Objective. The purpose of the recent study was to prepare and estimate sustained release of Ethylcellulose (300？cps) and Eudragit (RS 100 and RL 100) microparticles containing Propranolol hydrochloride used as a treatment of cardiovascular system, especially hypertension. Method. Propranolol hydrochloride was microencapsulated with different polymers (Ethylcellulose, Eudragit RS, and Eudragit RL) using modified hydrophobic (O/O) solvent evaporation method using 1？:？1 combination of acetone and isopropanol as the internal phase. Obtained microparticles were showing higher batch yield with higher encapsulation efficiency. Microparticles were prepared with different ratios of 1？:？1, 1？:？3, 1？:？5, and 1？:？7 (%, wt/wt) using span 80 (%, v/v) as a surfactant. Results. The influence of formulation factors like drug: polymer ratio, internal phase, and type of polymers on obtained microparticles was characterized with respect to particle size distribution, encapsulation efficiency, percentage yield, FTIR, and FE-SEM. Higher encapsulation efficiencies were obtained with various polymers like Ethylcellulose (96.63？±？0.5) compared to Eudragit RS 100 (83.70？±？0.6) and RL 100 (89.62？±？0.6). The in vitro release study was characterized by initial burst. Conclusion. The result of study displays that Ethylcellulose and Eudragit loaded microparticles of Propranolol hydrochloride can be effectively prepared using modified hydrophobic emulsification solvent evaporation technique. Therefore, the modified hydrophobic emulsion technique can also be applied to the preparation of microparticles for low molecular weight and highly water soluble drugs. 1. Introduction Ethylcellulose, a nonbiodegradable and biocompatible polymer, one of the extensively studied encapsulating materials for the controlled release of pharmaceuticals, was selected as the retardant material for Propranolol hydrochloride. Ethylcellulose, a polymer to microencapsulate a drug by coacervation phase separation technique, emulsion solvent evaporation technique, and spherical crystallization technique [1]. Eudragit RS and Eudragit RL are biocompatible copolymers synthesized from acrylic and methacrylic acid ester having similar structure that differs only in the extent of the quaternary ammonium substitution and hence high water permeability and hydrophilicity in Eudragit RL as compared to Eudragit RS polymer [2]. Propranolol hydrochloride exhibits short biological half-life (2-3). It is a beta blocker and commonly used for the treatment of hypertension which affects nearly about 10–20% of the population [3,
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