 3% and 11.0 ± 0.1% respectively. Amphotericin-B release from NLCs was biphasic with no changes in physical properties upon exposure to simulated gastrointestinal conditions. Antifungal properties of Amphotericin-B and ChiAmpB NLC were comparable but ChiAmpB NLC was twice less toxic to red blood cells and ten times safer on HT-29 cell lines. In vitro mucoadhesion data were observed ex vivo, where ChiAmpB NLC resulted in higher retention within the small intestine compared to the uncoated formulation. The data strongly offers the possibility of orally administering a non-toxic, yet effective Amphotericin-B nanoformulation for the treatment of systemic fungal infections.

The Development of Oral Amphotericin B to Treat Systemic Fungal and Parasitic Infections: Has the Myth Been Finally Realized?

Parenteral amphotericin B has been considered as first-line therapy in the treatment of systemic fungal and parasitic infections, however its use has been associated with a number of limitations including affordability, accessibility, and an array of systemic toxicities. Until very recently, it has been very challenging to develop a bioavailable formulation of amphotericin B due to its physical chemical properties, limited water and lipid solubility, and poor absorption. This perspective reviews several novel oral Amphotericin B formulations under development that are attempting to overcome these limitations.

The preparation and investigation of spinosin–phospholipid complex self-microemulsifying drug delivery system based on the absorption characteristics of spinosin

Objectives

The aim of this research was to investigate the intestinal absorption characteristics and mechanisms of spinosin (SPI), and a new dosage form was prepared to increase the intestinal absorption of SPI.

Methods

In this study, the intestinal absorption characteristics and mechanisms of SPI were first investigated using in situ absorption model and Caco-2 monolayer model. Subsequently, the phospholipid complex (PLC) loaded with SPI was prepared followed by a self-microemulsifying drug delivery system (SMEDDS) technique for developing a more efficient formulation.

Key findings

The results showed that the absorption rate constant (0.02 h−1) and absorption percentage (10%) of SPI were small. Paracellular and active transport pathways mainly mediated the intestinal absorption of SPI. Moreover, SPI-PLC-SMEDDS showed a nanoscale particle size and excellent dispersibility in vitro. The cellular uptake and transportation properties of SPI-PLC-SMEDDS in the Caco-2 cell model were improved significantly. Besides, a statistically dramatically higher oral bioavailability (almost fivefold) was observed following the oral administration of SPI-PLC-SMEDDS than free SPI on the basis of pharmacokinetic experiment results. Furthermore, the SPI-PLC-SMEDDS exhibited certain immunization.

Conclusions

SPI-PLC-SMEDDS could be a promising oral drug delivery system to improve the absorption of SPI.

Solid nanoparticles for oral antimicrobial drug delivery: a review

Most microbial infectious diseases can be treated successfully with the remarkable array of antimicrobials current available; however, antimicrobial resistance, adverse effects, and the high cost of antimicrobials are crucial health challenges worldwide. One of the common efforts in addressing this issue lies in improving the existing antibacterial delivery systems. Solid nanoparticles (SNPs) have been widely used as promising strategies to overcome these challenges. In addition, oral delivery is the most common method of drug administration with high levels of patient acceptance. Formulation into NPs can improve drug stability in the harsh gastrointestinal (GI) tract environment, providing opportunities for targeting specific sites in the GI tract, increasing drug solubility and bioavailability, and providing sustained release in the GI tract. Here, we discuss SNPs for the oral delivery of antimicrobials, including solid lipid NPs (SLNs), polymeric NPs (PNs), mesoporous silica NPs (MSNs) and hybrid NPs (HNs). We also discussed about the role of nanotechnology in IV to oral antimicrobial therapy development as well as challenges, clinical transformation, and limitations of SNPs for oral antimicrobial drug delivery.

Resistance to Nano-Based Antifungals Is Mediated by Biomolecule Coronas

Fungal infections are a growing global health and agricultural threat, and current chemical antifungals may induce various side-effects. Thus, nanoparticles are investigated as potential novel antifungals. We report that nanoparticles' antifungal activity strongly depends on their binding to fungal spores, focusing on the clinically important fungal pathogen Aspergillus fumigatus as well as common plant pathogens, such as Botrytis cinerea. We show that nanoparticle-spore complex formation was enhanced by the small nanoparticle size rather than the material, shape or charge, and could not be prevented by steric surface modifications. Fungal resistance to metal-based nanoparticles, such as ZnO-, Ag-, or CuO-nanoparticles as well as dissolution-resistant quantum dots, was mediated by biomolecule coronas acquired in pathophysiological and ecological environments, including the lung surfactant, plasma or complex organic matters. Mechanistically, dose-dependent corona-mediated resistance occurred via reducing physical adsorption of nanoparticles to fungal spores. The inhibitory effect of biomolecules on the antifungal activity of Ag-nanoparticles was further verified in vivo, using the invertebrate Galleria mellonella as an A. fumigatus infection model. Our results explain why current nanoantifungals often show low activity in realistic application environments, and will guide nanomaterial designs that maximize functionality and safe translatability as potent antifungals for human health, biotechnology, and agriculture.

