Ethylcellulose-Based Matrix-Type Microspheres: Influence of Plasticizer RATIO as Pore-Forming Agent

Abstract

Abstract. In this study, ethylcellulose (EC)-based microsphere formulations were prepared without and with triethyl citrate (TEC) content of 10% and 30% by water-in-oil emulsion-solvent evaporation technique. Diltiazem hydrochloride (DH) was chosen as a hydrophilic model drug and used at different drug/polymer ratios in the microspheres. The aim of the work was to evaluate the influence of plasticizer ratio on the drug release rate and physicochemical characteristics of EC-based matrix-type microspheres. The resulting microspheres were evaluated for encapsulation efficiency, particle size and size distribution, surface morphology, total pore volume, thermal characteristics, drug release rates, and release mechanism. Results indicated that the physicochemical properties of microspheres were strongly affected by the drug/polymer ratio investigated and the concentration of TEC used in the production technique. The surface morphology and pore volume of microspheres significantly varied based on the plasticizer content in the formulation. DH release rate from EC-based matrix-type microspheres can be controlled by varying the DH to polymer and plasticizer ratios. Glass transition temperature values tended to decrease in conjunction with increasing amounts of TEC. Consequently, the various characteristics of the EC microspheres could be modified based on the plasticized ratio of TEC.

Improved Stability of Rifampicin in the Presence of Gastric-Resistant Isoniazid Microspheres in Acidic Media

“…These results were similar to those reported where formulations coated with lower molecular weight EC exhibited faster release rates and extent of API release when compared to formulations coated with higher molecular weight EC [64]. The expected mode of RIF release would be diffusion control and the channels for diffusion would have been created by the dissolution of d-glucose and the number of the channels was expected to increase with an increase in the amount of d-glucose included [60,61]. Eudragit ® RLPO was expected to undergo time-dependent erosion and its effect on RIF release may have been a result of the restricted entry of dissolution medium by EC into the microspheres [41] or initial swelling in aqueous media [66] that may impede RIF diffusion.…”

“…As RIF is hydrophobic, release from the microspheres would be dependent on the availability of pores and/or erosion or dissolution of the dosage form [59]. The dissolution of d-glucose is expected to create pores in the surface(s) of the microsphere coating, facilitating the entry of dissolution medium into the microspheres and outward diffusion of RIF from the core of the particle and similar results have been reported [60,61]. It was expected that increasing the amount of d-glucose would result in a greater number of pores forming on the surface(s) of the microspheres with a subsequent increase in the % RIF released due to channel formation, through which diffusion could occur, as has been reported [62,63].…”

Effect of the formulation parameters on the encapsulation efficiency and release behavior of p-aminobenzoic acid-loaded ethylcellulose microspheres

“…The T g was difficult to detect, it generally depends on the molecular weight and the degree of substitution of the used EC. It was registered by other authors [30][31][32] that the variability of the thermal transition temperature T g depends on the structure of the EC and the addition of certain compounds, such as plasticizer, introduced to increase the porosity of the microspheres. 32 The elongation, flexibility and T g decreased significantly with increasing number of ethoxy groups in the EC.…”

Development and in-vitro evaluation of chitosan chloride decorated PLGA based polymeric nanoparticles of nimesulide

“…To evaluate production yield which is one of the important parameters in nanoparticle characterization, nanoparticles were weighed to get the solid nanoparticle amount, and this value and the solid material amount were used to calculate the production yield in percentage (25,26) (Eq.1).…”