ENHANCED ETOPOSIDE SOLUBILITY AND ANTICANCER ACTIVITY USING COMPLEXATION AND NANOTECHNOLOGY

Abstract

Etoposide is a first line treatment for different cancer types that can be used either alone or in combination with other therapeutic agents. However, systemic toxicity, variable oral bioavailability, and high drug resistance are the three main drawbacks which hamper etoposide activity. The central hypothesis of this work is to enhance etoposide (VP-16) solubility, dissolution, and improve its antitumor activity using emerging formulations strategies such as complexation and nanotechnology. To test this hypothesis, three different formulations have been prepared with three specific aims: (i) co-amorphous salt formation with drug complexation by L-Arginine (ARG), (ii) solid dispersion of V-P16 (C-VP-16) in Sodium Acetate (SA) crystal, and (iii) nanomicellar formulation (NMF) using D -α-Tocopherol polyethylene glycol 1000 succinate (Vitamin E TPGS ) and solvent evaporation thin-film rehydration technique. All resulting formulations are thoroughly physico-chemically characterized with FT-IR/ 1H-NMR spectroscopies, powder X-Ray Diffraction, and Scanning electron microscopy (SEM). Liquid chromatography-mass spectrometry, and cell viability assay on MCF-7 cell line are performed to assess the drug chemical stability, cellular uptake and antitumor activities, respectively. iv In the first formulation, at the VP-16: ARG ratio of 4:10 w/w, the drug apparent solubility increased dramatically (∼49-fold) with a 3.5-fold improvement in the drug dissolution rate. The interaction between VP-16 and ARG transforms the drug from crystalline to amorphous solid state. The VP-16: ARG complex in lower native drug concentration range (50-300 µM), has lower antitumor activity than that of native VP-16, due to reduced intracellular transport of the more hydrophilic complex. However, at higher drug concentrations (500 µM) the complex’s higher antitumor activity is ascribed to increased drug transport and synergistic effect between ARG and VP-16. These data suggest that an optimal ARG concentration can have positive effects with potential benefits for chemotherapy. In the second formulation, the C-VP-16 in 1:14 w/w ratio shows a 4-fold increase in the drug dissolution rate, compared to the native VP-16 whereas it decreases to 2.5 fold in 1: 4 w/w ratio. The MTS assays results revealed that C-VP-16 cell cytotoxicity is comparable to the native VP-16. Overall, the study demonstrates that sodium acetate enhanced the dissolution kinetics of a BSC class 4 drug. In the third formulation, the MTS cell viability assay results showed that the VP-16 NMF platform provides a higher antitumor activity than that of the native VP-16 on the MCF7 cells line as it exhibits a dual antitumor activity from the drug (VP-16) and the adjuvant (TPGS). LC/MS data show a 3 fold increase in cellular uptake of VP-16 NMF in MCF-7 cells line compared to the native etoposide. These data suggest that an optimal TPGS concentration can improve VP-16 bioavailability and efficacy with potential benefits for chemotherapy.