Antifungal Therapy in Birds: Old Drugs in a New Jacket

The use of antifungals in birds is characterized by interspecies and interindividual variability in the pharmacokinetics, affecting drug safety and efficacy. Oral antifungal drug absorption is a complex process affected by drug formulation characteristics, gastrointestinal anatomy, and physiology. New antifungal drug delivery systems can enhance drug stability, reduce off-target side effects, prolong residence time in the blood, and improve efficacy. Topical administration of antifungals through nebulization shows promising results. However, therapeutic output is highly influenced by drug formulation and type of nebulizer, indicating these factors should be taken into account when selecting this medication route.

Brain-Eating Amoebae: Silver Nanoparticle Conjugation Enhanced Efficacy of Anti-Amoebic Drugs against Naegleria fowleri

The overall aim of this study was to determine whether conjugation with silver nanoparticles enhances effects of available drugs against primary amoebic meningoencephalitis due to Naegleria fowleri. Amphotericin B, Nystatin, and Fluconazole were conjugated with silver nanoparticles, and synthesis was confirmed using UV-visible spectrophotometry. Atomic force microscopy determined their size in range of 20-100 nm. To determine amoebicidal effects, N. fowleri were incubated with drugs-conjugated silver nanoparticles, silver nanoparticles alone, and drugs alone. The findings revealed that silver nanoparticles conjugation significantly enhanced antiamoebic effects of Nystatin and Amphotericin B but not Fluconazole at micromolar concentrations, compared with the drugs alone. For the first time, our findings showed that silver nanoparticle conjugation enhances efficacy of antiamoebic drugs against N. fowleri. Given the rarity of the disease and challenges in developing new drugs, it is hoped that modifying existing drugs to enhance their antiamoebic effects is a useful avenue that holds promise in improving the treatment of brain-eating amoebae infection due to N. fowleri.

Silver nanoparticle conjugation affects antiacanthamoebic activities of amphotericin B, nystatin, and fluconazole

Infectious diseases are the leading cause of morbidity and mortality, killing more than 15 million people worldwide. This is despite our advances in antimicrobial chemotherapy and supportive care. Nanoparticles offer a promising technology to enhance drug efficacy and formation of effective vehicles for drug delivery. Here, we conjugated amphotericin B, nystatin (macrocyclic polyenes), and fluconazole (azole) with silver nanoparticles. Silver-conjugated drugs were synthesized successfully and characterized by ultraviolet-visible spectrophotometry, Fourier transform infrared spectroscopy, and atomic force microscopy. Conjugated and unconjugated drugs were tested against Acanthamoeba castellanii belonging to the T4 genotype using amoebicidal assay and host cell cytotoxicity assay. Viability assays revealed that silver nanoparticles conjugated with amphotericin B (Amp-AgNPs) and nystatin (Nys-AgNPs) exhibited significant antiamoebic properties compared with drugs alone or AgNPs alone (P < 0.05) as determined by Trypan blue exclusion assay. In contrast, conjugation of fluconazole with AgNPs had limited effect on its antiamoebic properties. Notably, AgNP-coated drugs inhibited amoebae-mediated host cell cytotoxicity as determined by measuring lactate dehydrogenase release. Overall, here we present the development of a new formulation of more effective antiamoebic agents based on AgNPs coated with drugs that hold promise for future applications.

Long circulating PEGylated-chitosan nanoparticles of rosuvastatin calcium: Development and in vitro and in vivo evaluations

The aim of this study was to improve the pharmacokinetics and pharmacodynamics profile of rosuvastatin calcium by formulating long-circulating PEGylated chitosan nanoparticles (NPs). Chitosan was PEGylated by a carbodiimide mediated reaction, using a carboxylic acid derivative of PEG (polyethylene glycol). The NPs were optimised for particle size, polydispersity index, zeta potential and drug entrapment efficiency. In vitro drug release, pharmacokinetic and pharmacodynamics studies of the optimized nanoparticles were performed. PEGylation of chitosan was confirmed by FTIR analysis. Drug-excipient compatibility was studied by differential scanning calorimetry and FTIR analyses. Two batches of nanoparticles were optimized with particle size of <200nm and entrapment efficiency of ≈14%. In vitro drug release studies revealed cumulative release of 14.07±0.57% and 22.02±0.81% of rosuvastatin over the period of 120h, indicating appreciable sustained release of drug. TEM analysis showed the spherical structure of nanoparticles. Pharmacokinetic studies indicated that optimized NPs showed prolonged drug release over a period of 72h. Pharmacodynamics studies in hyperlipidemic rat model demonstrated greater lipid-lowering capability of rosuvastatin nanoparticles in comparison with plain rosuvastatin. The nanoparticles demonstrated substantial prolonged delivery of the drug in vivo along with better therapeutic action, which could be potential drug delivery modality for 'statins'.

Development of antifungal therapies using nanomaterials

The number and diversity of chemical structures currently available as antibacterial drugs is much higher compared with the number of active substances in relation to pathogenic fungi. In this review we focus on nanotechnology approaches, which offer promising strategies to create nanoagents that possess broad-spectrum antifungal activity and might overcome mechanisms of antibiotic resistance. Special attention was given to magnetic nanoparticles and their ability to restrict fungal growth directly, which depends on surface chemistry and pathogen strains. We speculate that future developments of new antifungal methods will take advantage of the current knowledge of using of magnetic nanomaterials as anticancer agents based on their ability to induce hyperthermia and enhance photosensitizing processes.