Propranolol HCl release profiles from ethyl cellulose based microparticle blends

The purpose of this study was to investigate effect of dispersion time interval (DTI) and formulation of second primary emulsion on ethyl cellulose based microparticle blends contained the same drug (propranolol HCl [Pro]). Microparticle blends were formulated with W/O/W solvent evaporation method. The first Pro emulsion (W/O) and second Pro emulsion (W/O) were dispersed in an external aqueous phase, with DTI of 0 and 60 min. The morphology of microparticle blends were characterized by optical microscopy and scanning electron microscopy (SEM). The particle size mean of the emulsion droplets/hardened microparticles were monitored by focused beam reflectance measurement (FBRM). Encapsulation efficiency (EE) and in vitro drug release in phosphate buffer (pH 7.4) were also investigated. Results showed the resulting microparticle blends obtained by solvent evaporation method were spherical and two populations. FBRM data showed the size of microparticle blends prepared with DTI of 60 min and stirring time 4 h was larger than the microparticle blends with DTI of 0 min. The encapsulation efficiency (EE) was about 76.53% to 78.81% for propranolol HCl in microparticle blends containing the same drug. In vitro drug release in phosphate buffer (pH 7.4) after 28 days showed the propranolol HCl release from microparticle blends contained the same drug with DTI 60 min (54.05%) was slower than microparticle blends with DTI 0 min (73.28%). This phenomenon attributable to the interaction of second primary emulsion (Pro) with hard particles from first primary emulsion (Pro), whereby the second primary emulsion (Pro) had blocked and coated pores on the surface of hard particle from first primary emulsion. The novel microparticle blends containing drugs of the same solubility offer a high potential for controlled release drug delivery systems. Key words: microparticles blend, propranolol HCl, ethylcellulose, FBRM, solvent evaporation method