Treatment Of Systemic Fungal Infections Research Articles

SUBA-itraconazole in the treatment of systemic fungal infections.

Conventional itraconazole (c-ITZ) can be used for a variety of fungal infections although variable absorption has been a significant limitation. Super-bioavailable itraconazole (SUBA-ITZ) is a novel formulation that overcomes absorption concerns by utilizing a polymer-matrix to disperse active drug and facilitate dissolution. The pH-driven matrix allows concurrent protonpump inhibitor administration without significant effects on drug concentrations. The enhanced bioavailability of SUBA-ITZ allows for lower dosing, while achieving similar serum concentrations as c-ITZ and SUBA-ITZ is now USFDA approved in the treatment of blastomycosis, histoplasmosisand aspergillosis. Common side effects of SUBA-ITZ include gastrointestinal disorders, peripheral edemaand drug-induced hypertension. Given the significant differences in pharmacokinetics between the formulations, c-ITZ and SUBA-ITZ capsules are not considered interchangeable. It is important to note that drug errors may occur when transitioning a patient from one formulation to another.

A Study on the Effect of Quaternization of Polyene Antibiotics' Structures on Their Activity, Toxicity, and Impact on Membrane Models.

Polyene antibiotics have been used in antifungal therapy since the mid-twentieth century. They are highly valued for their broad spectrum of activity and the rarity of pathogen resistance to their action. However, their use in the treatment of systemic mycoses often results in serious side-effects. Recently, there has been a renewed interest in the development of new antifungal drugs based on polyenes, particularly due to the emergence of highly dangerous pathogenic strains of fungi, such as Candida auris, and the increased incidence of mucormycosis. Considerable understanding has been established regarding the structure-biological activity relationships of polyene antifungals. Yet, no previous studies have examined the effect of introducing quaternized fragments into their molecular structure. In this study, we present a series of amides of amphotericin B, nystatin, and natamycin bearing a quaternized group in the side chain, and discuss their biological properties: antifungal activity, cytotoxicity, and effects on lipid bilayers that mimic fungal and mammalian cell membranes. Our research findings suggest that the nature of the introduced quaternized residue plays a more significant role than merely the introduction of a constant positive charge. Among the tested polyenes, derivatives 4b, 5b, and 6b, which contain a fragment of N-methyl-4-(aminomethyl)pyridinium in their structure, are particularly noteworthy due to their biological activity.

Pharmacokinetics of amphotericin B after accidental overdose in an adult critically ill patient treated with plasmapheresis: a case report and review of literature

Amphotericin B is a broad-spectrum antifungal agent that is used in the treatment of systemic fungal infections. We describe the case of a 62-year-old female patient with recent aneurysmal subarachnoid hemorrhage who was treated for suspected ventriculitis and a fungal coinfection. Instead of liposomal amphotericin B (L-AmB), 465 mg (5 mg/kg) amphotericin B deoxycholate (DOC) was inadvertently administered, leading to refractory shock with multiple organ failure and requiring mechanical ventilation. Since an overdose of amphotericin B can lead to fatal consequences and has a half-life of 15 days, plasmapheresis was started. The serum concentration decreased from 1.32 µg/mL to 0.62 µg/mL before plasmapheresis, demonstrating a mean half-life of 49 hours. After two plasmapheresis sessions, the serum concentration further dropped to 0.26 µg/mL, demonstrating a mean half-life of 17 hours. In contrast, the third plasmapheresis session had no effect on serum concentration. The patient made a full recovery, potentially facilitated by enhanced amphotericin B elimination through plasmapheresis. Positive outcomes were previously reported in two adult patients treated with plasmapheresis. However, other reports without plasmapheresis described fatal outcomes in adult patients, albeit with a twofold overdose compared to the two patients successfully treated with plasmapheresis. Moreover, plasmapheresis itself carries risks such as hypocalcemia, metabolic alkalosis, and coagulation deficits. Consequently, the role of plasmapheresis in amphotericin B overdose is still debated.

Formulation and Development of Hyaluronic Acid based Gel with Ketoconazole-Loaded Nanostructured Lipid Carriers in Fungal Infection.

