Development of novel topical drug delivery system containing cisplatin and imiquimod for dual therapy in cutaneous epithelial malignancy.

Strategy of dual therapy has been proposed to minimize the amount of each drug and to achieve the synergistic effect for cancer therapies. The aim of this study was to develop an effective drug delivery system for the simultaneous topical delivery of two anti-tumor agents, cisplatin and imiquimod. The preformulation studies were carried out in terms of tests for identification, solubility profile, determination of partition coefficient and simultaneous estimation of both drugs by UV-Visible spectrophotometer and High Performance Liquid Chromatography (HPLC). Drug-drug and drug-excipients interactions were examined by thin layer chromatography, infrared spectroscopy, differential scanning calorimetry (DSC) and X-ray diffraction (XRD). Provesicular drug delivery system (protransfersome gel formulation) have been prepared and characterized by in vitro and in vivo parameters. The mean size, poly dispersity index (PDI) and zeta potential of transfersomal vesicles formed by protransfersome hydration were 429.5 nm, 0.631 and -68.1 Mv, respectively. The prepared formulation showed toxicity on cutaneous squamous cell carcinoma cell line (A-431) at 200 µg (cisplatin) and 1 mg (imiquimod) concentration of drug in combination against control. The cisplatin- and imiquimod-loaded provesicular dual-drug delivery system achieved an optimal antitumor effect, increase in lifespan, antiviral, and toxicity reduction, revealing the advantage of site specific drug delivery and the modified combination therapy. Cisplatin delivery through protransfersome gel in combination with imiquimod may potentiate the activity against solid tumors of epidermal origin. Data revealed that combination therapy considerably enhances antitumor efficacy of the drug for skin-cited malignancies.