In order to examine the efficacy of paclitaxel (Taxol®, Bristol-Myers Squibb) after administration locally at the tumor site, we have developed a thermo-reversible gelling formulation in poloxamer 407 (Pluronic® F-127) solution. Paclitaxel was incorporated in poloxamer 407 [20% (w/w)] at 0.5- and 1.0-mg/mL concentrations. The in vitro release studies were carried out in phosphate-buffered saline (pH 7.4) at 37°C. Control and paclitaxel-poloxamer 407 formulations were administered intratumorally at a dose of 20 mg/kg in B16F1 melanoma-bearing mice. The change in tumor volume as a function of time and the survival of treated animals were used as measures of efficacy. Poloxamer 407 solution undergoes a reversible sol-gel transition when the temperature is raised to above 21°C. In vitro paclitaxel release from poloxamer 407 gels was very slow (only 6.1% after 6 hr) probably due to the poor aqueous solubility of the drug. Significant enhancement in the anti-tumor efficacy was noted following intratumoral administration of paclitaxel-poloxamer 407 formulation. The initial tumor growth rate was delayed by 67% and the tumor volume doubling time was increased by 72% relative to saline control. In addition, more than 91% of the tumor-bearing animals that received paclitaxel in poloxamer 407 gel survived on day 15 post-administration as compared to 58% in the control group. The results of this study show significant benefit of paclitaxel for solid tumor when administered locally in an in situ gelling poloxamer 407 formulation.
Amiji, M. M., Lai, P-K., Shenoy, D. B., & Rao, M. (2002). Intratumoral administration of paclitaxel in an in situ gelling poloxamer 407 formulation. Pharmaceutical Development and Technology, 7(2), 195-202. https://doi.org/10.1081/PDT-120003487