Ketoconazole is an imidazole ring containing antifungal agent used in the treatment of systemic fungal infections. It acts by blocking the synthesis of ergosterol, an essential component of the fungal cell membrane. The purpose of this work is to construct skin targeting ketoconazole nanostructured lipid carriers (NLCs) loaded hyaluronic acid (HA) modified gel to minimize side effects and provide a controlled release. The NLCs were prepared using emulsion sonication method and their optimized batches were characterized for X-ray diffraction, scanning electron microscopy and fourier transform infrared spectroscopy study. These batches were then incorporated into HA containing gel for convenient application. The final formulation was compared with the marketed formulation for studying its antifungal activity and drug diffusion. Ketoconazole NLCs loaded hyaluronic acid formulation was successfully developed with desirable formulation parameters by using 23 Factorial design. In vitro release study of developed formulation showed prolonged drug release (up to 5 hrs) while ex vivo drug diffusion study on human cadaver skin showed better drug diffusion as compared with marketed formulation. Moreover, the release study and diffusion study results reflected the improvement of antifungal activity of the developed formulation against Candida albicans. The work suggests that ketoconazole NLCs loaded HA modified gel provides prolonged release. The formulation also has good drug diffusion and antifungal activity and thus can act as a promising carrier for topical delivery of ketoconazole.

The Custom R Group Enumeration with Various R Group Libraries at Designated Sites on Amphotericin B.

Amphotericin B is a gold-standard drug, particularly for the treatment of systemic fungal infections. However, its low solubility and permeability limit its application. To improve its bioavailability, AmB may be conjugated with various water-soluble auxiliary groups. Custom R group Enumeration was used at the designated sites of Amphotericin B. The designated sites taken into consideration are the carboxyl moiety of the aglycone part and the amine moiety of the glycone part of Amphotericin B for Enumeration purposes. The enumerated molecules were subjected to QikProp properties. We identified fourteen hits with improved predicted aqueous solubility and cell permeability. Enumeration might be applicable in improving bioavailability, which could lead to the oral formulation of the Amphotericin B drug.

Antifungal drugs

Fungal infections continue to emerge as an important cause of infectious disease and mortality in humans. Amphotericin B deoxycholate (ABD), was the first antifungal that was discovered, and it was released in 1958, and flucytosine, which was developed later and is effective against Candida and Cryptococcus, was introduced in 1978. The discovery of first-generation azoles (fluconazole and itraconazole) in the 1990s has created a new step in the treatment of fungi. In the years that followed, with the development of lipid formulations of amphotericin B, the introduction of second-generation azoles, and the release of the most recently developed class, echinocandins, the foundations of today’s existing antifungal classes were laid. This article is aimed to review the mechanism of action, side effects and clinical use indications of the main antifungal drugs used in the treatment of systemic fungal infections.

Exploration of the binding of antifungal drugs to human P450 2C9 based on docking and molecular dynamics simulation

AbstractAzole compounds, commonly used antifungal agents for the treatment of systemic fungal infections, have been confirmed to show inhibition to some P450 enzymes. However, the potential inhibition or interaction mechanism is elusive. Here, the detailed interaction between first‐generation antifungal agents (miconazole, and its derivatives fluconazole and voriconazole) and CYP2C9 are studied using docking and molecular dynamics (MD) simulation methods. Docking results show that azoles are mainly located in the cavity formed by helices A, F, I, and heme group. MD results indicate flu‐1 and vor‐2 undergo large conformational changes mediated by inter/intramolecular hydrogen bonds (H‐bonds), while other azole conformations exhibit low flexibility in the active site. Interestingly, one water (W7255) joins the interaction between flu‐1 and N204, implying the significance of water in regulating the binding of fluconazole. MM‐GBSA analysis manifests that miconazole possesses highest binding affinity compared to fluconazole and voriconazole, which agrees well with previous reports. Moreover, the per‐residue decomposition suggests that the favorable interactions are dominated by ΔGvdW and ΔGnonpl between azoles and residues (V113/F114, I205/L208, A297/E300/T301, F476/A477) and ΔGvdW should be further ascribed to CH⋯Cl, CH⋯N, CH⋯O and CH⋯π interactions.

