Amphotericin B loaded albumin microspheres for the treatment of fungal infections.

摘要

Amphotericin B is the first line of drug in the treatment of fungal infections. It is a broad spectrum antifungal agent and the treatment is usually successful with appropriate doses. This drug is highly toxic. Main toxicity is nephrotoxicity, due to its binding with cell lining of afferent arteriole and distal tubule in the kidney. Different approaches have been used to reduce the toxicity by changing the formulations and encapsulating the drug in various types of lipids.;Polymers have been used to encapsulate drugs for slow release and to get the maximum therapeutic effect. The property of albumin as a polymer, that can be used to encapsulate drugs has been recently used. Albumin has the advantage of being nontoxic, biodegradable and practically non immunogenic with in the same species. Albumin microspheres, which are non toxic and biodegradable, have been used for the oral delivery of antibiotics, proteins and other therapeutic agents. The particle size plays an important role in the delivery of drug to the target organs.;Polyethylene glycol 2000 (PEG) has the property of making a brush border of changing configurations and keeping a cloud of water around it. This makes difficult for the immune system to recognize and opsonize by using specific plasma proteins, resulting in avoiding phagocytosis and subsequent clearance from the body. The earlier studies have been done by covalently binding PEG molecule to the drug molecule or by making a block polymer with a hydrophobic end that binds to hydrophobic surfaces and leaving the PEG chain on the open end.;The objective of this study was to develop a platform technology for the preparation of albumin microspheres by crosslinking with glutraldehyde in the presence of PEG by spray drying technique. This will embed the PEG molecules in to the crosslinked matrix.;Various concentrations of PEG were added during the crosslinking of albumin and microspheres were prepared by spray drying method. Physicochemical characterizations for particle size, zeta potential and particle uptake by human microvascular endothelial cell line were performed to evaluate the stealth property of microspheres. Microspheres were analyzed by scanning electron microscopy for cell surface characteristics. New method to estimate the free albumin in crosslinked albumin microspheres was developed to understand the effect of PEG concentration on the crosslinking process.;The second aim was to develop a method to encapsulate the drug amphotericin B in crosslinked albumin matrix and in the crosslinked albumin matrix with PEG. New method for estimation of drug amphotericin B in liquid phase prior to spray drying was developed to see the effect of residual crosslinking agent, if any, on the drug. Physicochemical characterizations of drug containing microspheres were done for particle size, and zeta potential. Method to digest the albumin matrix was standardized and encapsulation efficiency was performed. The dissolution studies were performed to see the release of drug from microspheres. In vitro particle uptake studies were performed in phagocytic cell lines to understand the stealth property conferred by PEG. Drug formulations were tested for in vitro toxicity to human red blood cells. The efficacy study was performed using standard NCCLS method against yeasts to compare the microsphere formulations and solution formulation. The microsphere formulations were studied in vivo in rats for drug kinetics in blood and drug distribution in organs and compared with solution formulation. The hypothesis of longer circulation of particles was also tested in animals by further reducing the particle size of microsphere formulations.