Eudragit S100 coated microsponges for Colon targeting of prednisolone

Microsponge is a novel approach for targeting the drug to the colon for the management of colon ailments such as inflammatory bowel disease.

Prednisolone loaded microsponges (PLMs) were prepared and coated with Eudragit S 100 (ES) and evaluated for colon-specific drug delivery.

PLMs were prepared using quasi emulsion solvent diffusion technique using ethyl cellulose, triethylcitrate (1% v/v, plasticizer) and polyvinyl alcohol (Mol. Wt. 72 kDa, emulsifying agent). The developed microsponges were compressed into tablets via direct compression technique using sodium carboxymethyl cellulose (Na CMC) and magnesium stearate as super-disintegrant and lubricant, respectively. The tablets were then coated with ES to provide protection against harsh gastric environment and manifest colon-specific drug release.

PLMs were found to be nano-porous spherical microstructures with size around 35 µm and 86% drug encapsulation efficiency. Finally, they were compressed into tablets which were coated with Eudragit S 100 In vitro drug release from ES coated tablets was carried out at various simulated gastrointestinal fluids i.e. 1 hr in SGF (pH 1.2), 2 to 3 h in SIF (pH 4.6), 4-5 h in SIF (pH 6.8), and 6-24 h in SCF (pH 7.4) and the results showed the biphasic release pattern indicating prolonged release for about 24 h.

In vitro drug release studies revealed that drug starts releasing after 5 h by the time PLMs may enter into the proximal colon. Hence maximum amount of drug could be released in the colon that may result in reduction in dose and dose frequency as well as side effects of drug as observed with the conventional dosage form of prednisolone.