Antibiotic-sterol interactions provide insight into the selectivity of natural aromatic analogues of amphotericin B and their photoisomers

Aromatic heptaene macrolides (AHMs) belong to the group of polyene macrolide antifungal antibiotics. Members of this group were the first to be used in the treatment of systemic fungal infections. Amphotericin B (AmB), a non-aromatic representative of heptaene macrolides, is of significant clinical importance in the treatment of internal mycoses. It includes the all-trans heptaene chromophore, whereas the native AHMs contain two cis-type (Z) double bonds within the chromophore system. Lately we have proven that it is possible to obtain AHMs’ stable derivatives in the form of all-trans (AmB-type) isomers by photochemical isomerization. Our further studies have shown that such alteration leads to the improvement of their selective toxicity in vitro. Computational experiments carried out so far were only an initial contribution in the investigation of the molecular basis of the mechanism of action of AHMs and did not provide explanation to observed differences in biological activity between the native (cis-trans) and isomeric (all-trans) AHMs. Herein, we presented the results of two-dimensional metadynamics studies upon AmB and its aromatic analogues (AHMs), regarding preferable binary antibiotic/sterol complexes orientation, as well as more detailed research on the behaviour of AHMs’ alkyl-aromatic side chain in cholesterol- or ergosterol-enriched lipid bilayers.

Clinical Challenges of Emerging and Re-Emerging Yeast Infections in the Context of the COVID-19 Pandemic.

During the geological eras, some fungi, through adaptation and/or environmental/ecological pressure, interacted directly and indirectly with humans, through occasionally harmful interaction interdependent on the individual's immunological condition. Infections caused by yeasts are underreported, subjugated, and underdiagnosed, and treatment is restricted to a few drugs, even after the significant progress of medicine and pharmacology. In the last centuries, antagonistically, there has been an exponential increase of immunocompromised individuals due to the use of immunosuppressive drugs such as corticosteroids, increased cases of transplants, chemotherapeutics, autoimmune diseases, neoplasms, and, more recently, coronavirus disease 2019 (COVID-19). This review aims to survey emerging and re-emerging yeast infections in the current clinical context. Currently, there is an immense clinical challenge for the rapid and correct diagnosis and treatment of systemic mycoses caused by yeasts due to the terrible increase in cases in the current context of COVID-19.

Azole Resistance in Candida Yeasts

Systemic fungal diseases and antifungal resistance represent a serious problem in human medicine and contribute to increased patient mortality. The most common causes of these diseases are opportunistic yeasts of the genus Candida. C. albicans is considered to be the main pathogen, together with C. glabrata, C. tropicalis, C. parapsilosis, and C. krusei. Azole antifungals predominate in the treatment of the systemic mycoses. For antifungal resistance in Candida spp. some genes and their mutations are responsible, the genes ERG11, CDR1, CDR2 and MDR1 being considered the most important. The main target of azole antifungals is the process of ergosterol synthesis. Due to ergosterol crucial functions and its unique structural properties, the synthesis of ergosterol and its individual steps represent the target of most clinically available antifungals. The biofilm appears to be a significant virulence factor of the yeast Candida spp. It allows hematogenous dissemination of cells, prevents the effect of antifungals on all cells during treatment and leads to a high level of antimicrobial resistance. The antifungal resistance in candidiasis often has a multifactorial origin, which must be considered in the treatment of systemic mycoses and in the development of new antifungals.

Preparation, physicochemical characterization, and In vivo evaluation of miconazole nitrate nanosponges for the treatment of systemic mycoses

Miconazole is a Biopharmaceutics Classification System (BCS) class II drug, thus limiting its oral bioavailability. Nanosponges can improve the oral bioavailability of poorly soluble drugs and sustain their release. The work was aimed at formulating miconazole nanosponges to enhance its solubility and consequently, oral bioavailability. Batches of nanosponges incorporating different concentrations (1, 2 and 3 %) of miconazole nitrate were formed using ethyl cellulose (EC), polyvinyl alcohol (PVA), ethanol and Kolliphor® 188. They were characterized using percentage yield, encapsulation efficiency, Differential Scanning Calorimetry (DSC), Xray Diffraction (XRD), particle sizes, polydispersity index (PDI) and Scanning Electron Microscopy (SEM). In vitro antifungal evaluation against Candida albicans was assessed while in vitro release using simulated gastric fluid was done. Furthermore, in vivo release studies in rats were carried out using the bioassay method. The percentage yield of the nanosponges were between 50 to 60 %. Encapsulation efficiencies ranged between 77 and 98 %. Particle sizes ranged between 266.5 and 781.1 nm. Particles were porous and spongy in appearance. Antifungal evaluation of the nanosponges against Candida albicans revealed activity like that of the pure drug. In vitro release studies showed a sustained release pattern for the nanosponges up till 12 hours whereas the unformulated drug peaked at 2 h. In vivo evaluation showed a concentration dependent increase in blood concentration of the drug with NS4 having the highest release. Nanosponges containing miconazole nitrate were successfully formulated and evaluated and are a promising oral delivery system for miconazole nitrate.

