Preformulation and preliminary formulation studies of mesalazine gastro-resistant tablets

Mesalamine, 5-aminosalicylic acid or mesalazine is the standard therapy of inflammatory bowel disease. A small number of pharmaceutical dosage forms with mesalazine are on the market. The aim of this study was preformulation and preliminary formulation studies of oral gastro-resistant tablets containing 500 mg mesalazine. The reasons why a gastro-resistant tablet was chosen are: increased compliance of the patient, increased chemical stability and modified release modulation (mesalazine has a local effect on mucosa). The raw materials were of pharmaceutical grade. The following analytical techniques were involved: differential scanning chromatography (DCS), in vitro release, particle size determination, high performance liquid chromatography (HPLC). The compatibility of mesalazine with several excipients was tested using DSC. Wet granulation of mesalazine and starch showed that the fourth (LM04) formulation generates the highest amount (69.1%) of granules in the range of 1000–300 μm. Oblong tablets (pilot batches) were produced. The cores were coated with an enteric coating acrylic agent in order to achieve gastro-resistance. A new gastro-resistant tablets mesalazine formulation was developed by means of wet granulation, tableting (oblong tablets) and coating.