A Novel Inhalable Dry Powder to Trigger Delivery of Voriconazole for Effective Management of Pulmonary Aspergillosis

Invasive pulmonary aspergillosis (IPA) is a fatal fungal infection with a high mortality rate. Voriconazole (VCZ) is considered a first-line therapy for IPA and shows efficacy in patients for whom other antifungal treatments have been unsuccessful. The objective of this study was to develop a high-potency VCZ-loaded liposomal system in the form of a dry-powder inhaler (DPI) using the spray-drying technique to convert liposomes into a nanocomposite microparticle (NCMP) DPI, formulated using a thin-film hydration technique. The physicochemical properties, including size, morphology, entrapment efficiency, and loading efficiency, of the formulated liposomes were evaluated. The NCMPs were then examined to determine their drug content, production yield, and aerodynamic size. The L3NCMP was formulated using a 1:1 lipid/L-leucine ratio and was selected for in vitro studies of cell viability, antifungal activity, and stability. These formulated inhalable particles offer a promising approach to the effective management of IPA.

Beyond the Charge: Interplay of Nanogels' Functional Group and Zeta-Potential for Antifungal Drug Delivery to Human Pathogenic Fungus Aspergillus Fumigatus

The ubiquitous mold Aspergillus fumigatus (A. fumigatus) is one of the main fungal pathogens causing invasive infections in immunocompromised humans. Conventional antifungal agents exhibit limited efficacy and often cause severe side effects. Nanoparticle-based antifungal delivery provides a promising alternative, which can increase local drug concentration; while, mitigating toxicity, thereby enhancing treatment efficacy. Previous research underscores the potential of poly(glycidol)-based nanogels (NG) with negative surface charge as carriers for delivering antifungals to A. fumigatus hyphae. In this study, NG is tailored with 2-carboxyethyl acrylate (CEA) or with phosphoric acid 2-hydroxyethyl acrylate (PHA). It is discovered that quenching with PHA clearly improves the adhesion of NG to hyphal surface and the internalization of NG into the hyphae under protein-rich conditions, surpassing the outcomes of non-quenched and CEA-quenched NG. This enhancement cannot be solely attributed to an increase in negative surface charge but appears to be contingent on the functional group of the quencher. Further, it is demonstrated that itraconazole-loaded, PHA-functionalized nanogels (NGxPHA-ITZ) show lower MIC in vitro and superior therapeutic effect in vivo against A. fumigatus compared to pure itraconazole. This confirms NGxPHA as a promising antifungal delivery system.

Nanotherapeutics for the delivery of antifungal drugs

The treatment of fungal infections is challenging with high death rates reported among immunocompromised patients. The currently available antifungals suffer from poor bioavailability and solubility, pharmacokinetics, and drug resistance, with limited cellular uptake. The clinical pipeline of new antifungals is dry. The incorporation of antifungal drugs into polymer-based nanocarriers to form nanotherapeutics is a promising approach to enhance the therapeutic outcomes of the available antifungal drugs. This review summarizes different polymer-based nanotherapeutics strategies that have been explored for the delivery of antifungals, resulting in enhanced therapeutic outcomes, such as improved pharmacokinetics, targeted/sustained delivery, prolonged drug circulation, retention of the drugs at the localized site of action, and overcoming drug resistance when compared with the free antifungal drugs.

Polymer-based particles against pathogenic fungi: A non-uptake delivery of compounds

The therapy of life-threatening fungal infections is limited and needs urgent improvement. This is in part due to toxic side effects of clinically used antifungal compounds or their limited delivery to fungal structures. Until today, it is a matter of debate how drugs or drug-delivery systems can efficiently reach the intracellular lumen of fungal cells and how this can be improved. Here, we addressed both questions by applying two different polymeric particles for delivery of compounds. Their formulation was based on two biocompatible polymers, i.e., poly(lactic-co-glycolic acid)_50:50 and poly(methyl methacrylate-stat-methacrylic acid)_90:10 yielding particles with hydrodynamic diameters ranging from 100 to 300 nm. The polymers were covalently labeled with the fluorescent dye DY-550 to monitor the interaction between particles and fungi by confocal laser scanning microscopy. Furthermore, the fluorescent dye coumarin-6 and the antifungal drug itraconazole were successfully encapsulated in particles to study the fate of both the cargo and the particle when interacting with the clinically most important human-pathogenic fungi Aspergillus fumigatus, A. terreus, Candida albicans, and Cryptococcus neoformans. While the polymers were exclusively located on the fungal surface, the encapsulated cargo was efficiently transported into fungal hyphae, indicated by increased intracellular fluorescence signals due to coumarin-6. In accordance with this finding, compared to the pristine drug a reduced minimal inhibitory concentration for itraconazole was determined, when it was encapsulated. Together, the herein used polymeric particles were not internalized by pathogenic fungi but were able to efficiently deliver hydrophobic cargos into fungal cells.

Cysteine-phenylalanine-derived self-assembled nanoparticles as glutathione-responsive drug-delivery systems in yeast

Despite the availability of different antifungal drugs in the market, their overall usefulness remains questionable due to the relatively high toxic profiles exerted by them in many cases. In addition, the emergence of drug resistance against these antifungal agents is a matter of concern. Thus, it becomes imperative to explore innovative drug-delivery vehicles to deliver these antifungal drugs for enhanced efficacy, mitigating unwanted side effects and tackling the surge in antifungal resistance. Considering this fact, in this piece of work, we have synthesized stimulus (glutathione)-responsive dipeptide-based self-assembled nanoparticles (NPs) to explore and establish the redox-responsive antifungal drug delivery of a relatively hydrophobic drug, terbinafine (Terb), in Saccharomyces cerevisiae (S. cerevisiae). The NPs were prepared using a relatively aqueous environment as opposed to other Terb formulations that are administered in mostly non-polar solvents and with limited biocompatibility. The NPs demonstrated an encapsulation efficiency of around 99% for Terb and resulted in complete inhibition of yeast-cell growth at a dose of 200 μg mL^-1 of the drug-loaded formulation. Thus, these biocompatible and aqueous dipeptide-based redox-responsive NPs can offer a promising drug-delivery platform to provide enhanced antifungal drug delivery with heightened efficacy and biocompatibility.