This work evaluated the potential of Pluronics (varieties F127 and P123) in combination with solubilizing agents to be used as syringeable in situ gelling depots of intratumoral β-lapachone (βLAP). Pluronic dispersions prepared at various concentrations in the absence and the presence of ethanol and randomly methylated β-cyclodextrin (RMβCD) were characterized regarding their rheological properties, drug solubilization capacity, and in vitro release. Pluronic F127 (18-23%) formulations combined high ability to solubilize βLAP (enhancement solubility factor up to 50), adequate gel temperature range (over 25 °C), and gel strength at 37 °C enough to guarantee the permanence of the formulation in the administration site for a period of time. βLAP release rate was finely tuned by the concentration of the polymer and the addition of RMβCD (diffusion coefficient ranging between 9 and 69 μg · cm(-2)). The ethanol increases βLAP release rate but simultaneously led to weak gels. This paper shows that βLAP formulations involving temperature-reversible Pluronic gels may be suitable for intratumoral drug delivery purposes.
