Preparation of tetracycline-containing acrylic polymer microparticles by an in-liquid drying process from an oil-in-oil system

This paper describes the production and characterization of polyacrylic polymer microparticles by using an oil-in-oil system. Microparticles were designed for oral administration of tetracycline. Eudragit L 100, Eudragit S 100 and Eudragit RS 100 microparticles were produced by an oil-in-oil-based in-liquid drying process using as external phase light mineral oil. Microparticle morphology was characterized by optical and electron microscopy. The release kinetics of the antibiotic from microspheres were determined by using two different experimental approaches, a flow-through cell method and a dialysis method. The oil-in-oil method here described allows the production of microparticles with a high encapsulation efficiency and appropriate dimensional and morphological characteristics for oral administration. Release profile data indicate that tetracycline is released from microparticles with a rate adequate for a sustained enteric delivery. In addition the release pattern of the drug is ...