Preparation and characterization of к-carrageenan and xyloglucan blends for sustained release of a hydrophilic drug

Abstract

Tamarind seed xyloglucan (TSX) and к-carrageenan (KC) have been widely used in the food and pharmaceutical industries. Their synergistic effects and the gelation and degelation of the blends, and the release a hydrophilic model drug, nicotinamide, from the blends were investigated. The KC/TSX blend with a ratio of 1 % (w/v) of KC to 1 % (w/v) of TSX (1KC/1TSX) exhibited the highest synergistic effect. The sol–gel and gel–sol transition temperatures of the blends shifted to higher temperatures when compared with KC alone. The interactions between KC and TSX in the gel state were revealed by ATR-FTIR showing the significant differences in the position and intensity of the peaks at 1164, 1124 and 1130 cm−1 for the 1KC/1TSX gel sample. These were probably due to the intermolecular hydrogen bonds between the OH and C–O–C groups of KC and TSX. In addition, the sol and gel states of the KC or KC/TSX blends could be differentiated using ATR-FTIR. Furthermore, the time needed to release 90 % (T 90) of nicotinamide alone and nicotinamide from 2KC, 1.5KC/0.5TSX, 1KC/1TSX and 0.5KC/1.5TSX was 17, 66, 75, 95 and 78 min, respectively. This demonstrated a sustained release of the drug when incorporated into the KC or KC/TSX blends in the freeze-dried samples. Moreover, the blends retarded the release better than KC alone. The blend of 1KC/1TSX, that exhibited the highest synergism, provided the most effective retardation of the compounds.