Pharmaceutical co-crystals of posaconazole for improvement of physicochemical properties

Posaconazole exerts an extended spectrum of antifungal activity against various strains of clinically relevant moulds and yeasts. In recent years, antifungal triazole posaconazole has become increasingly important for the prophylaxis and treatment of systemic mycoses. After oral administration of posaconazole, absolute bioavailability has been estimated to range from 8% to 47%. Pharmaceutical co-crystallization is a promising approach for improving dissolution rate or manipulating other physical properties of API. The objective of this study is to improve the dissolution rate of posaconazole by co-crystallization. A 1:1 stoichiometric co-crystals of adipic acid were prepared by solvent assisted grinding method. The prepared co-crystals were subjected to solid-state characterization by FTIR, PXRD and DSC studies. The physicochemical properties of posaconazole and co-crystals were assessed in terms of melting point, flowability and dissolution rate. The results indicated improvement in flow property and dissolution rate. In vitro dissolution profile of co-crystals showed a significant increased dissolution of posaconazole from initial period in 0.1 N hydrochloric acid solution. The dissolution efficiency for posaconazole-adipic acid co-crystal was 61.65 % against posaconazole, 46.58 %. Thus, co-crystallization can be a promising approach to prepare posaconazole-adipic acid co-crystals with improved physicochemical properties.

Development of a stability-indicating assay method by HPLC-DAD and MS characterization of forced degradation products of ravuconazole.

Ravuconazole (RAV) is a triazole antifungal with broad spectrum and a novel alternative in the treatment of systemic fungal infections. A stability-indicating method by high-performance liquid chromatography-diode array detection was developed and fully validated to assay ravuconazole in the presence of its degradation products. Separation was achieved with a Sunfire C18 column (250 mm × 4.6 mm id, 5 μm), mobile phase composed of acetonitrile and water (80:20), at 1 mL/min. The volume of injection was 5 μL and DAD detection was performed at 287 nm. RAV was well resolved from its degradation products and the method proved to be linear, selective, accurate, precise and robust. A forced degradation study was conducted on the pure drug under oxidative conditions in presence of H2O2 and metallic ions and under acid, alkaline and neutral hydrolysis. RAV was degraded mainly under alkaline hydrolysis, forming two main degradation products. The chemical structures were proposed according to the data obtained by liquid chromatography coupled to mass spectrometry (LC-MS) analysis. This study provided a new and selective stability-indicating method to evaluate the intrinsic stability of ravuconazole in active pharmaceutical ingredients. The developed method was found to be suitable for quality control routine analysis and to stability studies of ravuconazole.

Influence of ascorbic acid and α-tocopherol on the autoxidation and in vitro antifungal activity of amphotericin B.

Background and Purpose: Amphotericin B (AmB) is the standard treatment for systemic fungal infections; however, the formation of reactive oxygen species reduces the efficacy and stability of this molecule. The present study aimed to evaluate the effect of the combination of AmB with ascorbic acid and α-tocopherol on its autoxidation and antifungal activity.Materials and Methods: The antifungal activity against Candida albicans was evaluated by the viable cell counting method and checking their morphological changes with a scanning electron microscope. Monomer state of AmB was assessed by scanning the UV absorbance in the range of 300-450 nm and the lipid peroxidation was measured using quantification of thiobarbituric acid reactive-substances (TBARS).Results: Based on the findings, the addition of ascorbic acid (3×102 µg/mL) and α-tocopherol (16 µg/mL) to the reaction medium of AmB increased its antifungal activity while maintaining its molecular stability. Moreover, the level of TBARS formed in the reaction medium of AmB was significantly reduced after combination with ascorbic acid and α-tocopherol.Conclusion: Given their availability, their anti-free radical activity, and their low toxicity, the incorporation of ascorbic acid and α-tocopherol into the reaction medium of AmB seems to be a promising approach to obtain an effective antifungal formulation.

