Antitumour efficacy of two paclitaxel formulations for hyperthermic intraperitoneal chemotherapy (HIPEC) in an in vivo rat model.

PURPOSE: To evaluate the tumour growth delay of a peritoneal carcinomatosis (PC) of colorectal origin after intraperitoneal chemotherapy with paclitaxel/randomly-methylated-ß-cyclodextrin (Pac/RAME-ß-CD) versus Taxol® at normo- and hyperthermic conditions in rats. METHODS: Hyperthermic intraperitoneal chemotherapy (HIPEC) was performed 7 days post implantation of the tumour with both formulations at a Pac concentration of 0.24 mg/ml. Tumour evaluation was performed via positron emission tomography (PET) and magnetic resonance imaging (MRI) imaging, measuring tumour activity and tumour volume, respectively. Scans were taken at 2 and 7 days post treatment. RESULTS: PET and MRI data showed a significant reduction in tumour activity and tumour volume for rats treated with Pac/RAME-ß-CD (at normo- and hyperthermic conditions), compared to the control group. Treatment with Taxol® did not result in a significant reduction of tumour activity and tumour volume. No significant differences between the normo- and hyperthermic conditions were observed for both formulations, indicating that hyperthermia and paclitaxel were not synergistic despite the direct cytotoxic effect of hyperthermia. CONCLUSION: Monitoring tumour growth via PET and MRI indicated that Pac/RAME-ß-CD inclusion complexes had a significantly higher efficacy compared to Taxol® in a rat model for peritoneal carcinomatosis.

Sizing nanomatter in biological fluids by fluorescence single particle tracking.

Accurate sizing of nanoparticles in biological media is important for drug delivery and biomedical imaging applications since size directly influences the nanoparticle processing and nanotoxicity in vivo. Using fluorescence single particle tracking we have succeeded for the first time in following the aggregation of drug delivery nanoparticles in real time in undiluted whole blood. We demonstrate that, by using a suitable surface functionalization, nanoparticle aggregation in the blood circulation is prevented to a large extent.

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.