Sustained release of salicylic acid from ethyl cellulose microspheres fabricated using quasi-emulsion solvent diffusion method

Abstract

Delivery of drugs using micro-sized particles is an efficient tool. Using ethyl cellulose (EC) as a polymer and the quasi-emulsion solvent diffusion (QESD) method paves the way for the utilization of a cost-effective polymer and an efficient fabrication method. Poly(vinyl alcohol) in water was used as an external phase while EC and Salicylic acid (SA) were dissolved in dichloromethane as an internal phase. SA is known to inhibit prostaglandins and have an anti-inflammatory effect. Furthermore, it inhibits the formation of bacterial biofilm on surfaces. Microparticles of several variations were successfully fabricated using the QESD method in an efficient time frame. These microparticles ranged in size from 5 to 40 μm for these formulations. Characterization results substantiated the selection of materials used for fabrication. Cytotoxicity showed that these fabrications were biocompatible and did not inhibit cell proliferation. In vitro drug release studies showed that the fabricated EC microparticles were able to sustainably release the drugs contained within them over a 96-h time period, with most of the drug being released after 48 h. This release never exceeded 63% of the total drug content. PEG addition in the fabrication process of formulation ECPSA eliminated burst release, resulting in a sustained release pattern over 48 h, reaching saturation by day 5. While entrapment was dependent on the polymer content, increasing drug content did not significantly affect drug release. Behavioral studies evaluated the microspheres, revealing different kinetic models, including Higuchi in ECSA2 and Korsmeyer-Peppas in ECSA3, ECSA5, ECSA6, and ECPSA, with varying diffusion mechanisms. Future fabrications can be made to increase the porousness of the spheres to increase drug release from the microparticles. Also, drug release studies can be conducted over longer periods of time, and with near-infrared light (NIR) to observe the changes in drug release between the fabrications.