Mangiferin enhances the antifungal activities of caspofungin by destroying polyamine accumulation

ABSTRACT The incidence of fungal infections has increased continuously in recent years. Caspofungin (CAS) is one of the first-line drugs for the treatment of systemic fungal infection. However, the emerging CAS-resistant clinical isolates and high economic cost for CAS administration hamper the wide application of this drug. Thus, the combined administration of CAS with other compounds that can enhance the antifungal activity and reduce the dose of CAS has gained more and more attention. In this study, we investigated the effect of mangiferin (MG) on the antifungal activities of CAS. Our results showed that MG acted synergistically with CAS against various Candida spp., including CAS-resistant C. albicans. Moreover, MG could enhance the activity of CAS against biofilm. The in vivo synergism of MG and CAS was further confirmed in a mouse model of disseminated candidiasis. To explore the mechanisms, we found that SPE1-mediated polyamine biosynthesis pathway was involved in the fungal cell stress to caspofungin. Treatment of CAS alone could stimulate SPE1 expression and accumulation of polyamines, while combined treatment of MG and CAS inhibited SPE1 expression and destroyed polyamine accumulation, which might contribute to increased oxidative damage and cell death. These results provided a promising strategy for high efficient antifungal therapies and revealed novel mechanisms for CAS resistance.

Amphotericin B, the Wonder of Today’s Pharmacology Science: Persisting Usage for More Than Seven Decades

Background: Despite several available topical and systemic antifungal drugs for the treatment of fungal infections, Amphotericin B (AmB) is still one of the most common first-line choices in treating systemic fungal infection for more than seven decades after its discovery. 
 Objectives: Amphotericin B which belongs to the polyene group has a wide spectrum of in vitro and in vivo antifungal activity. Its mechanism of antifungal action is characterized by creating a pore in the fungal plasma membrane leading to cell death.
 Methods: In addition to the old formula of deoxycholate-Amphotericin B (D-AmB), three lipid formulas have been developed to reduce the adverse effects of conventional AmB (D-AmB) in the human body and increase its therapeutic efficacy. All of the known available formulas of AmB are administrated via intravenous injection to treat severe systemic fungal infections, while the development of the topical formula of AmB is still under preliminary research. Numerous pharmaceutical formulas of systemic and topical applications with clinical uses of AmB in just humans, not in vitro or animals model, against various fungal infections are discussed in this review. Topical AmB formulas are a promising way to develop effective management and to reduce the adverse effects of intravenous formulas of AmB without laboratory monitoring.
 Results: The wonderful pharmacological properties of AmB with its prolonged use for about seven decades may help researchers to apply its unique features on other various antimicrobial agents by more understanding about the AmB mechanisms of actions.
 Conclusion: Amphotericin B is widely used intravenously for the treatment of systemic fungal infection, while the topical formula of AmB is still under experimental study.

Therapies and Vaccines Based on Nanoparticles for the Treatment of Systemic Fungal Infections

Treatment modalities for systemic mycoses are still limited. Currently, the main antifungal therapeutics include polyenes, azoles, and echinocandins. However, even in the setting of appropriate administration of antifungals, mortality rates remain unacceptably high. Moreover, antifungal therapy is expensive, treatment periods can range from weeks to years, and toxicity is also a serious concern. In recent years, the increased number of immunocompromised individuals has contributed to the high global incidence of systemic fungal infections. Given the high morbidity and mortality rates, the complexity of treatment strategies, drug toxicity, and the worldwide burden of disease, there is a need for new and efficient therapeutic means to combat invasive mycoses. One promising avenue that is actively being pursued is nanotechnology, to develop new antifungal therapies and efficient vaccines, since it allows for a targeted delivery of drugs and antigens, which can reduce toxicity and treatment costs. The goal of this review is to discuss studies using nanoparticles to develop new therapeutic options, including vaccination methods, to combat systemic mycoses caused by Candida sp., Cryptococcus sp., Paracoccidioides sp., Histoplasma sp., Coccidioides sp., and Aspergillus sp., in addition to providing important information on the use of different types of nanoparticles, nanocarriers and their corresponding mechanisms of action.

