Montmorillonite as drug delivery system for gentamicin

Clays are common ingredients in pharmaceutical and cosmetic formulations as active substances (gastrointestinal protectors, osmotic oral laxatives, antidiarrhoeaics, topical antibacterials and antinflammatories) and excipients in solid forms (tablet, capsules, powder), liquid forms (suspensions, emulsions) or semisolid forms (ointments, creams). Only some clay minerals, a combination of Al or Mg octahedra and Si tetrahedra (phyllosilicates), including kaolin, talc, smectites and fibrous clays have beneficial effects in dermatological and cosmetic applications (geotherapy, palotherapy) according to their rheological and thermal properties as well as cation exchange capacity (CEC) and absorption. More, the intercalation of several drugs or cosmetic substances in smectites could represent an advantageous approach to design delivery systems for the topical use. Clay-drug interaction affects the properties of both the dosage form (viscosity, flow property) and the intercalated drug (stability , release, absorption).Among the mineral clays, montmorillonite (MMT) has high specific surface area and it exhibits good adsorption ability, cation exchange capacity, standout adhesive ability and drug-carrying capability. As a result of clay structural and chemical characteristics, montmorillonite, a 2:1 (ratio of silica tetrahedra to aluminium and/or magnesium octahedra) layered silicate, can accomodate therapeutic compounds between the layers generating a host for oral and topical drug delivery.The present work aims to evaluate the intercalation of gentamicin molecules into MMT clay to obtain a modulating drug delivery carrier for antibiotic skin treatment. More, clay antibacterial activity could produce a synergistic effect.The intercalation process of gentamicin into the MMT interlayer at different pH value and drug concentration was examined. MMT-gentamicin hybrid was characterized by X-ray diffraction, Fourier transformed infrared, ultraviolet-visible spectroscopy, thermal analysis, differential scanning calorimetry and molecular dynamics simulation.