Paclitaxel/beta-cyclodextrin complexes for hyperthermic peritoneal perfusion - formulation and stability.

Due to its low aqueous solubility paclitaxel is currently formulated in a Cremophor EL/ethanol mixture. However, the vehicle of this formulation causes several side-effects. Our objective was to formulate a tensioactive-free and solvent-free paclitaxel solution, which can be used for a hyperthermic intraperitoneal chemoperfusion procedure (HIPEC). The potential of chemically modified beta-cyclodextrins to form complexes with paclitaxel was investigated as a means to increase the aqueous solubility of paclitaxel. Methylated beta-CDs (randomly methylated and 2,6-dimethylated) showed the best ability to solubilise paclitaxel compared to sulfobutyl-ether- and hydroxypropyl-beta-CD. The minimal ratio of paclitaxel versus randomly methylated-beta-cyclodextrin (RAME-beta-CD) yielding 100% inclusion efficiency was 1/20 (mol/mol). Paclitaxel/RAME-beta-CD inclusion complexes prepared via freeze drying were stable for at least 6 months when stored at 4 degrees C. A 5mg/ml paclitaxel solution was formulated using paclitaxel/RAME-beta-CD-complexes. Upon dilution of these solutions, no precipitation was seen. After 24h storage at room temperature or 2h at HIPEC conditions (41.5 degrees C) the 1/40 (mol/mol) ratio showed the highest stability at paclitaxel concentrations of 0.1 and 0.5mg/ml. When hydroxypropyl methylcellulose (HPMC) was added to the reconstitution medium, the stability significantly increased, offering the opportunity to reduce the amount of RAME-beta-CDs in the formulation.