Hybrid materials based on montmorillonite and citostatic drugs: Preparation and characterization

The purpose of the present study is the preparation and characterization of montmorillonite/antitumor drug hybrids which can be further included in drug delivery systems (DDS) for oral chemotherapy. Materials used for obtaining montmorillonite-based complexes were sodium montmorillonite (MMT, ClNa) as the clay mineral phase and three pharmacologically active substances: one of them being hydrophobic (aminoglutethimide), the others, hydrophilic (irinotecan and carboplatin). For each of the three pharmaceuticals, the MMT/drug complex was prepared by mixing a MMT/water stable suspension with the drug solution; the resulting MMT–drug hybrid was analyzed before and after washing it with water. The experimental techniques used for characterizing the clay mineral and the hybrid materials obtained by drug intercalation into the MMT structure were: X-ray diffraction (XRD), infrared spectroscopy (FT-IR), complex thermal analysis (DTA, TG, DTG) and scanning electron microscopy (SEM). Adsorption of drugs in the MMT structure took place — both within the interlayer spacing, by replacing the water molecules, and on the surface. A part of the drug levigates and is lost during the washing step. Based on DTA/TG results, drug incorporation efficiency into the mineral clay decreases in the following order: aminoglutethimide, irinotecan and carboplatin.