Development of alginate esters as novel multifunctional excipients for direct compression

Methyl ester derivatives of alginic acid have been evaluated as potential multifunctional excipients for pharmaceutical direct compression. The use of alginic acid as an excipient in tablet formulation is limited because of certain drawbacks such as low tablet hardness and poor compressibility. The objective of this work is to improve these properties through esterification of alginic acid, chemical modification commonly used for enhancing the functionality of tableting excipients. It has been observed that the degree of methylation (DM) has a profitable impact in the physico-chemical and mechanical properties of the obtained materials. In general, an increase in the degree of methylation yielded tablets with higher tensile strength and better compressibility. Furthermore, modified alginates exhibited extended disintegration times compared to native alginic acid due to the introduced hydrophobicity. Finally, the functional versatility of the modified alginates as disintegrating and filling/binding agents was tested by formulating them with microcrystalline cellulose and lactose.