Exploration of the cardinal formulation parameters influencing the encapsulation and physicochemical properties of co-loaded anticancer dual drug nanoliposomes

Abstract

Rationale-based modulation of physico-chemical properties is critical towards design of optimal liposomal formulations having desired pharmacokinetic and pharmacodynamic profiles. The aim of the study was evaluation of critical formulation factors which may influence the encapsulation efficiency, hydrodynamic diameter, electrokinetic potential, internal morphology and drug release profiles of nanoliposomes. Doxorubicin and Vincristine were actively co-loaded in preformed PEGylated liposomes prepared using ethanolic injection. The variation of independent factors (transmembrane gradient, lipid-molar ratio, drug loading temperature, phosphatidylcholine chain length, sequence of drug addition, drug loading pH, external medium) on dependent variables were evaluated using array of univariate analysis with key determinants further analysed using multivariate studies. Univariate study results showed that concentration of ammonium sulphate, drug loading pH and lipid-molar ratio had significant effect on dependent variables. Nanoliposomes prepared in multivariate studies exhibited high encapsulation efficiency (>95%), particle size (Z-average: 106.55 ± 6.63 nm) and surface charge of −5.55 ± 2.77 mV. The optimized nanoliposomes exhibited characteristic coffee-bean shaped morphology showing doxorubicin nanoprecipitation and electron dense vincristine presence in internal aqueous phase that exhibited controlled in-vitro release of both drugs unaffected by presence of each other. Further, an attempt was made to correlate these results to the chemical structure and physicochemical properties of the drugs.