A Quantitative LC-MS/MS Method for Determination of Liposomal Amphotericin B in Rat Plasma and Tissues and its Application to a Toxicokinetic and Tissue Distribution Study

Background:: Among the existing antifungal drugs, Amphotericin B is the first drug in the treatment of systemic fungal infections. However, its large adverse reactions limit the clinical application and Liposome Amphotericin B resolves the problem. Objective:: In the present study, a rapid, simple, sensitive and efficient method based on LCMS/ MS for determination of liposomal Amphotericin B in rat plasma and tissue samples using natamycin as the internal standard has been developed and validated. Methods: The analytical samples contain the plasma and various tissues disposed of by protein precipitation and determination of liposomal Amphotericin B by an LC-MS/MS. Chromatographic separation was achieved on a Poroshell 120 EC-C18 column (4.6 mm × 50 mm, 2.7 μm) with 10 mmol/L ammonium acetate in water-acetonitrile by gradient elution at a flow rate of 0.7 mL/min. The MS analysis was conducted in positive electrospray ionization with Multiple Reaction Monitoring (MRM). Results:: The calibration curves of plasma and tissues showed good linear range from 50 to 10000 ng/mL. The analytical samples containing plasma and tissues were stable under different storage conditions and temperature. Conclusions: : The developed LC-MS/MS method has been successfully applied to the studies of toxicokinetics and tissue distribution after intravenous injection of liposomal Amphotericin B to rats.

Development of effective AmB/AmB–αCD complex double loaded liposomes using a factorial design for systemic fungal infection treatment

Amphotericin B (AmB) is a very potent antibiotic which still remains as the gold standard for the treatment of systemic fungal infections. AmB is a member of Biopharmaceutical Classification System Class IV, mainly characterized by its poor solubility and low permeability. In this study, AmB/AmB-α cyclodextrin complex double loaded liposomes (DLLs) were developed using the design of experiments (DoE®) approach to optimize/determine the effects of lipid composition and other parameters on final product properties such as encapsulation efficacy, particle size, polydispersity index, and zeta potential. Experimental design 24 was used for optimization of these properties in which four factors were studied in two levels. DLLs showed much higher physical stability than liposomes loaded only with free AmB by the means of particle size, zeta potential and encapsulation efficiency, in addition exhibited sustained release of AmB over 72 h (26.7%) with faster onset time. On the other hand, fourfold improved antimicrobial efficiency, minimum inhibitory concentration (0.125 µg/ml), and minimum fungicidal concentration (0.5 µg/ml) was determined by DLLs against C. albicans compared to Ambisome®. Dose dependent effects of the DLLs were investigated by cytotoxicity studies on Vero and L-929 cells. No significant cytotoxicity observed for AmB/AmB–αCD complex DLLs and Ambisome at tested concentrations while free AmB caused severe cytotoxicity. Lastly the developed DLLs did not cause an increase in NGAL (an early biomarker for acute kidney toxicity) levels for both Vero and HK-2 cell lines compared to free AmB.

Synergistic and antagonistic drug interactions in the treatment of systemic fungal infections

Invasive fungal infections cause 1.6 million deaths annually, primarily in immunocompromised individuals. Mortality rates are as high as 90% due to limited treatments. The azole class antifungal, fluconazole, is widely available and has multi-species activity but only inhibits growth instead of killing fungal cells, necessitating long treatments. To improve treatment, we used our novel high-throughput method, the overlap2 method (O2M) to identify drugs that interact with fluconazole, either increasing or decreasing efficacy. We identified 40 molecules that act synergistically (amplify activity) and 19 molecules that act antagonistically (decrease efficacy) when combined with fluconazole. We found that critical frontline beta-lactam antibiotics antagonize fluconazole activity. A promising fluconazole-synergizing anticholinergic drug, dicyclomine, increases fungal cell permeability and inhibits nutrient intake when combined with fluconazole. In vivo, this combination doubled the time-to-endpoint of mice with Cryptococcus neoformans meningitis. Thus, our ability to rapidly identify synergistic and antagonistic drug interactions can potentially alter the patient outcomes.