Preparation and evaluation of various formulation effects of the second emulsion on the shape and release profile of propranolol HCl from ethyl cellulose microparticle blends

Abstract The objective of this study was to investigate and characterize incorporated propranolol HCl (Pro) within ethyl cellulose microparticle blends using the solvent evaporation method. The microparticle blends were prepared with a water‐in‐oil‐in‐water (W/O/W) solvent evaporation method and contained the same drug Propranolol HCl (Pro). The first Pro emulsion (W/O) and second Pro emulsion (W/O) were dispersed in an external aqueous phase, with a dispersion time interval (DTI) of 0 and 60 min. The morphology of the microparticle blends was characterized by SEM. The mean particle size, chord length distribution and chord count of the emulsion droplets/hardened microparticles were monitored by focused beam reflectance measurement (FBRM). The encapsulation efficiency and in vitro drug release in phosphate buffer (pH 7.4) were also investigated. The resulting microparticles were spherical, of two populations. The mean particle size of the microparticle blends ranged from 104.26 μm to 127.64 μm. The encapsulation efficiency was about 76.53% to 78.81% for propranolol HCl in the microparticle blends. FBRM studies showed that the size of the microparticle blends prepared by the W/O/W (Pro) method with DTI 60 min and stirring time 4 h was larger than that of the microparticle blends with DTI 0 min. In vitro drug release studies after 28 days showed that the propranolol HCl release from microparticle blends with DTI 60 min (54.05%) was slower than from microparticle blends with DTI 0 min (73.28%). Based on these data, there is an interaction of the second primary emulsion with hard particles from the first primary emulsion, whereby the second primary emulsion blocked and coated pores on the surface of hard particles from the first primary emulsion. These blocking and coating effects of the microparticles depended on the method and the DTI. In conclusion, novel microparticle blends containing drugs of the same solubility offer high potential for controlled release drug delivery systems. © 2022 The Authors. Polymer International published by John Wiley & Sons Ltd on behalf of Society of Industrial Chemistry.