Improved high-performance liquid chromatographic determination of amphotericin B in human serum and plasma

Engineering Nanogels for Drug Delivery to Pathogenic Fungi Aspergillus fumigatus by Tuning Polymer Amphiphilicity

Invasive aspergillosis is a serious threat to immunodeficient and critically ill patients caused mainly by the fungus Aspergillus fumigatus. Here, poly(glycidol)-based nanogels (NGs) are proposed as delivery vehicles for antifungal agents for sustained drug release. NGs are formed by simple self-assembly of random copolymers, followed by oxidative cross-linking of thiol functionalities. We investigate the impact of copolymer amphiphilicity on NG interaction with mature fungal hyphae in order to select the optimal drug delivery system for model antifungal drug amphotericin B. The results show that drug-loaded NGs decrease minimal inhibitory concentration (MIC) for around four times and slow down the fungal biofilm synthesis at concentrations lower than MIC. Our results suggest that amphiphilicity of nanoparticle's polymer matrix is an important factor in understanding the action of nanocarriers toward fungal cells and should be considered in the development of nanoparticle-based antifungal therapy.

Formulation and characterization of amphotericin B-polyethylenimine-dextran sulfate nanoparticles

A new aqueous nanoparticle system has been developed using complex coacervation employing the oppositely charged polymers polyethylenimine (PEI) and dextran sulfate (DS), with zinc sulfate as a stabilizing agent. Amphotericin B (AmB) was loaded into the nanoparticles as a model drug. The nanoparticles contained PEI and DS in the weight ratio of approximately 1:2. They possessed a zeta potential of approximately +30 mV and demonstrated a narrow size distribution in the range 100-600 nm with a polydispersity index of 0.2. Electron microscopy revealed spherical nanocapsules with a smooth surface. Very favorable drug entrapment and recovery efficiencies of up to 85% were routinely observed. Processing parameters, such as the pH of the PEI solutions, ratio of the two polymers, as well as the concentrations of DS and zinc sulfate, all played a significant role in controlling particle size. Dissolution studies demonstrated a fast release that is dependent on the model drug solubility. The AmB-loaded nanoparticles displayed no toxicity in tissue culture in contrast to free drug and were almost as efficacious as free drug in killing Candida albicans. Advantages of this simple technique are (1) ease of manufacturing and mild preparation conditions, (2) employment of completely aqueous processing conditions, (3) use of biocompatible polymers that can be prepared aseptically, (4) ability to control their size, and (5) a high level of drug entrapment.

Quantitation of Free and Total Amphotericin B in Human Biologic Matrices by a Liquid Chromatography Tandem Mass Spectrometric Method

Amphotericin B remains the standard of care for the treatment of invasive and disseminated fungal infections. Various lipid-based formulations of amphotericin B have been developed to improve its therapeutic index by decreasing toxicity. Previous bioanalytic methods using microbial inhibition or high-pressure liquid chromatography quantified total amphotericin B (free, plasma protein-bound, and lipid-complexed). Sensitivity of this method with a low limit of quantitation of 0.05 microg/mL was inadequate to determine free (unbound) amphotericin B. A sensitive LC/MS/MS method was developed to determine the total amphotericin B value in human plasma and other biologic matrices and the free amphotericin B concentration in plasma. For determination of total plasma amphotericin B concentrations, the sample was diluted and injected onto the LC/MS/MS. For total amphotericin B in other matrices and free amphotericin B in plasma, solid-phase extraction was used. Natamycin served as an internal standard. A PE Sciex API 3000 (Sciex; Concord, Ontario, Canada) was used to assess free amphotericin B in plasma ultrafiltrate determination and an API 3+ for the other matrices, with electrospray interfaced to a C18 analytic column. The low limit of quantitation was 1 ng/mL for ultrafiltrate. For total amphotericin B, the low limits were 2 microg/mL for plasma, 0.05 microg/mL for urine, and 0.4 microg/mL for fecal homogenate. The methods were validated to show the standard range linearity, sensitivity, selectivity, accuracy, precision, and stability of amphotericin B in the matrices tested.