Preparation and characterization of an injectable thermosensitive hydrogel for simultaneous delivery of paclitaxel and doxorubicin

In the current study, we aimed to develop a novel injectable thermosensitive hydrogel for simultaneous intra-tumoral administration of paclitaxel (PTX) and doxorubicin hydrochloride (DOX). At first, mixed micelles composed of Pluronic F127 and α-tocopheryl polyethylene glycol 1000 succinate (TPGS) was loaded with PTX and their physicochemical properties including particle size, zeta potential, drug loading content, entrapment efficiency, and the drug release were investigated in details. In the second step, the optimized PTX-loaded micelles prepared in the first step were incorporated into the thermosensitive Pluronic F127/hyaluronic acid (PF127/HA) hydrogel containing fixed amount of DOX. Gel formation temperature, rheological properties, injectability, degradation rates of the hydrogel, and the release rate of PTX and DOX from the hydrogel were examined. The mean particle sizes and zeta potentials of the PTX-loaded micelles were 157.5 ± 20.1 nm and -9.6 ± 1.1 mV, respectively. The entrapment efficiency of the formulation was about 51%. The hydrogel containing PTX-loaded micelles and DOX existed as a solution with low viscosity at 4 °C converted to a semisolid upon increasing the temperature to 35 °C. DOX was completely released from the hydrogel within 12 h, while 40-80% of PTX could be released from the different formulations during 3 days. This novel thermosensitive hydrogel prepared in the current study could be efficiently used for co-delivery of PTX and DOX in solid tumor types.