Nanovectors for targeted chemotherapy in cervical cancer
Cervical Intraepithelial Neoplasia (CIN) or Human Papilloma Virus (HPV) is known as the precancerous stages of cervical cancer and may be treated with antineoplastic agents Current treatment includes intravenous administration of Gemcitabine and 5-Fluorouracil however, these drugs have an undesirable side effect profile. This may be overcome by local administration of chemotherapeutic drugs to the site of the cancer. The purpose of this study was to design a drug delivery system that can be locally administered to the site of the cervical cancer and possess thermosonic properties. Designs of three Thermosonic Injectable Organogels (TIO’s) were undertaken using ring opening polymerization (open ring reaction) to formulate three different gels to test the response ability of the gels against thermal and ultrasound exposure. The times taken for these gels to form were recorded at below 15 minutes. All three TIO’s responded differently to thermal and ultrasound stimuli. Physical changes in the gels were noted and further studies were undertaken to confirm their responsiveness towards the dual-stimuli. All three TIO’s showed a dense microstructure containing pores catering for the incorporation of drugs or drug-loaded carriers. Rheological studies showed that there was an increase in viscosity of the gels under increasing heat even though the response differed between TIO formulations. The gels were non-cytotoxic at distinct concentrations ranging between 6.1mg/ml-7.8mg/ml. Solid Lipid Nanospheres (SLN’s) were then designed which encapsulated the mode antineoplastic drug 5-Fluorouracil. The SLN’s were spherical in shape and had an acceptable poly dispersion index (PDI) which was below 0.7 after ultrasonication and filtration of prepared samples. The SLN’s were then incorporated by direct additition and dispersion into the TIO formulations before undertaking the open ring reaction to form Thermosonic Injectable Nano-Organogels (TINO’s). The TINO’s were analysed for its swelling and erosive properties. Results showed that the TINO’s posesses both swelling and erosive properties. Furthermore, the TINO’s underwent dissolution studies that involved thermal and thermal with ultrasound stimuli to test the drug release rate and the stimuli responsiveness of the TINO. Results of the SLN’s showed a very slow release rate whether exposed to a single (thermal) or both thermal and ultrasound stimuli, indicating that the addition of ultrasound stimuli did not alter the drug release from the SLN’s. However, the incorporation of the SLN’s into the TIO’s prolonged the release rate. Hence increasing the SLN concentration in the TIO’s reduced the response towards ultrasound stimuli. Therefore lower ratios of SLN:TIO provided superior responsiveness compared to higher concentrations of SLN:TIO. TIO 1 and TINO 2 released drug with thermal stimuli and higher drug release occurred with exposure to both thermal and ultrasound stimuli. These TINO’s in conjunction with ultrasound responsiveness may be used as a potential platform for the delivery of antineoplastics in treating cervical cancer.
A dissertation submitted to the Faculty of Health Sciences, University of the Witwatersrand, in fulfilment of the requirements for the degree of Master of Pharmacy