Abstract

Topotecan hydrochloride (TPT) has potential for the treatment of ovarian cancer, but the activity of TPT tends to decrease due to the ring-opening at physiological pH. In this study, we proposed to incorporate TPT liposomes into injectable thermosensitive in situ hydrogel, consisting of chitosan (CS) and β-glycerophosphate (β-GP), for sustained release and preservation of active lactone form of TPT. The rheology studies were carried out to investigate the sol–gel temperature, flow behavior and viscosity of these CS/β-GP systems. The optimized formulation exhibited sol–gel transition at 40.2 ± 0.4 °C, with pseudoplastic flow behavior. The drug release rate of TPT liposomes loaded CS/β-GP hydrogel in phosphate buffer saline (pH = 7.4) was found to be slowed down, and the lactone fraction of TPT in the hydrogel matrix was maintaining 40% after 50 h. In addition, the antitumor efficacy in Kunming mice bearing Hepatoma-22 tumor, after intratumoral injection of TPT liposomes loaded CS/β-GP hydrogel, was higher than that of TPT in saline and TPT in CS/β-GP hydrogel. Those results demonstrated that TPT liposomes loaded CS/β-GP hydrogel could become a potential formulation for improving the antitumor efficacy of TPT and suggested an important technology platform for intratumoral administration of derivative of camptothecin-family drugs.