Development of amphotericin B loaded polymersomes based on (PEG)3-PLA co-polymers: Factors affecting size and in vitro evaluation

Amphotericin B (AmB) is a broad spectrum antifungal and antileishmenial agent and its clinical use is limited due to substantial dose limiting toxicities such as nephrotoxicity. In this work, amphotericin B is formulated in polymersomes of branched (PEG)3-PLA co-polymer. Polymersomes were prepared by solvent injection method and the effects of various formulation and process parameters on size and size distribution were studied. The results showed that viscosity of biphasic solution during formulation has significant influence on the size and size distribution of the polymersomes. Further, drug-loaded polymersomes with size of 199.6 ± 14.1 nm, PDI of 0.258 ± 0.18, zeta potential (ζ) of −18.07 ± 4.91 mV and loading of 16.26 ± 2.50% were obtained. Drug was found to be intercalated in the wall of polymersomes as observed using FITC tagged drug and CLSM study. An in vitro release media containing sodium deoxycholate was developed and a significant amount of drug release was observed up to 24 h there after a very slow release was obtained. Free drug was not found in the formulation and different molecular forms of the drug (AmB) were observed by UV–visible spectroscopy and circular dichroism. This was further supported by hemolysis experiments, where negligible hemolysis in the test formulation was observed as compared to 100% hemolysis in a marketed formulation (Fungizone).