Etodolac (ED), 1,8-diethyl-1,3,4,9-tetrahydropyrano-[3,4-b]indole-1-acetic acid, is a nonsteroidal anti-inflamatory and antirheumatic drug. A biocompatible and biodegradable polymer dextran was used as a carrier in the study for synthesizing macromolecular etodolac prodrugs. The synthesis involves condensation of acyl imidazole derivatives of etodolac with dextran of different molecular weights (10000 and 20000) to obtain etodolac-dextran prodrugs ED10 and ED20 respectively. The structures were confirmed by IR and NMR spectroscopy and the degree of substitution was obtained as 13.3 % and 16 % for ED10 and ED20 respectively. Hydrolysis kinetics of the synthesized prodrugs were studied in borate buffer solutions (pH 7.4 and pH 9.0) and simulated colonic fluid (SCF, pH 6.8). Much faster hydrolysis was observed in SCF than borate buffer solutions and the hydrolysis followed first order kinetics. The pharmacological evaluation showed an enhanced anti-inflammatory activity of 61 % and 65 % inhibition of ED10 and ED20 against 52 % of parent drug. The analgesic activity of the prodrugs was insignificant, whereas a remarkable reduction in ulcerogenicity was observed. The improved aqueous solubility, increased therapeutic efficiency and reduced gastrointestinal side effects of the prodrugs confirm the use of dextran as a promoiety for the delivery of etodolac in colon.
