The aim of this study was to develop and evaluate a multiparticulate modified release system, composed of minitablets with a sustained release matrix system coated with a pH-dependent release polymer, using mesalamine as a model drug. Polyox ® WSR 1105 was the polymer used in the matrix system and Eudragit ® L30D55 was used as a pH-dependent polymer. The minitablets (with 20%, 30% or 40% Polyox ® concentration) were prepared by dry granulation, which led to good quality minitablets. The developed minitablets were coated in a fluidized bed at 8% of the coating level. Dissolution studies were performed in media that simulated the gastrointestinal tract (pH 1.4, 6.0 and 7.2) and showed that formulations with higher Polyox ® concentrations were capable of retaining the drug release in pH 1.4. All formulations prolonged the drug release and presented zero-order kinetic behaviour. The Korsmeyer-Peppas model demonstrated that formulations with 20% or 30% of polymer exhibited anomalous transport behaviour, whilst the 40% sample exhibited super case II model transportation. Dissolution efficiency showed that only the formulations containing 20% and 40% polymer could be considered statistically different.Uniterms: Mesalamine/modified release/evaluation. Minitablets coated/modified release/evaluation. Polyethylene oxide/drugs coating. Drugs/modified release.O presente trabalho teve como objetivo desenvolver e avaliar um sistema multiparticulado de liberação modificada, composto por minicomprimidos com sistema matricial de liberação prolongada revestidos com polímero de liberação pH-dependente, utilizando mesalazina como fármaco modelo.
INTRODUCTIONSolid dosage forms are the most frequently used for oral administration, and tablets represent the most common pharmaceutical form used (Allen, Popovich, Ansel, 2005). Oral dosage forms can be classified into two broad groups: single unit dosage forms, as capsules and tablets, and multiple unit dosage forms, such as granules, pellets and minitablets (Lopes et al., 2006).Multiparticulate dosage forms present multiple advantages over single unit dosage forms, demonstrated as flexibility during formulation development and D. F. Souza, K. Goebel, I. F. Andreazza 530 therapeutic benefits for the patients, including increased bioavailability, reduced risk of systemic toxicity due to dose dumping and reduced risk of local irritation, besides predictable gastric emptying (Kramar, Turk, Vrecer, 2003).Although the oral dosage form is the most widely accepted route of administration, the gastrointestinal tract presents several barriers to drug delivery (Gupta, Beckert, Price, 2001). In this way, pharmaceutical technology has played a fundamental role in the investigation of systems that efficiently deliver a drug to its site of action (Déo, Andreazza, Possamai, 2011). The use of modified release allows a drug to be delivered at a rate dictated by the needs of the body over the period of treatment (extended release) and also avoids or directs the drug to specific sites, as in delayed relea...