Acrylic polymers derived from high solid emulsions as excipients to pharmaceutical applications: synthesis and characterization
Novel polymeric excipients need to be designed to allow for the controlled delivery of many drugs to treat a variety of diseases. In this work, two polymers based on different proportions of ethyl acrylate, methyl methacrylate, and butyl methacrylate were synthesized by multistage emulsion polymerization using a redox initiator system to yield excipients for the manufacture of prolonged release tablets by the coating or compression technique. Fourier Transform Infrared spectrometer (FTIR) indicated that the polymerization reaction of the monomers was complete without carbon double bond absorption bands. Differential Scanning Calorimetry (DSC) analysis indicated that the glass transition temperature (T
 g) of the polymers was around 50 °C. The dispersions obtained were characterized in terms of particle size and particle size distribution (PSD) using Dynamic Light Scattering (DLS), and the particle charge (zeta potential) was measured by electrophoretic mobility. The measurements showed particle diameters of approximately 200 nm and a zeta potential close to −60 mV. The low viscosity obtained for the polymers was attributed to bimodal PSD. The dispersions were freeze dried and the particles were submitted to in vitro cell tests to make a preliminary check of the toxicity of the materials. The low viscosity of the polymers, the absence of volatile solvents, and the high solid content (>50%) are ideal for these polymers to be used as coatings and matrices pharmaceutical excipients for prolonged release tablets. In vitro MTT tests suggested that the materials can be considered nontoxic.