Ysr. Krishnaiah et al., Studies of guar gum compression-coated 5-aminosalicylic acid tablets for colon-specific drug delivery, DRUG DEV IN, 25(5), 1999, pp. 651-657
The aim of this study was to develop colon-specific delivery systems for 5-
aminosalicylic acid (5-ASA) using guar gum as a carrier, Core tablets conta
ining 5-ASA were prepared by wet granulation with starch paste and were com
pression coated with coating formulations containing different quantities o
f guar gum (300, 200, 150, and 125 mg). In vitro drug release studies were
carried out in simulated gastric and intestinal fluids and in pH 6.8 buffer
containing rat cecal contents. The application of 175 mg of coating formul
ation containing 150 mg of guar gum over 5-ASA core tablets resulted in the
release of less than 2% drug in simulated gastric and intestinal fluids an
d about 93% of 5-ASA in pH 6.8 buffer containing mt cecal contents, Differe
ntial scanning calorimetric (DSC) studies showed the absence of any interac
tion between 5-ASA and the excipients on storage at 45 degrees C for 12 wee
ks. The study confirmed that selective delivery of 5-ASA to the colon can h
e achieved using guar gum as a carrier in the form of a compression coating
over the drug core.